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.
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