# Anatomy and Physiology of Animals/Glossary/A-B

A-B | C-D | E-F | G-H | I-J | K-L | M-N | O-P | Q,R,S | T,U,V,W,X,Y,Z
| Word | Meaning |
| A | |
| Abdomen | The part of the body below the diaphragm |
| Abomasum | The final compartment of the stomach of ruminants. This the ‘true’ stomach where muscular walls churn the food and gastric juice is secreted |
| Absorption | Passage of digested food from the gut into the blood |
| Accessory gland | A gland that produces secretions that make up the liquid portion of semen |
| Acetylcholine | A neurotransmitter released at a synapse |
| Acoustic | Relating to sound |
| Active transport | The movement of substances across a membrane against the concentration gradient. Requires energy |
| Adipose tissue | Connective tissue in which the cells are filled with fat or lipid |
| Adrenal cortex | Outer portion of adrenal gland |
| Adrenal medulla | Inner portion of adrenal gland |
| Albumin | The most common of the proteins in the plasma |
| Aldosterone | The hormone produced by the adrenal cortex |
| Alimentary | Concerning nutrition |
| Alimentary canal | The long canal from the mouth to the anus through which food passes as it is digested and absorbed |
| Alkaline | Containing few hydrogen ions. pH above 7 |
| Alveolus | An air sac in the lung, where gas exchange takes place |
| Amino acids | Molecules containing nitrogen that are the building blocks of proteins |
| Amphibian | Vertebrate Class containing the frogs and toads |
| Amylases | Enzymes that split carbohydrates like starch and glycogen into monosaccharides like glucose |
| Anaemia | A condition involving a low number of red blood cells or haemoglobin in blood |
| Antagonistic muscles | A pair of muscles that work together such that as one contracts the other relaxes and vice versa. |
| Anterior | Nearer to the front of the body (usually used in human anatomy) |
| Anterior pituitary gland | Anterior portion of pituitary gland |
| Antibodies | Proteins made in response to a stimulating molecule called an antigen. The basis for the immune response |
| Anticoagulant | A substance that prevents blood clotting |
| Antidiuretic | A substance that inhibits urine production |
| Antidiuretic hormone | A hormone produced by posterior pituitary gland that stimulates water reabsorption from the kidney tubule |
| Antigens | A substance that stimulates the body to produce an antibody |
| Anus | The opening at the lower end of the rectum through which solid waste is eliminated. |
| Aorta | The main artery to body and head from heart |
| Apex | The pointed end of a cone shaped structure e.g. heart |
| Appendage | A structure attached to the body |
| Aqueous humor | The watery fluid that fills the anterior chamber of the eye |
| Arteriole | A small, almost microscopic, artery |
| Artery | A blood vessel that carries blood away from the heart |
| Articulation | The point of contact between bones. Where they move against each other |
| Appendage | A structure attached to the body |
| Aqueous humor | The watery fluid that fills the anterior chamber of the eye |
| Arteriole | A small, almost microscopic, artery |
| Artery | A blood vessel that carries blood away from the heart |
| Articulate | To move against each other - as of bones |
| Articulation | The point of contact between bones. Where they move against each other. A joint. Point of contact between 2 bones |
| Atlas | First cervical vertebra |
| Atom | A unit of matter that comprises a chemical element |
| Atrioventricular valve | A valve that prevents blood flow backwards from ventricle to atrium |
| Atrium (pl. atria) | One of two cranial chambers of heart |
| Auditory ossicle | One of 3 small bones in middle ear |
| Autonomic nervous system | The part of the vertebrate nervous system that innervates smooth and cardiac muscle and glandular tissues and governs involuntary actions. Consists of the sympathetic nervous system and the parasympathetic nervous system. |
| Axillary lymph node | A lymph node under junction of forelimb and body |
| Axis | The second cervical vertebra |
| Axon | A long extension from the neuron that carries nerve impulses away from the cell body |
| B | |
| Ball and socket joint | A synovial joint where rounded end of one bone fits into cup-shaped depression of another |
| Barb | The part of the feather that sticks out of the shaft |
| Barbules | The parts of a feather that grow out of the barbs. They have hooks and rolled edges to lock the barbs together |
| Basement membrane | The thin membrane between epidermis and dermis |
| Basophil | A white blood cell with granules in the cytoplasm |
| Biceps | The muscle that extends from the shoulder to the elbow responsible for flexing the forearm |
| Bilateral | Including both sides |
| Bile | An alkaline secretion from liver that helps break down fats into small droplets |
| Binocular vision | The placement of the eyes such that both see the same wide area but from slightly different angles |
| Binomial | The two-part Latinized name of a species, consisting of genus and species names |
| Blastocyst | A hollow ball of cells that develop from the fertilized ovum |
| Blind spot | The area of retina at end of optic nerve where there are no receptor cells |
| Blood | The fluid that circulates in the blood vessels |
| Blood pressure | The pressure of blood on the walls of the blood vessels |
| Body cavity | A space within the body that contains various organs |
| Bowman’s capsule | The double walled globe at proximal end of nephron. Encloses glomerulus |
| Brain stem | The part of the brain just above the spinal cord. Contains the medulla oblongata |
| Breed | A race or variety |
| Bronchiole | A branch of the bronchi in the respiratory system |
| Bronchus | One of the large branches of the trachea |
| Buccal | To do with the mouth |