Year 11 Human Bio Glossary U - Z

Other glossary sections: (A - E) (F - J) (K - O) (P - T)

U

Ulna- One of the bones on the lower arm. It forms the point of the elbow and joins the wrist on the small finger side.
Umbilical arteries- Arteries that carry blood to the capillaries of the chorionic villi.
Umbilical cord- The structure that attaches the foetus to the placenta.
Umbilical vein- The vein that carries blood from the placenta to the foetus.
Umbilicus- The navel.
Uracil- One of the nitrogen bases present in RNA (but is not present in DNA). Pairs up with adenine.
Urethra- The tube that transports urine (as well as sperm, in the case of males) to outside the body.
Uterine arteries- Arteries that carry the mother's blood to the placenta.
Uterine tube- A tube that carries the ovum from an ovary to the uterus. Also known as the Fallopian tube or oviduct.
Uterine veins- Veins that carry the mother's blood away from the placenta.
Uterus- The womb in which the foetus develops. Held behind the urinary bladder and in front of the rectum by ligaments.

V

Vagina- The tube that leads from the uterus to the outside of the body. It is muscular and lined with mucous membranes.
Varicose veins- Enlarged and lengthened veins which cannot carry blood back to the heart efficiently, potentially resulting in the accumulation of blood in lower limbs.
Vas deferens- The sperm duct. Takes the sperm away from a testis, into the abdominal cavity, across the upper surface of the bladder and around to the back of the bladder, where it meets up with the vas deferens of the other testis and joins the urethra.
Vasectomy- A form of sterilisation. A small piece of each vas deferens is removed and the cut ends are tied. Another method includes using high frequency ultrasound to kill the cells in the wall of the vas deferens, causing dead cells to coagulate and form an obstruction in the tube.
Veins- Relatively large blood vessels that take blood back to the heart. They have relatively thin walls as they carry low-pressure blood. They contain valves that prevent backflow of blood. The veins are squeezed, pushing blood along, when surrounding muscles contract.
Ventilation- A fancy word for "breathing."
Ventricle- The chamber of the heart that blood passes through after passing through the atrium. It has thick muscular walls, particularly on the left side of the heart, in order to pump blood around the lungs and body.
Ventricular systole- A stage of the cardiac cycle that lasts roughly 0.3 seconds. During this stage, blood is forced into the arteries from the ventricles.
Venules- Small veins.
Vernix- The protective waxy layer that covers newborn babies.
Vertebrae (singular: vertebra)- The bones making up the vertebral column. The top seven are the cervical vertebrae, the next twelve are the thoracic vertebrae, the next five are the lumbar vertebrae, and then the sacrum and coccyx are located at the bottom.
Vertebral column- The backbone.
Vertebrata- A subphylum that includes animals with backbones.
Villus (plural: villi)- A bristle-like projection, about 1mm long, that has smaller projections called microvilli. Inside each villus are blood capillaries and lacteals (a type of lymph capillary). Villi only have one layer of cells on their surfaces, allowing for easy diffusion of substances.
Vital capacity- The maximum amount of air that can be exhaled after inhaling as much air as possible.
Vitamins- Molecules that are essential for regulating cellular reactions and allowing cells to gain energy from proteins, carbohydrates and fatty acids. They cannot be manufactured in the body, but a balanced diet should give you all of the vitamins that you need.
Vocal cords- The edges of the vocal folds. They have elastic ligaments that can vibrate.
Vocal folds- The mucous membranes stretched between the pieces of cartilage making up the larynx.
Vulva- The region surrounding the opening of the vagina and urethra (in females).

W

Weaning- Moving onto solid foods.
Whiplash- The head flings back and forth during a sharp impact, causing ligaments to tear and internal bleeding to occur. Nerves may also be injured. There are many symptoms of whiplash, including headaches, dizziness, nausea, pain and weakness. If the injury is such that the axis is driven into the brain stem, death may occur.
White blood cells- Blood cells that defend the body against invading microorganisms and remove dead or injured cells. They are (obviously) white.

X

Y

Yellow bone marrow cavity- A fat storage site within bones.
Yolk sac- One of the embryonic membranes. Forms red blood cells and will become part of the umbilical cord.

Z

Zygote- The single diploid cell formed from the fertilisation of a sperm and ovum.
Zygote intrafallopian transfer (ZIFT)- A form of ART where the eggs are fertilised in the lab. At the zygote stage, normally a day after fertilisation, the zygote is transferred to the woman's uterine tubes.

Year 11 Human Bio Glossary P - T

Other glossary sections: (A - E) (F - J) (K - O) (U - Z)

P

Palliation- Treatment focused on reducing the symptoms (if there is no cure available).
Pancreas- An organ located just beneath the stomach, in the curve of the duodenum. It secretes pancreatic juice, which contains enzymes that aid in digestion, as well as the hormones insulin and glucagon, which regulate sugar levels in the blood.
Pancreatic amylase- A digestive enzyme in the pancreatic juice that breaks down starch into disaccharides, particularly maltose.
Pancreatic duct- A duct in the pancreas that the pancreatic juice travels through. Joins up to the common bile duct, which then enters the duodenum.
Pancreatic juice- A liquid secreted by the pancreas that contains digestive enzymes including pancreatic amylase, trypsin (a.k.a. pancreatic protease), ribonuclease, deoxyribonuclease and pancreatic lipases. It is slightly basic, thus neutralising any HCl that might still be in the chyme (the mixture formed after digestion in the stomach).
Pancreatic lipase- A digestive enzyme in the pancreatic juice that breaks down fats into fatty acids and glycerol.
Pancreatic protease- A digestive enzyme in the pancreatic juice that breaks down proteins into smaller peptide chains. Also known as trypsin.
Paraplegia- Paralysis of both of the lower limbs.
Parent cell- A term used to refer to the original cell (after cell division has occurred).
Parturition- Birth of a newborn baby.
Patella- A triangular bone also known as the "kneecap."
Pectoral girdle- The shoulder girdle. Consists of the clavicle and scapula.
Pelvic bones- The two main bones of the pelvic girdle. Also known as the hip bones.
Pelvic girdle- The hip girdle or pelvis. Consists of the pelvic bones.
Pelvic inflammatory disease (PID)- An infection of the pelvic organs of the female reproductive tract.
Pentadactyl- Animals that have five mobile digits on each limb.
Pepsin- An enzyme that breaks proteins and other long chains of amino acids down into shorter chains, or polypeptides. Also known as gastric protease.
Pepsinogen- An inactive form of pepsin. Pepsin is secreted in this form so that digestion does not occur in the lining of the stomach. Pepsinogen is inactive in alkaline surroundings and requires contact with HCl to activate.
Peptidase- An enzyme in the intestinal juice that breaks down peptide chains.
Peptide bond- The bond between two amino acids.
Pericardium- A membrane that surrounds the entire heart in order to hold it in place and prevent it from over-beating while still giving it some freedom to move while beating.
Periosteum- A dense, white fibrous covering on the outer surface of bones.
Peripheral vascular diseases- Cardiovascular diseases affecting the limbs. Includes phlebitis, varicose veins and arteriosclerosis in the limb arteries.
Peristalsis- Muscle movements in the alimentary canal that push the food along.
Pernicious anaemia- Anaemia caused by inadequate B12.
Phagocytosis- A process in which a cell surrounds and engulfs bacteria, dead cells, fragments and so on. If the substance is liquid, the process is called pinocytosis instead.
Phalanges- Bones in the fingers and toes.
Pharyngeal pouches- The "gill slits" present in the early embryonic stage.
Pharynx- A cavity in the back of the mouth. It is roughly 13 centimetres long and extends from the nasal cavity downwards.
Phenylketonuria (PKU)- A genetic disorder that can result in severe mental retardation. The gene controlling the production of an enzyme that breaks phenylalanine down is affected, so toxic levels accumulate in the blood, resulting in damage to the growing brain.
Phlebitis- Inflammation of a vein. May cause blood clots.
Phospholipid- A lipid that is a part of cell membranes.
Pinocytosis- A form of endocytosis in which the substances taken into the cell are liquid.
Pituitary gland- An endocrine gland located below the brain and above the mouth. Secretes a variety of hormones, including the gonadotropic hormones.
Pivot joint- Joint in which one bone has a circular, pointed or conical end, which rotates upon the axis of another bone. A prime example of this is the joint between the first vertebra (on which the head is balanced) and the second vertebra.
Placenta- A structure that supplies the foetus with nutrients while removing its wastes. Other functions include producing oestrogen and progesterone. Fully formed by the end of the third month of pregnancy.
Plasma- One of the components of the blood, comprising of 55% of the blood. Plasma is 91% water and 7% plasma proteins and also contains ions and some other substances such as dissolved nutrients and gases, hormones and waste products from cells.
Plasma membrane- A structure that separates the cell from neighbouring cells and the external environment. It is made up of a double layer of lipid molecules as well as various proteins associated with the lipids. Allows some substances to get through but not others. Also known as the cell membrane.
Plasma proteins- Proteins in the plasma.
Platelet- A type of blood cell that forms blood clots when blood vessels are damaged. Also known as a thrombocyte.
Pleura- The two-layered membrane surrounding the lungs. The outer layer adheres to the inner wall of the chest cavity, while the inner layer covers the inner surface of the lungs. Also known as the pleural membrane.
Pleural cavity- The space between the two layers of the pleural membrane.
Pleural fluid- The fluid inside the pleural cavity. Provides lubrication, allowing the two layers to slide against each other. Also holds the lungs in place.
Pleural membrane- The two-layered membrane surrounding the lungs. The outer layer adheres to the inner wall of the chest cavity, while the inner layer covers the inner surface of the lungs. Also known as the pleura.
Pneumonia- An infection caused by some bacteria, viruses or fungi, most notably the pneumococcus bacterium. The inflammation causes fluid to accumulate in the alveoli.
Polypeptide- Ten or more amino acids joined together.
Polysaccharide- Long chains of simple sugars (monosaccharides). One example is glycogen, the form in which carbohydrates are stored in the body.
Polyunsaturated fat- A fat in which there are multiple double bonds between C atoms.
Postural reflexes- Movements involved in adjusting stance so as to maintain balance. Occur without conscious thought.
Power grip- The grip involved in holding objects.
Precision grip- The grip involved in fine movements such as writing or se
Prehensile- Capable of grasping.
Preimplantation genetic diagnosis (PGD)- A technique that can be used to test embryos for genetic defects. Banned in some places due to ethical issues.
Pre-menstrual syndrome (PMS)- A range of symptoms that some women experience prior to menstruation. Symptoms are varied, ranging from mood swings to bloating to joint pain, and so on.
Premolars- Teeth used for crushing and grinding (along with the molars).
Primary amenorrhoea- A menstrual abnormality in which menstruation does not begin during adolescence.
Primary bronchi- The pair of bronchi that enter the lungs. These then divide into secondary bronchi, which divide into tertiary bronchi etc.
Primary follicle- An ovum surrounded by a single layer of cells.
Primary germ layers- The ectoderm, mesoderm and endoderm. Formed by the cells of the inner cell mass. Will develop into all of the tissues and organs of the body.
Primary oocyte- A grown oogonium. Surrounded by a single layer of cells, forming a primary follicle.
Primary spermatocytes- Diploid cells formed when spermatogonia are pushed into the centre of the seminiferous tubules.
Primates- An order (taxonomic rank) within the Mammalia class that consists of animals with forward-facing eyes and nails instead of claws.
Prime mover- The muscle in the pair that carries out the desired action. Opposite to this is the antagonist. The prime mover is also known as the agonist.
Progestagen- A substitute for progesterone which is used in some types of hormonal contraception.
Progesterone- One of the sex hormones in females.
Prolactin- Hormones secreted by the pituitary gland that affect the breasts of women. Important in milk production. Also known as lactogenic hormones.
Promotion stage- The second stage of tumour development. The initiated cells start dividing and become a malignant tumour.
Prophase- The first actual stage of mitosis. The spindle forms, the nuclear membrane breaks down and the chromatin threads coil up to become chromosomes.
Prosimians- A suborder within the primates. Include lemurs, lorises, pottos and galagos.
Prostate gland- A doughnut-shaped gland that surrounds the urethra just below the bladder. Secretes a thin, milky, alkaline fluid.
Protein- A structure made up of over 100 amino acids joined together. They make up much of the structure of body cells and take part in many chemical reactions in the body. They contain the elements C, H, O and N, and sometimes S or P as well.
Protoplasm- The nucleus and cytoplasm together (i.e. all of the cell's contents).
Proximodistal pattern- A pattern involved in motor development. Parts of limbs closer to the body are able to be controlled before parts of limbs further away from the body.
Puberty- The time during which sexual maturity (physically) is attained.
Puerperium- The period of time following pregnancy, during which the organs return to their non-pregnant state.
Pulmonary artery- The artery flowing from the right side of the heart to the lungs. Splits into the left and right pulmonary arteries.
Pulmonary circulation- Circulation of blood through the lungs.
Pulmonary vein- The vein that flows from the lungs to the left side of the heart.
Pulp cavity- The inside of the tooth. Contains nerves, blood vessels and a soft tissue called pulp.
Pyloric sphincter- A thick circular muscle at the lower end of the stomach. Stops stomach contents from leaving prematurely.

Q

Quadriceps- One of the main muscle groups of the thigh. Straightens the lower leg. All quadriceps muscles have a common tendon which crosses the knee joint to join with the tibia.
Quadriplegia- Paralysis of all four limbs.
Quadrupedal- Walks on four legs.

R

Radius- One of two lower arm bones. Joins the wrist on the thumb side and forms the wrist joint.
Recovery oxygen- The extra oxygen that needs to be breathed in following a period of anaerobic respiration.
Rectum- A section at the end of the large intestine. It can contract (in conjunction with relaxation of the anal sphincter) to allow defecation to take place.
Red blood cells- Blood cells that transport oxygen to the cells. They are (obviously) red in colour.
Red bone marrow- A type of bone marrow in which many blood cells are produced.
Red cell concentrate- A transfusion containing mainly red blood cells which have been separated out. The transfusion may also contain platelets and leucocytes.
Renal arteries- Arteries that take blood to the kidneys.
Rennin- An enzyme only found in the gastric juice of infants. Makes milk proteins coagulate (become solid or semi-solid), allowing the stomach more time to break down the milk proteins.
Residual volume (of air)- The volume of air remaining in the lungs after maximum expiration.
Respiration- The process by which carbohydrates, lipids and proteins are broken down to provide energy.
Retrovirus- A virus that contains an RNA core instead of a DNA core and cannot reproduce itself.
Rheumatoid arthritis- A severe form of arthritis involving inflammation of the joint, swelling, pain and loss of function.
Rhythm method- A method of contraception. "Unsafe days" for intercourse are considered to be between days 10-17 of a 28-day cycle. This is the least reliable of the ovulation detection methods.
Ribonuclease- A digestive enzyme in the pancreatic juice that breaks down RNA.
Ribosomes- Very small, spherical organelles that can be found either floating around in the cytoplasm or attached to membranes within the cells. At the ribosomes, amino acids combine into proteins according to instructions in the DNA.
Rickets- A condition in which the bones are soft.
Right lymphatic duct- A duct of the lymphatic system.
Roots- One or two long thin bits of the tooth that extend into the sockets in the jaw bones.
Rotation- Movement in which a bone rotates around its long axis.
Roughage- Food, such as cellulose, that cannot be digested by humans, but stimulates the contraction of the muscular walls of the intestine. Also known as insoluble fibre.

S

Saddle joint- Joint in which the two bones are saddle-shaped (i.e. concave in one direction, convex in the other). This allows both side-to-side and back-and-forth movements. Pretty much only seen in the joint between the thumb and the palm of the hand.
Saliva- A substance secreted into the mouth by the salivary glands. Contains mucus to lubricate the mouth and hold the food together; a digestive enzyme called salivary amylase, which breaks carbohydrates down into shorter chains; and antibodies, which kill bacteria in the food.
Salivary amylase- A digestive enzyme that breaks down carbohydrates into smaller chains.
Salivary glands- Three pairs of glands that secrete saliva into the mouth.
Sarcolemma- The thin, transparent plasma membrane surrounding muscle cells. Contains sarcoplasm.
Sarcoma- A type of cancer that forms from supporting tissues such as cartilage, fatty tissues, bones and muscles. Around 5% of cancers are sarcomas.
Sarcomeres- Units of the myofibrils. Contain many myofilaments, which come in two varieties: thick myofilaments containing the protein myosin, and thin ones containing the protein actin.
Sarcoplasm- A kind of cell fluid present in the sarcolemma. Contains hundreds to several thousands of myofibrils.
Saturated fat- A fat in which there are no double bonds between carbon atoms.
Scapula- Shoulder blade.
Scrotum- Skin-covered pouch that holds the testes. Divided into two sacs, each containing a single testis. Contains smooth muscle fibres allowing the scrotum to move towards or away from the body, depending on the temperature.
Secondary amenorrhoea- One or more menstrual periods are missed. This is quite common and happens to nearly all women at some point.
Secondary follicle- The second stage of the development of an ovum-containing follicle. The cells surrounding the original primary follicle have grown, divided and secreted fluids, forming a fluid-filled space forcing the egg to move towards the edge of the follicle, forming a secondary follicle.
Secondary oocyte- The larger product of the first meiotic division of a primary oocyte. Does not proceed past metaphase unless the sperm meets the ovum.
Secondary sexual characteristics- Characteristics associated with a person's gender but aren't related to sexual reproduction. In females, these include breast growth and broadening of the hips. In boys, it includes an increase in the size of the larynx. In both genders, it includes the growth of body hair in various places.
Secondary spermatocytes- Haploid cells that form after the primary spermatocytes undergo meiosis.
Second-class proteins- Proteins that do not contain sufficient quantities of essential amino acids. Same as incomplete proteins.
Second polar body- The smaller product of the division of a secondary oocyte. Eventually disintegrates.
Segmentation- Movements of the muscles of the small intestine that allow food to move back and forth and mix well with the digestive juices.
Semen- A liquid that nourishes and aids the transport of sperm. Also known as the seminal fluid.
Semilunar valve- Valves at the bottom of the aorta and pulmonary artery. Consist of three cusps that hold any blood that tries to flow back, preventing backflow.
Seminal fluid- A liquid that nourishes and aids the transport of sperm. Also known as semen.
Seminal vesicles- Vesicles located behind the urinary bladder. Secrete a thick sugar-rich fluid that makes up 60% of the volume of semen.
Seminiferous tubules- Tubules located in the lobules of the testes. Lined with cells that can divide to produce sperm.
Senescence- A decline in the performance of all the organ systems.
Septum- The "wall" dividing the heart into two halves.
Seroconversion illness- An illness that may develop within two weeks of exposure to HIV. Symptoms include lack of energy, fevers, headaches, dry cough, swollen lymph nodes and pain in muscles and joints.
Serosa- The outer layer of the alimentary canal, consisting of connective tissue.
Serum- A fluid that is squeezed out during the process of clot retraction.
Sexually transmitted diseases (STDs)- Diseases that can be transmitted through exchange of bodily fluids. Also known as sexually transmitted infections (STIs).
Sickle cell anaemia- A genetic condition resulting in deformed red blood cells.
Simple epithelium- Epithelium with only a single layer of cells.
Skeletal muscles- Muscles that allow movement at the joints. Also known as striated muscles due to their appearance under a microscope, or as voluntary muscles since they can only be contracted voluntarily.
Slightly moveable joints- Joints in which bones are held together by cartilage. Slight movement can occur, but not a lot. Also known as cartilaginous joints.
Slipped disk- Part of the invertebral disc (fibrocartilage between vertebrae) is squeezed to one side, displacing the disc. Depending on how the disc has "slipped," it can put pressure on spinal nerves of the spinal cord, causing severe pain and numbness. This can then result in nerve damage, which then causes weakness and possible degeneration to the tissue of the muscles supplied by the damaged nerves.
Smooth muscles- Muscles in the internal organs. Do not have striations. Also known as involuntary muscles.
Social smiles- Actions that babies perform to respond to people, such as smiles, sounds, smiling, kicking or waving their hands.
Spasms- Short, sudden, involuntary muscle contractions.
Spermatids- Haploid cells formed after the secondary spermatocytes divide.
Spermatogenesis- The process of sperm production.
Spermatogonia- Sperm "mother cells" that are immature cells containing full sets of 46 chromosomes. These cells line the seminiferous tubules of each testis. When puberty begins, most of these cells begin to divide by mitosis, resulting in a continuous source of spermatogonia for the production of sperm.
Spermatozoa (sperm)- The male gametes. They are around 0.06mm long and are made up of a head, neck, middle piece and tail. The tip of the head contains a fluid filled vesicle which, in turn, contains enzymes which help to break down the layers surrounding the ovum. The head also contains the nuclear material. The middle piece contains mitochondria and a tiny bit of cytoplasm, while the tail's function is to propel the cell forward.
Spina bifida- A birth defect where the spine fails to join together at the back, resulting in a gap that membranes and parts of the spinal cord may push through.
Spindle- A framework of fibres formed during the prophase stage of cell division.
Spongy bone- Porous bone tissue that contains many large spaces. Also known as cancellous bone.
Sprain- A ligament is torn from the bones. Blood vessels, muscles, tendons, ligaments and nerves may also be damaged. Symptoms include swelling, pain and discolouration due to ruptured blood vessels.
Stance phase- The phase of walking during which the leg starts to support the body weight. Also known as the supporting leg phase.
Starch- A long-chain carbohydrate that is found in cereals, wheat, rice, oat, corn, bread and certain vegetables such as potatoes, peas and dried beans.
Sternum- The breastbone.
Steroid- A type of lipid. Examples include cholesterol and the sex hormones.
Strain- Symptoms include a sudden pain and loss of power in the limb. Normally occurs when a muscle or tendon is overstretched.
Stratified epithelium- Epithelium with multiple layers of cells.
Stretch receptors- Sense organs located in the joints, ligaments and tendons that give the brain input regarding balance.
Striated muscle- Another name for skeletal muscles. The name comes from the appearance of the muscles when viewed under a microscope.
Stroke- Occurs when atherosclerosis affects the cerebral arteries, causing part of the brain tissue to die. Aside from blocked arteries, cerebral haemorrhage (bleeding at a weak point in one of the arteries), can cause strokes. Strokes range in severity from mild to severe.
Stroma- The connective tissue that ovaries are composed of. Surrounded by a layer of cells containing some germ cells.
Subclavian arteries- Arteries that take blood to the arms.
Submucosa- The second innermost layer of the alimentary canal. Contains glands and connective tissue, the latter of which contains blood vessels, lymph vessels and nerves. The small intestine submucosa has many folds, increasing surface area.
Substrates- Molecules that are involved in a reaction.
Sucrase- An enzyme in the intestinal juice that breaks sucrose down into monosaccharides.
Superior vena cava- One of the main veins of the body. Takes blood from the upper body to the right side of the heart.
Supporting leg phase- The phase of walking during which the leg starts to support the body weight. Also known as the stance phase.
Swinging leg phase- The phase of walking during which the leg swings forward.
Symphysis pubis- The cartilaginous joint joining the two pelvic bones together at the front.
Symptothermal method- A method of contraception involving elements of the rhythm method, the temperature method and the mucus method.
Synapsis- A process that occurs during the prophase stage of cell division. The chromosomes pair off, each pair appearing as four strands twisted together.
Synovial fluid- Fluid secreted by the synovial membrane. Lubricates the joint, provides nourishment for the cells of the articular cartilage, and carries phagocytic cells that remove microorganisms and debris resulting from wear-and-tear. Only a small amount of fluid is usually present, but if the joint is injured or inflamed, more fluid may be produced, resulting in swelling and discomfort.
Synovial joints- Joints with a relatively large range of movement. (Movement is, however, restricted by the shape of the bones.) Also known as freely moveable joints.
Synovial membrane- The inner layer of the capsule surrounding freely moving (synovial) joints. It consists of loose connective tissue with blood capillaries. The synovial membrane lines the entire joint cavity aside from the articular cartilages and the articular discs.
Synthesis- The process of building complex molecules by combining smaller ones.
Syphilis- An STD that affects many different areas of the body throughout the course of the disease. In the first stage, small sores appear, mainly on the sex organs but also on other parts of hte body. In the second stage, there are many possible symptoms, including rashes, mild fevers, sore or ulcerated mouth or throat and disorders of the bones or eyes. In the third stage, which may occur many years later, many tissues of the body are damaged, causing a variety of severe symptoms.
Systemic circulation- Circulation of blood throughout the whole body.

T

Talus- One of the tarsals. The only ankle bone to articulate with the fibula and tibia.
Tarsals- Ankle bones. There are seven in each ankle.
Tarsiers- A suborder within the primates. Only contains tarsiers.
Taxonomic Rank- The different levels of classification in Bloom's taxonomy (the system used for classifying all living matter).
Telophase- The final step of cell division. The two sets of chromosomes group together at opposite ends of the cell, nuclear membranes form around each group, a nucleolus appears in each new nucleus, the spindle fibres disappear, and the chromosomes uncoil to become chromatin threads again. The centrioles then duplicate, ready for the next division. The cytoplasm also begins to divide during telophase: a furrow appears between the two nuclei, which gradually deepens until the cell is split in two.
Temperature method- A method of contraception based on fluctuations in temperature surrounding ovulation.
Tendinitis- Inflammation of the tendon sheaths surrounding certain joints. Symptoms include swelling and pain upon movement of the affected joint.
Tendons- Fibrous, inelastic connective tissue that attach skeletal muscles to the skeleton.
Teratogenic agent- A chemical that causes physical defects in the developing embryo. Includes alcohol, thalidomide, heroin, LSD and many medicinal drugs.
Testis (plural: testes)- Male gonads in which the sperm is produced.
Testosterone- A sex hormone in males.
Thalassaemia- A genetic form of anaemia in which there are defects in the formation of the haemoglobin molecule. People with thalassaemia need frequent blood transfusions, as well as medication to remove the excess iron in their bodies.
Thoracic cavity- The area bounded by the ribs and diaphragm. Includes the lungs, heart, aorta, venae cavae, pulmonary veins and arteries, oesophagus, thymus gland and part of the trachea and bronchi.
Thoracic duct- A duct of the lymphatic system.
Thorax- The chest.
Thrombocyte- A type of blood cell that forms blood clots when blood vessels are damaged. Also known as a platelet.
Thymine- One of the nitrogen bases present in DNA (but is not present in RNA). Pairs up with adenine.
Tibia- The larger of the two lower leg bones.
Tics- Involuntary, spasmodic twitching of muscles.
Tidal volume- The amount of air that moves in and out with every regular breath.
Tissue fluid- Fluid found between cells in the tissues. Also known as interstitial fluid or intercellular fluid.
Trabeculae- An irregular arrangement of thin, bony plates. The spaces contain bone cells, nerves and blood vessels. Found in spongy bone.
Trachea- A tube around 12cm long and 2.5cm in diameter. Air travels through here to get to the bronchi in the lungs. Contains C-shaped bands of cartilage, which allow the trachea to be flexible without collapsing. Also contain cilia, which push mucus and other solids towards the pharynx, where they can then be swallowed.
Transfer RNA- A type of RNA that brings the amino acids to the ribosomes.
Transient ischaemic attack (TIA)- A cardiovascular disease that is like a stroke but shorter and less severe.
Transverse arch- The side to side arch of the foot.
Transverse colon- The section of the colon that goes from the person's right to their left.
Trapezius- Muscle that attaches scapula to axial skeleton. Allows us to move our shoulders in various ways (e.g. shrugging).
Tricuspid valve- The atrioventricular valve on the right side of the heart, so called due to its three cusps.
Triglyceride- A fat formed from the product of glycerol and three fatty acids.
Trisomy-21- A birth defect caused by having three of the chromosome number 21. Symptoms include mental retardation and malformation of the heart, ears, hands and feet. The risk increases as the mother reaches the end of her child-bearing period. Also known as Down Syndrome.
True ribs- Ribs directly attached to the sternum by some costal cartilage.
Trypsin- A digestive enzyme in the pancreatic juice that breaks down proteins into smaller peptide chains. Also known as pancreatic protease.
Tubal embryo transfer (TET)- A form of ART in which the eggs are fertilised in the lab. The resulting zygote is allowed to divide into the 2-cell to 4-cell stage before being implanted into the woman's uterine tubes.
Tubal ligation- A form of sterilisation in which a small piece of each uterine tube is removed and the cut ends are tied.

Year 11 Human Bio Glossary K - O

Other glossary sections: (A - E) (F - J) (P - T) (U - Z)

K

Karyotype- A photograph of all of the chromosomes displayed in order.

L

Labia majora- Two fleshy folds of skin located in the vulva. Comprised of fat and fibrous tissue.
Labia minora- Two smaller folds of skin located between and beneath the labia majora. Lack fat and are pinkish in colour. Surround the openings of the urethra, vagina and the clitoris.
Lactase- An enzyme in intestinal juice that breaks lactose down into monosaccharides.
Lacteal- A lymph capillary located in the villi.
Lactogenic hormones- Hormones secreted by the pituitary gland that affect the breasts of women. Important in milk production. Also known as prolactin.
Lacunae (singular: lacuna)- Spaces between the lamellae in compact bone. Contain bone cells.
Lamellae (singular: lamella)- A bony matrix consisting of bone cells as well as non-cellular material, including inorganic salts.
Laryngitis- Swelling of the mucous membrane covering the vocal cords, making it difficult for them to vibrate.
Larynx- An organ that connects the pharynx with the trachea. Also known as the "voice box" as it has a role in producing sounds.
Leucocytes- Blood cells that defend the body against invading microorganisms and remove dead or injured cells. They are white, hence their common name, white blood cells.
Leukaemia- An abnormal number of white blood cells are produced. These white blood cells fill the red bone marrow, inhibiting the production of the red blood cells, which can lead to anaemia.
Lipase- An enzyme in intestinal juice that breaks down lipids.
Lipids- Water-insoluble molecules stored in the body as energy reserves.
Liver- A rather large organ located just below the diaphragm on the right side of the body. It has many known functions, including blood glucose regulation, deamination, fat conversion, plasma protein production, production of blood-clotting factors, storage of various substances, toxin breakdown, hormone inactivation and heat production.
Lobes- Sections of the breast. There are around 15-25 per breast. Surrounded by fatty connective tissue.
Lobules- Sub-sections of the breasts. Surrounded by fatty connective tissue. The walls are made up of lots of glandular alveoli, which secrete milk. Lead into ducts, which open up into milk spaces, which then lead into short, straight ducts to the nipple.
Longitudinal arch- The front to back arch of the foot.
Longitudinal muscle- Muscle in which the muscle fibres are arranged along the length of something else (such as the alimentary canal).
Loose connective tissue- A type of connective tissue that supports and connects other tissues. Made up of fibres and cells in a semi-fluid matrix.
Lung cancer- Involves the development of a tumour, just like other cancers. Normally begins in the walls of the bronchi- excessive production of mucus is caused by irritation of the mucous membrane lining. Trapped mucus causes alveoli to rupture, resulting in emphysema. Eventually a cancerous growth develops in a bronchus and may spread to other parts of the body.
Luteinising hormone (LH)- A gonadotropic hormone secreted by the pituitary gland. In females, LH promotes final maturation of the ovarian follicle, ovulation and the formation of the corpus luteum. Less LH is secreted as progesterone levels rise. In males, LH stimulates ccells in the testes to secrete the hormone testosterone, which is important for sperm production.
Lymph- The fluid inside the lymph capillaries. Composition is essentially the same as tissue fluid.
Lymph capillaries- Small lymph vessels that eventually join up to form lymphatic vessels.
Lymph nodes- Nodes located along the lymphatic vessels that remove bacteria and foreign particles from the lymph.
Lymphatic system- The system that drains fluid from the tissues. Consists of lymph vessels as well as the lymphoid organs.
Lymphomas- Solid tumour masses formed from cells of blood and/or lymphatic origin.
Lymph vessels- Consist of the lymph capillaries, lymphatic vessels and other ducts of the lymph system. They are squeezed when surrounding muscles contract, pushing the lymph along. They have valves to ensure that the lymph only moves in one direction.
Lymphatic vessels- Lymph vessels that eventually join up to become even bigger lymphatic vessels, which then join in to the thoracic duct and the right lymphatic duct.
Lymphoid organs- The tonsils, thymus and spleen. Are involved in specific immune responses.
Lysosomes- Small membrane-bounded spheres formed by the Golgi apparatus. Contain digestive enzymes which break down material transported into the cell via vesicles as well as worn-out organelles.

M

Male pronucleus- The head of the sperm once it has entered the egg and had its tail absorbed.
Malignant neoplasm- An abnormal mass of tissue formed from the uncontrolled division of cells. Also known as a malignant tumour.
Malignant tumour- An abnormal mass of tissue formed from the uncontrolled division of cells. Also known as a malignant neoplasm.
Mammalia- A class (taxonomic rank) that includes warm-blooded hairy creatures that produce milk.
Mandible- The bone that makes up the lower jaw.  It is the only bone in the jaw with a moveable joint.
Matrix- The name for the intercellular material inside tissues.
Maxilla- The bone that forms the upper jaw, as well as part of the mouth, eye sockets and nasal cavities.
Mediastinum- The space between the two lungs.
Meiosis- A type of cell division that results in four haploid "daughter" cells. Used to form the gametes.
Melanocyte- A pigment cell.
Melanoma- A type of cancer that forms from melanocytes. Grow and spread very quickly.
Menarche- The time at which a woman first begins to menstruate. Normally between 9-16 years of age.
Menisci (singular: meniscus)-  Articular discs in the knee joint. Consist of fibrocartilage which extends inwards from the articular capsule.
Menopause- The time at which menstruation no longer occurs. Normally occurs around 35 years after menarche, between the ages of 40 and 50.
Menstruation- The expulsion of blood, mucous secretions and cell debris from the uterine lining through the vagina. Occurs roughly once every month.
Mesenteric artery- An artery that takes blood to the intestines.
Messenger RNA- A type of RNA used to transfer the genetic code from the DNA to the ribosomes.
Metabolism- The chemical reactions that take place within cells.
Metacarpals- Bones in the palm of the hand.
Metaphase- The second stage of mitosis. During this stage, the chromosomes line up on the equator of the spindle. The centromere of each chromosome is attached to a spindle fibre.
Metastasis- The process in which malignant cells spread to other parts of the body, forming secondary tumours.
Metatarsals- Foot bones.
Microfilaments- One of the structures of the cytoskeleton. Moves materials around the cytoplasm or moves the entire cell.
Microtubules- One of the structures of the cytoskeleton. Keeps organelles in place or moves them around the cell.
Microvilli (singular: microvillus)- Small projections located on the villi.
Minerals- Elements such as calcium, ion, iodine, zinc and fluorine that are necessary for the body. Different minerals have different functions within the body.
Mitochondria (singular: mitochondrion)- The energy centres of the cell. They have two membranes, which contain enzymes which are involved in energy-releasing cellular reactions. The inner membrane has a series of folds (which the outer membrane lacks), increasing the surface area for chemical reactions.
Mitosis- A type of cell division which results in two diploid "daughter" cells.
Molars- Teeth used for crushing and grinding (along with the premolars). The cusps on the crowns of the molars fit into the depressions of the crowns of the molars on the opposite site, making crushing and grinding more efficient.
Monosaccharide- Simple sugars (e.g. glucose, fructose, galactose) that only consist of one ring of C, H and O atoms. Can combine to form disaccharides or polysaccharides.
Monounsaturated fat- A fat in which there is only one double bond between carbon atoms.
Morula- A ball of cells formed from the zygote dividing. It is roughly the same size as the original zygote as no new cytoplasm is produced, but has many more nuclei due to the increased number of cells.
Mountain sickness- Higher altitudes contain lower pressure air (i.e. fewer gas molecules in the same amount of space as compared to lower altitudes). People who aren't used to the lower pressures may feel sick as their bodies are unable to absorb enough oxygen. Also known as altitude sickness.
Mucosa- The innermost layer of the alimentary canal. In the oesophagus, it secretes mucus, making it easier for the food to move through. In the stomach, it secretes gastric juice, which contains digestive enzymes, among other things. The stomach mucosa can also secrete mucus to protect itself from the hydrochloric acid in the gastric juice. The small intestine mucosa has many folds as well as finger-like projections called villi, increasing surface area. It also contains glands that secrete intestinal juice.
Mucus method- A method of contraception that relies on observing changes in the mucus of the cervix.
Muscle tone- The partial contraction of skeletal muscles.
Muscular dystrophy- Inherited diseases in which individual muscle cells degenerate. Leads to a progressive reduction in the size of the skeletal muscle, an increase in connective tissue and possibly the replacement of muscle fibres with fatty tissue. There are two forms: the Duchenne form and the fascioscapulohumeral form.
Muscular endurance- The ability of a muscle to contract repeatedly or sustain a contraction for an extended period of time.
Muscular strength- The force that a muscle group can exert against a resistance.
Muscle tone- The maintenance of partial contraction of muscles.
Mutagens- Agents that can increase the rate at which mutations occur (though do not cause mutations). Include mustard gas, sulfur dioxide, X-rays, radiation, and so on.
Myocardial infarction- A complete stop in blood flow to a part of the heart muscle, resulting in death of the muscle in that area. This causes sudden and severe chest pain. Can heal if only a small area is affected; adverse effects and death can also occur. Symptoms include chest pain, pain radiating to the left arm, shoulder, neck or jaw, sweating, breathlessness, faintness and palpitations. Also known as a heart attack.
Myofibrils- Thread-like structures found within the sarcoplasm.

N

Nasal cavity- The part of the nose inside the skull.
Neck (part of tooth)- The part of the tooth between the crown and the roots.
Net diffusion- The overall movement of particles along a diffusion gradient.
Neurons- Nerve cells.
Non-specific urethritis (NSU)- An infection of the urethra. Can be caused by the Chlamydia bacteria, though there are many other causes.
Nuclear membrane- The membrane surrounding the nucleus. It is actually a double membrane- two membranes separated by a space.
Nucleic acids- Molecules consisting of chains of nucleotides. RNA (ribonucleic acid) has one chain, while DNA (deoxyribonucleic acid) has two chains.
Nuclear pores- Gaps in the nuclear membrane which allow substances to pass through.
Nucleolus- An area in the nucleus that contains RNA, which plays a role in synthesising proteins.
Nucleoplasm- The fluid inside the nucleus. Suspended in it are chromatin threads and the nucleolus.
Nucleotide- A small molecule consisting of a nitrogen base, a sugar and a phosphate group. RNA (ribonucleic acid) has ribose sugar, while DNA (deoxyribonucleic acid) has deoxyribose sugar.
Nucleus- One of the organelles of the cell. Nearly all cells contain one, though some contain more, and some don't have a nucleus at all. It is the largest organelle, is normally oval or spherical in shape, and is surrounded by a nuclear membrane. The nucleus is often thought of as the "control centre" for the cell as it contains DNA (deoxyribonucleic acid), which determine which proteins and enzymes a cell can make, which then determine which chemical reactions can take place in the cell.

O

Oblique muscle layer- A layer of muscles in the stomach that provide the stomach with more ways in which it can churn the food.
Oestrogen- One of the sex hormones in females.
Olfactory receptors- Nerve endings located in the upper part of the nasal cavity. Are sensitive enough to distinguish different smells.
Oogenesis- The process in which ova are produced.
Oogonia (singular: oogonium)- "Egg mother cells." Diploid cells that will eventually divide to form ova. Millions are already present at birth.
Oophorectomy- Removal of ovaries.
Opposability- The ability of the thumb to reach across and touch the tips of the other fingers of the same hand.
Organelles- Small structures within the cell that carry out various functions.
Origin- The end of the muscle attached to the stationary bone.
Osmosis- The diffusion of water across differentially permeable membranes (e.g. the membranes of cells).
Osmotic pressure- The pressure caused by osmosis when solutes that can't pass through a differentially permeable membrane are added.
Osteoarthritis- A much more common, but much less damaging form of arthritis (as opposed to rheumatoid arthritis). It involves deterioration of the articular cartilage, causing bony spurs to develop from the ends of the bone forming the joint. Due to these spurs, the space in the joint is decreased, which in turn restricts the movement of the joint.
Osteoblast- Bone-forming cell that allows bones to repair themselves after a fracture. Stimulated when the bone is used for support and movement.
Osteocyte- Bone cell
Osteoporosis- A gradual reduction in the rate of bone formation while the rate of bone absorption remains normal. This results in the bones becoming porous, fragile and relatively easily broken.
Ova (singular: ovum)- The female gametes.
Ovarian cyst- A fluid-filled tumour in the ovary that is usually not cancerous.
Ovary- The organ in which ova are produced. They are located within the body, on either side of the pelvic cavity, and are supported by ligaments.
Oviduct- A tube that carries the ovum from an ovary to the uterus. Also known as the Fallopian tube or uterine tube.
Ovulation- The expulsion of an ovum from the mature follicle into the uterine tube.
Oxyhaemoglobin- A bright red compound produced when oxygen and haemoglobin combine.
Oxytocin- A hormone secreted by the pituitary gland. Causes the small muscles around the milk-filled lobules in the breast to contract, pushing milk through the openings on the nipple.

Year 11 Human Bio Glossary F - J

Other glossary sections: (A - E) (K - O) (P - T) (U - Z)

F

Faeces (American: feces)- The fancy way of saying "poo." Contains stuff that didn't get digested, such as cellulose, bacteria, bile pigments and so on.
Fallopian tube- A tube that carries the ovum from an ovary to the uterus. Also known as the uterine tube or oviduct.
False ribs- Ribs that do not directly attach to the sternum by cartilage.
Fats- Lipids formed from condensation reactions between glycerol and fatty acids. Most fatty acids (98%) are triglycerides- formed from glycerol and three fatty acids. There are monoglycerides and diglycerides as well.
Fatty acds- Molecules that allow cells to make certain fats necessary for body functioning. May also contain fat-soluble vitamins, like vitamins A, D, E and K. They can be stored as a reserve of energy. They contain a lot of energy- 37kJ per gram. Can be found in butter, margarine, milk, cheese, oils etc.
Female pronucleus- The nucleus of the egg.
Femoral arteries- Arteries that take blood to the legs.
Femur- The upper leg bone.
Fetoscopy- A method used to check for birth defects. A small, telescope-like instrument is inserted into an incision made in the abdominal wall, allowing doctors to have a look at the developing foetus. Also allows doctors to take samples (of skin tissue, umbilical cord blood etc.) for further analysis.
Fibrillation- Uncoordinated contractions of individual muscle fibres. This prevents the muscle from contracting smoothly.
Fibrinogen- A plasma protein involved in blood clotting. These proteins make the blood sticky.
Fibrous capsule- The outer layer of the capsule surrounding freely moving (synovial) joints. It consists of dense, fibrous tissue, which is attached to the periosteum of the bones. It is strong yet flexible, allowing movement while resisting dislocation.
Fibrous joints- Joints where the bones are held in place by fibrous connective tissue. Very difficult to damage. Can be found between bones of the skull. Also known as fixed joints.
Fibula- The smaller of the two lower leg bones. It articulates with the tibia at the hip joint and with one of the ankle bones at its lower end.
Fimbriae- Small projections near the opening of the Fallopian tubes (on the ovary side) that help to guide the ovum into the tubes.
First-class proteins- Proteins containing sufficient quantities of essential amino acids. Same as complete proteins.
First polar body- The smaller product of the first meiotic division of a primary oocyte. Can divide into two additional polar bodies, but eventually all polar bodies will disintegrate.
Fixed joints- Joints where the bones are held in place by fibrous connective tissue. Very difficult to damage. Can be found between bones of the skull. Also known as fibrous joints.
Flagella- Tail-like structures that are longer than cilia. There are only one or two per cell. In humans, only sperm cells have flagella.
Flexibility- Range of motion about a joint.
Flexion- Movement causing the angle between bones to decrease (e.g. bending the knee).
Floating ribs- Ribs that don't attach to the sternum at all.
Foetus- The name for the unborn baby after it has grown limbs.
Follicle-stimulating hormone (FSH)- One of the gonadotropic hormones. In females, this stimulates the development of the ovarian follicle. Less FSH is secreted as oestrogen levels rise. In males, FSH stimulates the production of sperm.
Foramen magnum- The hole in the skull where the brain joins on to the spinal cord.
Foramen ovale- An oval opening between the two chambers of the heart of an unborn baby, allowing blood to flow directly from the right atrium to the left atrium.
Freely moveable joints- Joints with a relatively large range of movement. (Movement is, however, restricted by the shape of the bones.) Also known as synovial joints.
Friction ridges- Fingerprints. Increase friction between fingers and objects.
Frontal lobe- The front part of the cerrebrum. Involved in the higher functions of thinking, reasoning, planning and processing.
Functional foods- Foods with particular beneficial ingredients added to them, for example yoghurt containing probiotics, or margarine containing extra calcium.

G

Gallbladder- A small sac on the outside of the liver, where bile is stored and concentrated before travelling to the duodenum via the common bile duct.
Gamete intrafallopian transfer (GIFT)- A type of ART in which the eggs and sperm are mixed together immediately after the eggs have been collected, before being injected into the woman's uterine tubes. Success rates with this method are low.
Gametes- The sex cells (ova in females, sperm in males).
Gametogenesis- The process in which sex cells are produced.
Gastric glands- Glands in the gastric pits in the lining of the stomach. Secrete gastric juice.
Gastric juice- A juice secreted by the gastric glands in the stomach. Contains HCl, mucus and digestive enzymes.
Gastric pits- Narrow "pits" located in the mucosa (innermost layer) of the stomach. Contain gastric glands which secrete gastric juice.
Gastric protease- An enzyme that breaks proteins and other long chains of amino acids down into shorter chains, or polypeptides. Also known as pepsin.
Gastrocnemius- The most prominent of the two calf muscles.
Gene mutation- A change in a single gene caused by the DNA copying itself incorrectly during cell division.
Genes- Sections of DNA that determine the proteins to be formed.
Geriatrics- The area of medicine that deals with prevention and treatment of disease in older people.
Germ cells- Cells located in the ovaries that are enclosed in follicles. Eventually develop into ova.
Gerontology- The study of ageing, concerned with minimising the disabilities and handicaps of old age.
Gestation- The embryonic and foetal period.
Glandular epithelium- A type of epithelial tissue in which the cells secrete sweat, saliva, enzymes, hormones and so on.
Gliding joint- Joint in which movement can occur in any direction, hindered only surrounding ligaments or bones. Examples: between carpal bones, between tarsal bones, between the sternum and clavicle, between the scapula and clavicle
Globin- A protein found in haemoglobin.
Globulin- A type of plasma protein, some of which can act as antibodies when fighting diseases.
Glottis- The opening between the vocal cords.
Gluteus maximus- The largest of the gluteal muscles.
Gluteal muscles- Muscles that extend from the pelvis to the femur of each leg. Each has a "neck" that bends inwards so as to provide optimal leverage for the muscles that pull on it. They extend and rotate the thighs. The largest of these is the gluteus maximus.
Glycerol- An organic molecule containing three carbon atoms and three -OH groups.
Glycogen- The form in which carbohydrates are stored in the body. Can be converted into glucose and back again to maintain healthy blood glucose levels.
Glycolysis- The first stage of aerobic respiration. The glucose molecule is broken down in the cytoplasm into two molecules of pyruvic acid, simultaneously releasing two molecules of ATP.
Golgi apparatus- A series of flattened, membranous bags. Involved in packaging up proteins and so forth to prepare them for secretion from the cell. At the Golgi apparatus, molecules such as sugar, sulfate or phosphate are added, before the edges of the Golgi apparatus pinch off to form a vesicle (a liquid-filled sac) containing the proteins, which then travel through the cytoplasm to the cell membrane, where they then leave the cell.
Gonadotropic hormones- Hormones secreted by the pituitary gland that affect the gonads. Also known as gonadotropins.
Gonadotropins- Hormones secreted by the pituitary gland that affect the gonads. Also known as gonadotropic hormones.
Gonads- Sex organs.
Gonorrhoea- An STD that affects the mucous membranes of the excretory and reproductive systems, the rectum and occasionally the eyes. Can spread to other areas if untreated. In males, can cause a burning feeling in the penis, extreme pain when passing urine and a yellow discharge of pus from the penis. In females, can cause pus. Sterility can occur if the testes (in males) or oviducts (in females) are infected.
Graafian follicle- A mature follicle.
Granular leucocyte- A type of leucocyte that has granules suspended in the cell contents and "lobed" nuclei (several lobes connected by thin filaments rather than one massive lobe). Also known as a granulocyte.
Granulocyte- A type of leucocyte that has granules suspended in the cell contents and "lobed" nuclei (several lobes connected by thin filaments rather than one massive lobe). Also known as a granular leucocyte.
Gross to specific pattern- A pattern involved in motor development in which larger muscle movements are learned before finer movements like picking up objects with the fingers.
Guanine- One of the nitrogen bases present in DNA and RNA. Pairs up with cytosine.

H

Haem- A component of haemoglobin. Consists of an iron atom which can combine with an atom of oxygen.

Haemoglobin- A compound found in erythrocytes (red blood cells) which is required for carrying oxygen around the blood. It is made up of a protein called globin combined with four haem groups. When the iron of the haem groups combines with oxygen, haemoglobin turns red.
Hamstrings- One of the muscle groups of the thigh. Bends the knee and extends the thigh backwards.
Haploid cell- A cell containing only half a set of chromosomes (in humans, haploid cells have 23 chromosomes).
Haversian canal- A component of Haversian systems. Contains at least one blood capillary and possibly nerves and lymph capillaries as well.
Haversian system- Structures that make up compact bone. Consist of a Haversian canal, concentric layers of lamellae, lacunae (which hold the bone cells) and canaliculi (small canals between the lacunae). Haversian systems are positioned parallel to the long axis of the bone, providing maximum strength.

Heart attack- A complete stop in blood flow to a part of the heart muscle, resulting in death of the muscle in that area. This causes sudden and severe chest pain. Can heal if only a small area is affected; adverse effects and death can also occur. Symptoms include chest pain, pain radiating to the left arm, shoulder, neck or jaw, sweating, breathlessness, faintness and palpitations. Also known as a myocardial infraction.

Hepatic artery- An artery that takes highly oxygenated blood to the liver.

Hepatic portal vein- A vein that takes nutrients from the alimentary canal to the liver by first passing through the capillaries of the stomach and intestines.
Hepatitis B (HBV)- A virus that affects the liver. Symptoms include fatigue, fever, headache, nausea, vomiting, muscle aches and jaundice.
Hinge joint- Joint in which one bone has a convex surface which slots into the concave surface of the other. Examples include the elbow and the knee.
Homeostatic capacity- The ability to maintain a constant internal environment while other environmental factors, such as temperature, might be changing.
Homeothermic- Maintains a constant body temperature.

Hominidae- A family within the Hominoidea superfamily that includes extinct ancestors of humans as well as modern humans.

Hominoidea- A superfamily within the Anthropoidea suborder that does not include animals with external tails. Only includes apes and humans.

Homo- A genus within the Hominidae family that includes some extinct ancestors of humans as well as modern humans.

Homo sapiens- Modern humans
Human chorionic gonadotropin (HCG)- A hormone produced in the developing placenta in a pregnant woman. Maintains the corpus luteum.
Humerus- Upper arm bone.

Hydrochloric acid (HCl)- An acid that kills many of the bacteria that enter the stomach. It is also necessary for activating pepsinogen, a digestive enzyme found in gastric juice. It also lowers the pH of the stomach.
Hymen- A fold of tissue that partially covers the external opening of the vagina.

Hypertension- High blood pressure.
Hysterectomy- Removal of the uterus.

I

Immunoglobulin- A transfusion containing antibodies against particular diseases (e.g. HRIG is human rabies immunoglobulin).
Implantation- The process in which the outer cells of the blastocyst secrete enzymes, allowing it to enter the endometrium and attach itself there.
Incisors- Teeth used for biting or cutting.
Inclusions- Chemical structures within cells that are not considered to be part of the structure of the cell (e.g. haemoglobin in red blood cells).
Incomplete proteins- Proteins that do not contain sufficient quantities of essential amino acids. Same as second-class proteins.
Inferior vena cava- One of the main veins of the body. Takes blood from the lower parts of the body to the right side of the heart.
Initiation stage- The first stage of the development of a tumour. Some cells are changed irreversibly from exposure to the carcinogen.
Inner cell mass- A bunch of cells attached to one side of the blastocyst. This will become the embryo, while the outer cell mass will become the placenta.
Insertion- The end of the muscle attached to the moving bone.
Insoluble fibre- Food, such as cellulose, that cannot be digested by humans, but stimulates the contraction of the muscular walls of the intestine. Also known as roughage.
Inspiration (respiration)- Inhalation/breathing in.
Intellectual functioning- The ability to perform numerical skills, verbal skills etc.
Intercellular fluid- Fluid found between cells in the tissues. Also known as tissue fluid or interstitial fluid.
Intercostal muscles- Muscles between the ribs. There are external and internal intercostal muscles, which are positioned at right angles to each other. The external intercostal muscles can contract to move the rib cage upwards and outwards, while the internal intercostal muscles can contract to pull the ribs closer together.
Interphase- The period between divisions, during which the DNA replicates itself.
Interstitial cells- Cells located between the seminiferous tubules in the testes. Secrete testosterone.
Interstitial fluid- Fluid found between cells in the tissues. Also known as tissue fluid or intercellular fluid.
Intestinal juice- A digestive juice secreted by glands in the mucosa of the small intestines. It contains many enzymes. Some (such as lactase, sucrase etc.) break specific disaccharides down into monosaccharides. Peptidases break down peptide chains and lipases break down fats.
Intracellular fluid- Fluid inside cells.
Intracytoplasmic sperm injection (ICSI)- A type of ART in which a single sperm is injected into a single egg through a micropipette and the embryo is transplanted into the woman's uterus.
In-vitro fertilisation (IVF)- A type of ART in which the ovum is taken from the mother, fertilised outside the body, and transplanted back into the uterus.
Involuntary muscles- Muscles in the internal organs. Do not have striations. Also known as smooth muscles.

J

Year 11 Human Bio Glossary A - E

Sooooo I decided that now I've gone through the book, I'd create a glossary. This is for two reasons: 1) it's a different format of presenting the information, and I find that it often helps to see information in at least two different formats and 2) it could be a useful resource for you to create your own flashcards or study tools. I'll try not to go into too much detail in the glossary- if you need extra details on anything, go to the relevant post(s) (there's a search bar at the top if you haven't noticed it already), Google it, or look it up in your textbook. NOTE: I don't know what the "official WACE Human Bio definition" is for anything, so don't copy what I have to say verbatim. Understanding the concepts is more important than memorisation anyway.

With regards to flashcards, I am overwhelmingly in favour of flashcard apps like Anki (there are loads of others, like SuperMemo, Repetitions and so on- I just mentioned Anki first because it's probably the most well-known), since they save you from having to physically make flashcards and also they use spaced repetition to help you remember more things with less effort. Also, you can download these apps onto your phone (iOS users have to pay quite a bit for Anki though- might be time to switch to Android eh?) so that wherever you've got your phone, you've got a very useful study tool. Of course, if you prefer physical flashcards, that's your call.

Other sections of the glossary: (F - J) (K - O) (P - T) (U - Z)

A

Abduction- Movement away from the midline of the body.
Abnormal uterine bleeding- Very heavy periods, periods that are too frequent, bleeding during non-menstrual phases and bleeding after menopause.
Accessory ligaments- Ligaments holding together bones in many joints.
Acetabulum- A socket located in each pelvic bone. Forms part of the hip joint.
Active transport- Energy is used in order to forcibly absorb substances against a concentration gradient (i.e. force a substance to move from a place of low concentration to a place of higher concentration).
Adduction- Movement towards the midline of the body.
Adenine- One of the nitrogen bases present in DNA and RNA. Pairs up with thymine.
Adipose tissue- A type of connective tissue that cushions vital organs and restricts heat loss. Consists of cells that contain large globules of fat with the cytoplasm forming a thin layer on the outside.
Adolescent growth spurt- The period during which adolescents rapidly grow taller.
Aerobic respiration- Cellular respiration requiring oxygen.
Afterbirth- The placenta, umbilical cord, amnion and chorion which are expelled after birth.
Agonist- The muscle in the pair that carries out the desired action. Opposite to this is the antagonist. The agonist is also known as the prime mover.

Agranular leucocyte- A leucocyte that doesn't have any granules in its cell contents and usually has a spherical nucleus. Includes monocytes and lymphocytes.

Albumin- A type of plasma protein which is like the proteins found in egg whites.

Alimentary canal- The tube in which digestion takes place. Runs from the mouth to the anus and includes the pharynx, oesophagus, stomach and intestines.
Allantois- One of the embryonic membranes. Will become part of the umbilical cord.
Altitude sickness- Higher altitudes contain lower pressure air (i.e. fewer gas molecules in the same amount of space as compared to lower altitudes). People who aren't used to the lower pressures may feel sick as their bodies are unable to absorb enough oxygen. Also known as mountain sickness.
Alveoli (singular: alveolus)- Tiny air sacs that make up most of the area of the lung. Exchange of gases between the blood and the lungs takes place here, as the alveoli have very thin walls (one cell thick). They contain thin layers of moisture, allowing them to dissolve gases.

Amino acids- The building blocks of proteins. There are about 20 different amino acids. Some are part of the structural material in the cell and some are enzymes in cellular reactions, while excess proteins are either converted to carbohydrates to be used as energy or stored as fats.
Amniocentesis- A method used to check for birth defects. 10-20mL of amniotic fluid containing living cells from the foetus is removed. The cells can be checked for abnormalities in biochemistry or in number/structure of the chromosomes.
Amnion- One of the embryonic membranes. Secretes amniotic fluid into a cavity surrounding the embryo. Will eventually fuse with the inner layer of the chorion.
Amniotic fluid- A fluid that protects the embryo from physical injury and maintains a constant temperature while allowing the foetus to move around. Expands while the foetus grows and ruputures just before childbirth.
Anabolism- Chemical reactions that create large molecules from several smaller ones.

Anaemia- A condition in which the number of red blood cells or the concentration of haemoglobin is reduced, resulting in inadequate oxygen supply to the tissues, which in turn results in symptoms such as fatigue and intolerance to cold.
Anaerobic respiration- Cellular respiration without oxygen.

Anal sphincter- The muscle around the anal opening that controls bowel movements.
Anaphase- The stage of cell division where the chromatids begin to separate off into different parts of the cell.

Angina- Chest pain normally caused by atherosclerosis of the coronary arteries.

Animalia- The kingdom (highest taxonomic rank) that contains animals (including humans).
Antagonist- The muscle within the pair that does not cause the desired action. Opposite of this is the agonist.
Antagonists- Pairs of muscles. The two muscles in the pair carry out opposite effects.
Anterior tibialis- A muscle located at the front of the lower leg. Allows us to point our toes upwards, taking weight onto the heels.

Anthropoidea- A suborder within the Primates order which consists of "human-like primates" such as monkeys, apes and humans.

Antigens- Substances that can stimulate the formation of antibodies. Red blood cells can contain antigen A and/or B, or neither antigen A or B.

Anus- The opening at the end of the rectum. Faeces pass through here.

Aorta- The main artery of the body. Takes blood from the left side of the heart to other organs of the body.

Appendicitis- Inflammation of the appendix. Could be caused by blockage of the appendix by faecal matter or a foreign body, but there may be other causes as well.
Appendicular skeleton- The bones that make up the ribs as well as the shoulders and hips.

Appendix- A part of the large intestine located at the end of the caecum opposite the entrance to the colon.
Arboreal- Live in trees.

Arteries- Relatively large blood vessels that take blood away from the heart. They have thick, strong walls with smooth muscle that allows them to stretch and relax to maintain blood pressure.

Arterioles- Small arteries. Like arteries, they have thick, strong walls with smooth muscle, allowing them to stretch and relax in order to maintain blood pressure.

Arteriosclerosis- Hardening and narrowing of the arteries.
Arthritis- Inflammation of the joints.
Articular cartilage- Cartilage located on the epiphyses of the bones, providing smooth surfaces for movement.
Articular disc- A structure that divides the synovial cavity into two, allowing synovial fluid to be directed to areas of greatest friction.
Articulate- When bones are positioned in such a way that they can move relative to each other, they are said to articulate.
Artificial insemination by donor (AID)- A reproductive technology in which the woman accepts semen donated by an unknown man.

Ascending colon- The part of the colon that goes from the caecum upwards.
Assistive reproductive technology (ART)- Reproductive technology which involves the fertilisation of an egg and sperm outside of the uterus. The resulting embryo is then transplanted into the woman's uterus. There are several different types.
Asthma- An allergic response which results in the muscles surrounding the bronchioles going into spasm (sudden involuntary contractions) and excessive mucus being secreted, causing difficulties in breathing.

Atherosclerosis- A type of arteriosclerosis in which hard, calcified areas cause obstructions, resulting in the artery walls losing their elasticity.

Atrial systole- A stage of the cardiac cycle, lasting roughly 0.1 seconds. During this phase, the atrium contracts, forcing blood into the ventricles. Meanwhile, the ventricles stay relaxed, ready to receive the blood rushing in.

Atrioventricular valve- A valve in the heart that allows blood to pass from atrium to ventricle, but not the other way. Consist of flaps as well as chordae tendinae. The atrioventricular valve of the left side has two cusps (and is thus called the bicuspid valve), while that of the right side has three cusps (and is thus called the tricuspid valve).

Atrium- The first chamber that the blood enters when it enters the heart through the veins. Has relatively thin walls as incoming blood is low-pressure.
Atrophy- The decrease in size of a muscle. Normally happens in muscles that aren't used or are only used for very weak contractions.

Autologous transfusion- A transfusion in which the patient's own blood (donated in advance) is used.
Axial skeleton- The bones surrounding the central "axis" of the body (i.e. the skull, backbone and ribs)

B

Ball-and-socket joint- A joint in which one bone has a spherical head, while the other has a kind of cup-like cavity for the spherical head to fit into. Allows movement in all directions. Examples: shoulder joint, hip joint
Balloon angioplasty- A treatment for atherosclerosis in which a patient is first given drugs that help to dissolve clots, and then a tube with a tiny balloon at the tip is inserted into the patient's arteries. The balloon is inflated to cause the artery to expand and the plaque to loosen from the wall.
Basal metabolic rate (BMR)- The amount of energy required when resting.
Belly- The middle section of a muscle.
Benign tumour- A tumour that does not spread to other parts of the body, as its cells cannot invade normal tissues, blood vessels or lymph vessels.
Bicuspid valve- The atrioventricular valve on the left side of the heart, so called due to its two cusps.
Bile pigments- A component of bile. Bile pigments are the end result of red blood cells breaking down. They have no digestive function and are excreted in the faeces.
Bile salts- A component of bile that is necessary for emulsifying fat (breaking it up into lots of pieces that can't be mixed back together), increasing the surface area, so that enzymes can break fat down more efficiently.
Bipedal- Walks on two legs.
Birth canal- The curved passage made up of the uterus, cervix and vagina following the dilation of the cervix. The baby travels through here to be born.
Blastocyst- A hollow ball of cells formed around 5 days after fertilisation (1-2 days after the morula stage). One side has a bunch of cells collectively known as the inner cell mass.
Blood clotting- A series of processes that allow blood clots to form. Also known as coagulation.
Bolus- A lump of food held together by mucus in the saliva.
Bonding- A term used to refer to the love and affection between parent and child.
Brachialis- A muscle that lies beneath the biceps. Allows us to flex our forearms.
Breech presentation- The foetus is positioned with buttocks down rather than head down at birth.
Bronchi (singular: bronchus)- Tubes that bring air in and out of the lungs. They have cartilage like the trachea, and a ciliated mucous membrane.
Bronchioles- Smaller bronchi that lack cartilage and cilia.
Bronchitis- An irritation that causes an increase in mucus production in the bronchi and bronchioles, which can result in an accumulation of mucus which can be cleared by coughing.
Bulbo-urethral glands- Two small yellow glands located beneath the prostate gland. Secrete a clear mucus which mainly acts as a lubricant, thogh a small amount does get inclued in the semen as well. Also known as the Cowper's glands.
Bursae- Little sacs of synovial fluid. Only present in some joints. Bursae are positioned in such a way to prevent friction in certain parts of the joint.

C

Caecum- A 6cm pouch at the beginning of the large intestine. It ends in the appendix.
Calcanean tendon- The tendon at the end of the gastrocnemius muscle. Also known as the Achilles' tendon.
Calcaneus- The largest of the ankle bones. Also known as the "heel bone."
Canaliculi- Small canals that run between lacunae in compact bone. Allow materials to be passed between cells.
Cancellous bone- Porous bone tissue that contains many large spaces. Also known as spongy bone.
Canines- Teeth used for tearing and ripping.
Capillaries- Microscopic blood vessels that form complex networks, allowing them to carry blood to nearly every cell. They have very thin walls (only one cell thick), allowing substances to diffuse in and out of them more easily.
Carbaminohaemoglobin- A compound formed when carbon dioxide combines with the globin part of the haemoglobin molecule. It can break down to allow carbon dioxide to diffuse into the alveoli.
Carbohydrates- Chains of sugars that contain carbon, hydrogen and oxygen. They are necessary for providing energy to the body cells. Excess carbohydrates are stored as glycogen in the liver and muscles, but if there's too much then the remaining excess gets converted into fat.
Carbon monoxide poisoning- Carbon monoxide (CO) can combine with haemoglobin 250 times more readily than oxygen can. When CO combines with haemoglobin, the oxygen-carrying capacity of the blood is reduced.
Carcinogen- A factor that triggers the growth of a tumour.
Carcinoma- A type of cancer that forms from epithelial cells on the inner and outer surfaces of the body. Around 90% of cancers are carcinomas.
Cardiac arrest- The heart pumps little to no blood. Can result in death within minutes.
Cardiac cycle- A fancy way of saying "heartbeat."
Cardiac muscle- Muscle making up the wall of the heart. Has cross-striations like skeletal muscle, but unlike skeletal muscle, cardiac muscles branch to form a network.
Carotid arteries- Arteries that take blood to the head and neck.
Carpals- Wrist bones. There are eight of them in each wrist.
Cartilage- A type of connective tissue that provides structural support while still providing some flexibility. Has fibres embedded in a firm matrix which also contains spaces for the cartilage cells.
Cartilaginous joints- Joints in which bones are held together by cartilage. Slight movement can occur, but not a lot. Also known as slightly moveable joints.
Castration- Removal of the testes.
Catabolism- Chemical reactions that break down larger molecules into smaller ones.
Cell membrane- A structure that separates the cell from neighbouring cells and the external environment. It is made up of a double layer of lipid molecules as well as various proteins associated with the lipids. Allows some substances to get through but not others. Also known as the plasma membrane.
Cellular respiration- A metabolic process in which the organic molecules from the food are broken down to release energy for the cells.
Cellulose- A long-chain carbohydrate that can be found in foods of plant origin, particularly unrefined foods.
Cementum- The outer layer of the tooth on the root side. Anchors the teeth to the jaw bone.
Centrioles- A pair of cylindrical structures, which are made up of rings of very fine tubules. The centrioles are located at right angles to each other. They are located near the nucleus and are involved in cellular reproduction
Centromere- The point at which two chromatids join in a chromosome.
Cephalocaudal pattern- A pattern involved in motor development. Movements of the upper parts of the body develop before those of the lower parts of the body.
Cerebral cortex- The outer region of the brain. Responsible for complex functions such as vision, memory, reasoning and manipulative ability.
Cerebral haemorrhage- Bleeding that occurs at a weak point in one of the cerebral arteries.
Cervix- A structure at the lower end of the uterus that protrudes into the vagina. Contains a narrow passage known as the cervical canal.
Chlamydia- An STD caused by a bacteria. Affects many parts of the body.
Chordata- Our phylum. Contains creatures that have spinal cords running down their backs, attached to a brain at one end (a.k.a. a "dorsal nerve cord").
Chordae tendinae- Fibrous chords that stop the flaps of the atrioventricular valve from swinging too far.
Chorion- A membrane that develops from the outer cells of the blastocyst and a layer of mesodermal cells. Surrounds the embryo and the other three embryonic membranes. Eventually becomes the main part of the foetal portion of the placenta. Produces HCG.
Chorionic villi- Finger-like projections that are formed from the cells of the chorion. Contain numerous blood vessels. Provide a large surface area to make contact with the mother's blood, allowing nutrients, oxygen and waste products to diffuse back and forth between the mother's blood and the baby's blood. Active transport may also be used.
Chorionic villus sampling (CVS)- A method used to check for birth defects. Foetal cells from the chorion are checked for abnormalities.
Chromatid- A structure in a chromosome. There are two chromatids in a chromosome.
Chromatin- Strands of DNA.
Chromosomal mutation- A mutation involving a cell receiving too many or too few chromosomes, or parts of chromosomes.
Chylomicrons- Tiny droplets that enter the lacteals, formed from fatty acids and glycerol recombining to form triglycerides which are then coated with protein.
Chyme- A soupy liquid formed after the food has been digested in the stomach.
Cilia- Hair-like projections located in the mucous membrane of the lower part of the nasal cavity, in the trachea and in the bronchi. Beat back and forth in order to push dust etc. towards the throat. As well as moving substances over cells, cilia can also move the whole cell.
Circular muscle- Muscle in which the fibres are arranged in a circle. Can be found in the alimentary canal.
Clavicle- Collar bone.
Cleavage- The process in which the zygote divides repeatedly to form a ball of cells called a morula.
Cleft lip- A birth defect in which the upper lip is split.
Cleft palate- A birth defect that occurs when the bones of the hard palate (the front part of the roof of the mouth) don't come together before birth. Associated with cleft lip.
Clitoris- A small structure located within the folds of the labia minora (in females). Contains erectile tissue, blood vessels and nerves.
Clot- Formed by cells trapped in the blood by threads of insoluble protein. Stops too much blood from flowing out of a torn blood vessel.
Clot retraction- A process in which the threads of insoluble protein making up a clot contract, becoming denser and stronger and pulling the edges of the blood vessels together. Serum is squeezed out during this process. After clot retraction, the clot dries and forms a scab, protecting the wound from infections.
Clotting factors- Chemical substances in the plasma that allow threads of insoluble protein to form, which trap cells, forming a clot.
Coagulation- A series of processes that allow blood clots to form. Also known as blood clotting.
Co-factors- Ions or non-protein molecules necessary for enzyme functioning.
Coitus- Sexual intercourse.
Coitus interruptus- An extremely unreliable form of contraception involving the man removing his penis before ejaculation.
Colostrum- A watery, yellowish-white fluid secreted by the breasts. Has a similar composition to milk, but contains little to no fat, and a high content of the mother's antibodies, which are then absorbed by the infant's intestine to give the baby temporary immunity to certain diseases.
Columnar cells- Column-shaped cells.
Common bile duct- A duct through which pancreatic juice and bile pass in order to get to the duodenum.
Compact bone- A type of compact tissue that is found in bones.
Complete proteins- Proteins containing sufficient quantities of essential amino acids. Same as first-class proteins.
Concentration gradient- The difference in concentration that allows diffusion to occur. Same as diffusion gradient.
Conchae- The "shelves" within each chamber of the nasal cavity.
Congenital disorder- A disease or defect which is present at birth due to either defective genes or environmental factors.
Congestive heart failure- The heart is too weak to pump sufficient amounts of blood. Also known simply as "heart failure."
Connective tissue- Tissue that binds and supports the other tissues of the body.
Convulsions- Violent, involuntary contractions. May be caused by muscle fibres receiving impulses from nerves, which in turn might have been stimulated by fever, poisons and so on.
Corona radiata- A layer of cells surrounding the ovum prior to fertilisation. The cells are held together by an acid, which has to be broken down by the enzymes contained within the heads of the sperm cells.
Coronary artery- An artery that takes blood to the heart itself.
Coronary heart disease- A disease in which atherosclerosis in the coronary arteries restricts the supply of blood to the heart muscle so that there might not be enough oxygen supply to the heart.
Corpus albicans- A fibrous mass of scar tissue formed after the corpus luteum degenerates.
Corpus luteum- The cream coloured body formed when the blood within a ruptured Graafian follicle clots and is absorbed by the remaining follicle cells. Secretes hormones that influence the development of the lining of the uterus.
Cortex- The outer portion of the brain. Has a lot of folds, called convolutions, which increase the surface area of the brain.
Cowper's glands- Two small yellow glands located beneath the prostate gland. Secrete a clear mucus which mainly acts as a lubricant, though a small amount does get included in the semen as well. Also known as the bulbo-urethral glands.
Cramps- Sustained involuntary muscular contractions that lack even partial relaxation.
Cranium- The part of the skull used for housing the brain.
Crown- The part of the tooth that is visible.
Cryoprecipitate- A transfusion created by freezing the plasma and allowing other substances to thaw out. Contains substances necessary for blood clotting.
Cuboidal cells- Cube-shaped cells.
Cytoplasm- Fluid within the cell. It is 75% to 90% water. Inorganic materials and most carbohydrates are dissolved in it, while other organic compounds such as proteins and lipids are simply suspended in it.
Cytosine- One of the nitrogen bases present in DNA and RNA. Pairs up with guanine.
Cytoskeleton- A structure that gives the cell its shape and assists the cell in moving. Consists of microtubules and microfilaments.

D

Daughter cell- A term used to refer to the new cells after cell division has occurred.
Dead space (respiratory system)- The interior of the organs of the respiratory system that are not involved in exchange of gases.
Deamination- A process through which excess amino acids are converted to carbohydrates. In this process, the -NH2 amine group is removed and converted to ammonia (NH3), which is then converted to urea. Urea is then removed from the blood by the kidneys before being excreted in urine.
Deciduous teeth- Baby teeth (the first set of teeth that you have).
Defecation- A fancy way of saying "shitting."
Dense connective tissue- A type of connective tissue that supports and connects other tissues. Stronger than loose connective tissue, making it more suitable for joining tendons to bones and so on.
Dentine- A layer of the tooth below the enamel and cementum. It is hard and bone-like and comprises much of the tooth.
Deoxygenated blood- Blood that has a lower concentration of oxygen. It is dark red in colour, as haemoglobin is dark red.
Deoxyribonuclease- A digestive enzyme in the pancreatic juice that breaks down DNA.
Descending colon- The third part of the colon. Goes down towards the rectum and anus.
Diaphragm- The muscle separating the thoracic and abdominal cavities. Can contract and relax to alter the volume of the thoracic cavity.
Diaphysis-The shaft of a typical long bone.
Diastole- The heart muscles are relaxed, allowing blood to flow into the atria and/or ventricles.
Differentially permeable membrane- A membrane that allows some substances to pass through but not others.
Differentiation- The specialisation of different cells to carry out different functions.
Diffusion- The spreading out of the particles of a gas or liquid over a given area so that they become evenly distributed.
Diffusion gradient- The difference in concentration that allows diffusion to occur. Same as concentration gradient.
Dipeptide- Two amino acids joined together.
Diploid cell- A cell containing a full set of chromosomes (46 in humans).
Disaccharide- Two simple sugars (monosaccharides) joined together. One example is sucrose.
Dislocation- A bone is displaced, and ligaments, tendons or capsules are torn. Symptoms include temporary paralysis of the joint, pain, swelling and occasionally shock.
Dorsal nerve chord- A spinal cord that runs down the back of an animal attached to its brain at one end. Shared by all creatures in the phylum Chordata.
Double circulation- The type of circulation used all birds and mammals, including humans. In this type of circulation, the blood is pumped by the heart twice in each circuit, keeping the blood moving rapidly and stopping it from losing too much pressure.
Down syndrome- A birth defect caused by having three of the chromosome number 21. Symptoms include mental retardation and malformation of the heart, ears, hands and feet. The risk increases as the mother reaches the end of her child-bearing period. Also known as trisomy-21.
Ductus arteriosus- The lung bypass present in unborn babies. Takes blood from the pulmonary artery to the aorta. Turns into fibrous tissue within a few weeks of birth due to the reduced amount of blood flowing through it.
Ductus venosus- The liver bypass. A vein in unborn babies that allows blood to bypass the liver. Blood stops flowing through the ductus venosus after birth, causing it to constrict until it is closed off, forcing all blood to pass through the liver instead.
Duodenum- The first C-shaped curve of the small intestine. It is about 25cm long.
Dysmenorrhoea- Painful menstruation caused by strong contractions of the uterus.

E

Ectopic pregnancy- A pregnancy where the blastocyst implants itself somewhere other than the uterus. Can be serious, causing internal bleeding or damage to the Fallopian tubes.
Ejaculation- Rhythmic contractions of the epididymis, the vas deferens, the seminal vesicles and the prostate gland, which push the sperm-containing semen out of the body.
Elasticity- The ability of muscles to return to their original length after being stretched.
Embryo- An organism at the stage between implantation of the blastocyst in the uterus and the development of limbs. Humans remain embryos for around two months before becoming a foetus.
Emphysema- Caused by long-term exposure to irritating particles. The particles damage the alveoli, which lose their elasticity, are replaced with fibrous tissue, and may break down. The loss of elasticity means that the lungs are constantly inflated, which then means that exhalation requires voluntary effort.
Enamel- The outer layer of the tooth on the crown side. It is the hardest substance in the body and is used to protect the teeth.
Endocrine gland- A gland that secretes substances directly into the blood or into the tissue fluid.
Endocytosis- A method of absorbing substances. The outer membrane folds around the substance in question, leaving the substance floating around the cytoplasm in a liquid-filled sac called a vesicle.
Endometrium- The soft mucous membrane lining of the uterus. Protects and nourishes the foetus during pregnancy.
Endoplasmic reticulum- Pairs of parallel membranes that extend through the cytoplasm and connect to the cell membrane and nuclear membrane. There are two types: rough (granular) endoplasmic reticulum and smooth (agranular) endoplasmic reticulum. The main difference is that the former has ribosomes attached to it, while the latter does not. The membranes of the endoplasmic reticulum is thought to provide a surface where chemical reactions can take place, while the channels are for storing or transporting molecules.

Enzyme- Organic catalysts (i.e. they speed up the reactions of living organisms without being consumed in the reaction). They are proteins.

Enzyme-substrate complex- Formed from the reaction with an enzyme and a substrate.
Epididymis- A tubule in which sperm are stored for up to a month while they mature.
Epididymitis- Pain and swelling of the epididymis.
Epiglottis- A flap of cartilage located at the entrance to the larynx. It closes the glottis during swallowing, stopping food from passing into the trachea and lungs.
Epiphyses (singular: epiphysis)- The ends of bones.
Epithelial tissue- Tissue used to cover body surfaces and line body cavities and ducts. Its functions include absorption, secretion and protection, depending on the location of the tissue in the body. Also known as the epithelium.
Epithelium- Tissue used to cover body surfaces and line body cavities and ducts. Its functions include absorption, secretion and protection, depending on the location of the tissue in the body. Also known as the epithelial tissue.
Erectile tissue- A type of connective tissue in the penis. Has a very rich blood supply. Contains a number of sponge-like spaces, which can fill with blood, causing an erection.

Erythrocytes- Blood cells that transport oxygen to the cells. They are red in colour, hence their other, more common name, red blood cells.

Essential amino acids- Amino acids that cannot be produced in the body. There are nine of these.
Eustachian tube- A tube that leads to the inner ear.
Exocrine gland- A gland that secretes substances outside the body, or onto a body lining.
Exocytosis- A method of eliminating substances from the cell. Vesicles containing the unwanted substances are pushed out of the cell.
Expiration- Exhalation/breathing out.
Extensibility- The ability of muscles to be stretched.
Extension- Movement causing the angle between bones to increase.

Extracellular fluid- Fluid outside the cells. Includes tissue fluid and plasma.