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.