PF VET113 / VET114 Anatomy & Physiology Terms

antrum

(1) The fluid filled space within an ovarian follicle. ( 2) The muscular part of the stomach that is responsible for grinding of food; located between the body of the stomach and the pylorus.

ampulla of the vas deferens

An enlargement of the vas deferens just before it enters the urethra. It is present in some species and absent in others.

amyloid

An excessive amount of a waxlike, proteinaceous substance in the body's tissue.

alula

Bone in birds that originates from the wrist and is comparable to a first finger; carries feathers that aid in steering.

anticodon

The triplet pair of nucleotides in tRNA that correspond to the triplet bases or codons of mRNA.

anisodactyly

Toe position in which three toes face forward and once faces the rear.

adrenal glands

Two endocrine glands located near the cranial poles of the kidneys. Each consists of an outer cortex and an inner medulla.

antiport system

When two separate materials are moved across the plasma membrane in opposite directions at the same time.

agranulocytes

White blood cells without cytoplasmic granules. The agranulocytes are the monocytes and the lymphocytes; also known as nongranulocytes. air sacs Nine thin, transparent membranes that are connected to the primary and secondary bronchi and act as reservoirs for air entering and leaving the lungs. albumin Protein manufactured by the liver that plays an important role in maintaining the osmotic fl uid balance between capillaries ( blood) and tissues; a lack of albumin results in movement of fl uid from the capillaries into the tissues, producing edema and fl uid accumulation in body cavities.

amorphous

Having no defined shape.

anucleated

Having no nuclei. anuria Condition in which no urine is being passed from the body.

androgens

Hormones that promote the development of male characteristics; male sex hormones. The principal androgen is testosterone. anemia Decreased oxygen carrying capacity of the blood caused by insuffi cient numbers of red blood cells, decreased hemoglobin concentration, or a combination of both of these conditions.

A bands

Large, dark bands in a skeletal muscle fiber that alternate with lighter I bands to give a striped appearance to skeletal muscle fibers under a microscope. The A bands are composed of thick fi laments of the contractile protein myosin.

alopecia

Loss of hair.

aorta

Major artery of the systemic circulation that receives blood from the left ventricle.

alveoli ( singular, alveolus)

Microscopic, thin walled sacs surrounded by networks of capillaries. The interface between the wall of the alveoli and the wall of the capillary is where the actual exchange of gases takes place in the lungs.

anconeal process

A beak shaped process at the proximal end of the trochlear notch of the ulna. When it fails to unite with the ulna, an ununited anconeal process can cause the elbow joint to become unstable, leading to lameness.

anaerobic

A biochemical pathway that can function without oxygen. The term also may be used to describe microbes that can live in the absence of oxygen.

absorptive cell

A cell commonly found in the small intestine that can absorb nutrients from the luminal surface via phagocytosis and pinocytosis. Absorptive cells have large surface areas as a result of the presence of microvilli. The expanded surface area increases the absorptive capability of the cell.

anterior

A directional term meaning toward the front ( of a human body).

acromegaly

A form of giantism that results from an excess of growth hormone (GH).

apocrine gland

A gland whose secretions contain some of its cellular material. Part of the secretory cell is destroyed and must regenerate before the cell can secrete again. Examples of these glands are mammary glands and some sweat glands.

adenosine triphosphate ( ATP)

A high energy molecule produced in the mitochondria of cells. It is a nucleotide that contains three phosphoric acid groups. When a phosphate group is split off of an ATP molecule to produce ADP, energy is released that powers the sliding of the actin and myosin fi laments in muscle over each other. When the phosphate group is reattached, which requires another energy source, ADP is converted back to ATP and the molecule is ready to provide energy again. The more active a cell or body part is, the more ATP it will have produced and stored. For instance, muscles have a great deal of stored ATP, whereas fat has relatively little.

antidiuretic hormone ( ADH)

A hormone released by the posterior pituitary. It facilitates water conservation in the body by promoting water reabsorption from urine in the collecting ducts. Low levels of ADH cause diabetes insipidus, a condition that results in excessive water loss from the body through increased urine volume.

aldosterone

A mineralocorticoid hormone secreted by the cortex of the adrenal gland. It stimulates the kidney to conserve sodium ions and water and to eliminate potassium and hydrogen ions.

anions

A negatively charged atom or molecule; a negatively charged ion.

adenosine monophosphate ( AMP)

A nucleotide that contains one phosphoric acid group. AMP is produced by the hydrolysis of one high energy phosphate bond of ADP. This releases energy that can be used by cells or phosphorylated back into ADP.

actin

A protein that composes microfi laments. It is found in the cytoskeleton, in myofi brils of muscle fibers, and in spindle fibers during cell division.

aortic valve

A semilunar valve; it separates the left ventricle and the aorta during diastole.

anaphylaxis

A severe, potentially life threatening, allergic response. anapsid skulls Skulls of primitive reptiles ( all extinct except turtles) that have no openings in the temporal region.

amphiarthrosis

A slightly movable cartilaginous joint, such as the pelvic symphysis.

adipose connective tissue

A subclass of connective tissue proper, adipose connective tissue is a vascularized type of connective tissue whose general functions are to protect, insulate, and provide a major source of energy to the body. Adipose connective tissue can occur as either brown or white adipose tissue. White adipose tissue, found commonly throughout the body, is a storage area for lipids. These lipids may be used for the production of energy, or ATP. Brown adipose tissue, found in neonate and hibernating species, has its lipids converted to heat.

anticoagulant

A substance that prevents blood from clotting when it is added to the blood.

adipocyte

A type of fixed cell in the connective tissue that stores fat ( lipids) in its cytoplasm. The nucleus and other organelles are pushed to the periphery of the cell.

active immunity

Activation of the immune system by either administration of a vaccine that contains a modified antigen or exposure to the antigen ( e. g., by disease).

adenosine diphosphate (ADP)

Adenosine diphosphate is the " discharged" form of adenosine triphosphate ( ATP). It is a nucleotide that contains two phosphoric acid groups. When a phosphate group is split off of an ATP molecule to produce ADP, energy is released that powers the sliding of the actin and myosin fi laments in muscle over each other. When the phosphate group is reattached, which requires another energy source, ADP is converted back to ATP, and the molecule is ready to provide energy again.

alimentary canal

Also called the digestive tract, this encompasses all of the parts of the digestive system that transport food from the mouth to the anus: mouth, esophagus, stomach, small and large intestines, and anus.

amoeboid motion

Amoeba like movement accomplished by the extension of pseudopodia to create a streaming movement of cytoplasm.

anaerobic glycolysis

An alternative expression for glycolysis, referring to the fact that the reaction does not require oxygen.

ampulla

An enlargement in each semicircular canal that contains the receptor structure ( the crista).

alpha cells

Cells in the pancreas that produce glucagon.

antigens

Cells or organisms that are "not self." An antigen also can be a structure on a cell membrane that the body recognizes as foreign. The presence of an antigen initiates an immune response in a healthy animal.

alveolar sacs

Clusters of alveoli at the ends of the alveolar ducts. The alveoli are arranged like bunches of grapes.

anesthesia

Complete loss of sensation.

analgesia

Decreased perception of pain.

amylase

Enzyme produced by the pancreas and, in some species, the saliva; attacks starch and breaks it into disaccharides ( two sugar molecules).

apocrine sweat glands

Exocrine glands that secrete substances into the hair follicle, rather than directly to the skin surface.

adipose

Fat.

afferent nerve

Nerve that carries im pulses toward the central nervous system.

adrenergic neurons

Neurons that secrete catecholamines ( e. g., norepinephrine) as their neurotransmitter. adrenocorticotropic hormone ( ACTH) A hormone secreted by the anterior portion of the pituitary gland, which in turn activates the cortex of the adrenal gland. The adrenal cortex then releasesits own hormones. ACTH is vital to the normal function and development of the adrenal cortex.

anaerobic metabolism

Non-oxygen dependent metabolism. The type of metabolism in muscle that occurs when the need for energy to produce muscular activity exceeds the available oxygen supply. Anaerobic metabolism is not as efficient as aerobic metabolism and results in the formation of lactic acid as a byproduct. Lactic acid can cause discomfort in muscle tissue and requires oxygen to be converted back to glucose.

adenine (A)

One of the nucleotides present in both DNA and RNA. It is a purine base that corresponds to RNA's uracil and DNA's thymine.

actin filaments

One of the two contractile proteins of muscle (the other is myosin) that slide over each other to produce the shortening of the muscle cell that we refer to as muscle contraction.

aerobic metabolism

Oxygen consuming metabolism. The type of metabolism in muscle in which the supply of available oxygen is suffi cient to keep up with the energy needs of the muscle fi bers. Aerobic metabolism extracts the maximum amount of energy from glucose molecules.

amniotic sac

Part of the placenta. It is the fluid filled sac that immediately surrounds the developing fetus.

allantois

Part of the placenta. It is the membrane that forms the allantoic sac.

amnion

Part of the placenta. It is the membrane that forms the fluid filled amniotic sac.

anal sacs

Perianal sacs, containing apocrine and sebaceous glands, that are located at the 5 o'clock and 7 o'clock positions relative to the anus. The sacs reside between the internal and external sphincter of carnivores and produce a strong smelling fl uid when expressed; they are important for fecal territorial marking and are expressed during fearful episodes.

agglutination

Precipitation or clumping of antigen antibody complexes; one of the methods by which the immune system neutralizes antigens.

aminopeptidase

Protease secreted in an inactive form from the pancreas and activated by trypsin.

antibodies

Proteins produced by plasma cells ( transformed B lymphocytes) in response to the presence of an antigen. A specifi c serum antibody is generated for a specifi c antigen.

alpha1 adrenergic receptors

Receptors associated with the sympathetic nervous system response; these receptors, when stimulated by catecholamines, cause vasoconstriction.

aglyphous

Referring to having solid teeth, without a groove for venom ( used to classify snake groups).

alveolar gland

Secretory unit of exocrine glands that are saclike in form; also called acinar gland.

adipose cells

See adipocyte.

ACTH

See adrenocorticotropic hormone.

antagonist

Something that opposes the action of something else. An antagonist muscle or muscle group directly opposes the action of a " prime mover" muscle or muscle group that is directly producing a desired movement.

acids

Substances that dissolve in water to yield hydrogen ions and produce a solution with a pH less than 7.

antebrachium

The " forearm" region of the thoracic limb.

abomasum

The "true stomach" of the ruminant; secretes acids, mixes and contracts ingesta, and moves liquid chyme into the small intestine.

anterior pituitary gland

The adenohypophysis; the rostral portion of the pituitary gland that produces seven hormones, many of which infl uence other endocrine glands.

alkaline

The adjective that describes substances with a pH above 7 ( basic). Basic or alkaline solutions have fewer hydrogen ions or more hydroxide ions than pure water. all or nothing principle The principle that an individual muscle fi ber either contracts completely or does not contract at all. allantoic sac Part of the placenta. It is a fl uid fi lled sac formed by the allantois that surrounds the amniotic sac.

angle

The angle of the hoof wall as viewed from a lateral aspect when the foot is fl at on the ground.

amino acid

The basic building block of peptides and proteins; those organic compounds, numbering around 80, that are made up of an amino group ( NH2) and a carboxyl group ( COOH). Amino acids make up proteins when joined together in peptide bonds. They are naturally occurring in all plants and animals.

acrosome

The caplike structure that partially covers the heads of spermatozoa. It contains digestive enzymes that are activated when the cells enter the female reproductive tract. They help the cell penetrate through the layers around the ovum to fertilize it.

aerobic respiration

The cell function that produces chemical energy with the use of oxygen.

anaerobic respiration

The cell function that produces energy chemically with the use of free oxygen. anagen phase The active phase of hair growth.

alpha helix

The coiled structure in a complex protein composed of hydrogen bonds and amino acids. altricial Chicks that are hatched with their eyes closed and their skins bare and that are immobile.

active site

The specific area on an enzyme that connects with a substrate to cause a chemical reaction.

apex ( of a tooth)

The tip of the tooth root where the blood and nerve supply enter the tooth; the uppermost point of a structure.

anatomy

The study of the form and structure of an animal body and its parts. Through anatomy we can describe where things are located in or on the animal body and what they look like.

anticlinal vertebra

The thoracic vertebra whose spinous process projects straight up dorsally in contrast to the caudally inclined spinous processes cranial to it and the cranially inclined spinous processes caudal to it. It acts as a landmark on radiographs of the thoracolumbar region, particularly in dogs, in which it is the eleventh thoracic vertebra.

acetylcholinesterase

The enzyme that breaks down acetylcholine.

accommodation

The focusing of the lens of the eye to allow close up and faraway vision. It is accomplished by the muscles of the ciliary body that apply or relieve tension on the suspensory ligaments that attach it to the lens.

anabolism

The form of metabolism by which cells build complex compounds from simpler ones; the opposite of catabolism. The process by which the cell uses energy to manufacture large molecules from smaller ones; these molecules are used to maintain the cell and carry out metabolic processes.

adrenal medulla

The inner portion of the adrenal gland that produces the hormones epinephrine and norepinephrine.

abduction

The joint movement whereby an extremity is moved away from the median plane.

adduction

The joint movement whereby an extremity is moved toward the median plane.

activation energy

The minimum energy required for a chemical reaction to occur.

afterbirth

The name given to the placenta at parturition because it is delivered after the newborn.

adrenal cortex

The outer portion of the adrenal gland that produces glucocorticoid, mineralocorticoid, and sex hormones.

anestrus

The period when the ovary "shuts down" between the estrous cycles or breeding seasons of some animal species.

anaphase

The phase of mitosis when the daughter chromosomes begin to migrate to their respective centrioles, away from the center of the dividing cell.

anterior chamber

The portion of the aqueous compartment of the eye in front of ( rostral to) the iris.

adult hemoglobin

The primary type of hemoglobin found in the red blood cells of animals beginning a couple of weeks to a couple of months after birth.

active transport

The process that moves ions or molecules across the cell membrane and against the concentration gradient; requires energy.

apical surface

The side of an epithelial cell that faces in toward the body cavity.

alveolar ducts

The smallest air passageways in the lungs. The alveolar ducts carry air to the alveolar sacs.

afferent glomerular arterioles

The smallest arteriole branches that carry blood into the glomerulus for fi ltration.

acetabulum

The socket portion of the ball and socket hip joint. It is formed at the junction of the ilium, ischium, and pubic bones of the pelvis. acetylcholine A neurotransmitter associated with somatic nerves and with parasympathetic nervous system effects even though it is used in the preganglionic neuron in both the sympathetic and parasympathetic nervous systems; has a stimulatory effect on the gastrointestinal tract, it increases secretions and muscle contractions in the esophagus, stomach, ruminant forestomachs, intestine, and colon.