The Human Body Flashcards
abduction
The action of moving a limb farther from the midline of the body. In muscle names, abductor indicates a muscle that has this action.
acetylcholine
A major neurotransmitter in the body, conveying signals from nerves to muscles as well as between many nerves.
action potential
The electrical nerve impulse that travels along the axon of a nerve cell (neuron).
adduction
The action of moving a limb closer to the midline of the body. In muscle names, adductor indicates a muscle that has this action.
adrenal glands
Also called suprarenal glands. A pair of glands found one on top of each kidney. Each gland consists of an outer adrenal cortex, which secretes corticosteroid hormones, and an inner adrenal medulla, which secretes epinephrine.
afferent
In blood vessels, carrying blood toward an organ, and in nerves, conducting impulses toward the central nervous system.
allergy
An unnecessary and sometimes dangerous immune response that targets otherwise non-threatening foreign material, such as plant pollen.
alveolus (pl. alveoli)
A small cavity; specifically, one of the millions of tiny air sacs in the lungs where exchange of gases with the blood takes place; also, the technical term for a tooth socket.
amino acid
Proteins are made from up to 20 different types of these small, nitrogen-containing molecules; amino acids also play various other roles in the body.
amnion
The membrane that encloses the developing fetus within the uterus (womb). The fluid inside it (amniotic fluid) helps cushion and protect the baby.
anastomosis
An interconnection between two otherwise separate blood vessels (e.g. two arteries or an artery and a vein).
androgen
Steriod hormones that tend to promote male body and behavioral characteristics. They are secreted in larger amounts by men than women.
anemia
Damagingly low amounts of hemoglobin in the blood. Anemia can have many causes, from undetected bleeding to vitamin deficiencies.
angio-
A prefix relating to blood vessels.
angiography
In medical imaging: any technique for obtaining images of blood vessels in the living body.
antagonist
- A muscle that has the opposite action to another muscle.
2. A drug that interferes with the action of a hormone, neurotransmitter, etc. by binding to its receptor.
anterior
Towards the front of the body, when considered in a standing position. Anterior to means in front of.
antibiotic
Any of various chemical compounds, natural or synthetic, that destroy or prevent the growth of microorganisms (e.g. bacteria, yeasts, and fungi).
antibody
Defensive proteins produced by white blood cells that recognize and attach to particular “foreign” chemical components (antigens), such as the surface of an invading bacterium or virus. The body is able to produce thousands of different antibodies targeted at different invaders and toxins.
anticoagulant
A substance that prevents blood clotting.
antigen
Any particle or chemical substance that stimulates the immune system to produce antibodies against it.
aorta
The body’s largest artery, conveying blood pumped by the left ventricle of the heart. It extends to the lower abdomen, where it divides into the two common iliac arteries.
aponeurosis
A flattened, sheetlike tendon.
arteriole
A very small artery, leading into capillaries.
artery
A vessel carrying blood from the heart to the tissues and organs of the body. Arteries have thicker, more muscular walls than veins.
articulation
A joint, especially one allowing movement; also, a location within a joint where two bones meet in close proximity. A bone in a joint is said to articulate with the other bone(s) of the joint.
-ase
A suffix denoting an enzyme. For example, sucrase is an enzyme that breaks down sucrose.
ATP
Short for adenosine triphosphate, an enerty-storing molecule used by all living cells.
atrium (pl. atria)
Either of the two smaller chambers of the heart that receive blood from the veins and pass it on to the corresponding ventricle.
autoimmunity
A situation where the immune system attacks the body’s own tissues, often leading to disease.
autonomic nervous system
The part of the nervous system that controls non-conscious processes such as the activity of the body’s glands and the muscles of the gut. It is divided into the sympathetic nervous system, the roles of which include preparing the body for “fight or flight,” and the parasympathetic nervous system, which stimulates movement and secretions in the gut, produces erection of the penis during coitus, and empties bladder.
axon
A wirelike extension of a nerve cell (neuron) along which electrical signals are transmitted away from the cell.
bacterium (pl. bacteria)
Any member of a large group of single-celled living organisms, some o which are dangerous pathogens. Bacterial cells are much smaller than animal and plant cells, and lack nuclei.
basal ganglia
Groups of nerve cells deep in the cerebrum; consists of the caudate nucleus, putamen, globus pallidus, and subthalamic nucleus. Functions include controlling movement.
basophil
A type of leukocyte (white blood cell).
belly (of muscle)
The widest part of skeletal muscle, which bulges further when it contracts.
bilateral
Concerning or affecting both sides of the body or a body part.
bile
A yellow-green fluid produced by the liver, stored in the gallbladder, and discharged into the intestine via the bile duct. It contains excretory products together with bile acids that help with fat digestion.
biopsy
A sample taken from a living body to test for infection, cancerous growth, etc.; also the sampling process.
blood-brain barrier
The arrangements by which the brain is relatively protected from unwanted substances entering it from the blood. It includes capillaries that are less permeable to large molecules than elsewhere in the body.
brachial
Relating to the arm.
brain stem
The lowest part of the brain, leading down from the rest of the brain to the spinal cord. In descending order, it consists of the midbrain, pons, and medulla oblongata.
bronchus (pl. bronchi)
The air tubes branching from the trachea and leading into the lungs; right and left main bronchi enter each lung respectively and divide into lobar bronchi, and eventually into much smaller tubes called bronchioles.
cancer
an uncontrolled growth of cells with the potential to spread and form colonies elsewhere in the body. Cancer cells typically look different from their non-cancerous equivalents under the microscope. Cancers can arise in many different tissues.
cannula
A tube inserted into any part of the body to drain fluid, introduce drugs, etc.
capillaries
The smallest blood vessels, with a wall only one cell thick, supplied by arterioles and draining into veins. Capillaries from networks, and are the sites where nutrients, gases, and waste products are exchanged between body tissue and blood.
carbohydrates
Naturally occurring chemical substances containing carbon, hydrogen, and oxygen atoms, e.g. sugars, starch, cellulose, and glycogen.
cardiac
Relating to the heart.
carpal
Relating to the wrist.
cartilage
A rubbery or tough supportive tissue (colloquially “gristle”) found in various forms around the body.
catheter
A tube inserted into the body, for example, a urinary catheter may be inserted into the urethra to drain urine from the bladder.
cecum
The first part of the large intestine.
cell
A tine structure containing genes, a surrounding fluid (cytoplasm) that carries out chemical reactions, organells, and an enclosing membrane.
central nervous system
The brain and spinal cord, as distinct from the nerves that run through the rest of the body (the peripheral nervous system).
cerebellum
An anatomically distinct region of the brain below the back of the cerebrum, responsible for coordinating the details of complex bodily movements, and managing balance and posture.
cerebrospinal fluid
The clear fluid that fills the ventricles of the brain and surrounds the brain and spinal cord, helping to provide a constant environment and acting as a shock absorber.
cerebrum
The larges part of the brain and the locus of most “higher” mental activities. It is divided into two halves called cerebral hemispheres.
cervical
- Relating to the neck.
2. Relating to the cervix (neck) of the uterus.
cervix
The narrow “neck” of the uterus, opening into the upper end of the vagina; widens during childbirth.
cholesterol
A natural chemical that is an essential constituent of the body’s cell membranes and is an intermediate molecule in the production of steroid hormones. It is a constituent of the plaques that cause the arteries to narrow in atherosclerosis.
chromosomes
The microscopic packages in the nucleus of a cell that contain genetic information in the form of DNA. Humans have 12 pairs of chromosomes, with a complete set present in nearly every cell of the body. Each chromosome consists of a single DNA molecule combined with various proteins.
cilium (pl. cilia)
A microscopic, beating, hairlike structure found in large numbers on the surfaces of some cells - for example in the air tubes of the lungs, where they help remove foreign particles.
circadian rhythm
An internal, daily body rhythm. It is kept accurate by reference to external light and dark.
clone
An identical copy or set of copies. Depending on the context, it can refer to: copied DNA molecules; a set of identical descendants of a given cell; or an animal bred artificially using genetic material from another adult individual.
cochlea
The complex spiral structure in the inner ear that translates sound vibrations in the fluid it contains into electrical impulses to be sent to the brain.
collagen
A tough, fibrous, structural protein that is widespread in the body (particularly in bone, cartilage, blood-vessel walls, and skin.)
colon
The main part of the large intestine; comprises the ascending, transverse, and descending colon.
commissure
A link between to structures, especially any of several nerve tracts in the brain and spinal cord that crosses the midline of the body.
compartment (as in anatomical grouping or area)
In the case of muscles, used to define an anatomically and functionally discrete group of muscles, e.g. flexor compartment of the forearm.
condyle
A rounded, knuckle-like projection on a bone that forms part of a joint.
connective tissue
Any tissue comprising cells embedded in an acellular matrix; includes cartilage, bone, tendon, ligament, and blood.
cornea
The tough, transparent, protective layer at the front of the eye; helps focus light on the retina.
coronal section
A real or imagined section down the body that divides it form side to side; it is perpendicular to a sagittal section.
corpus callosum
A large tract of nerve fibers (commissure) that links the brain’s two cerebral hemispheres.
cortex
The Latin word for bark, used for the outer parts of some organs, especially:
- The cerebral or cerebellar cortex - the surface layers of cells (the “gray matter”) of these parts of the brain.
- ) The adrenal cortex - the outer part of the adrenal glands.
corticosteroid
Any of several steroid hormones produced by the adrenal cortex. Examples include cortisone and cortisol (hydrocortisone), which have many effects on the body’s metabolism and also suppress inflammation. The mineral-regulating hormone aldosterone is also corticosteroid.
cranial
- Related to the cranium
2. Toward the head.
cranial nerves
Pairs of nerves that lead directly from the brain rather than from the spinal cord. They mainly supply structures in the head and neck.
cranium
Together with the mandible (jaw), forms the skull.
CFS
Short for cerebrospinal fluid
CT
Short for computed tomography, a sophisticated x-ray technique that produces images in the form of “slices” through the patient’s body.
cutaneous
Relating to the skin.
cyst
A fluid-filled cavity in the body. Also, an old term for the bladder; hence cystitis.
deficiency disease
Any disease caused by a lack of an essential component of the diet, e.g. a protein or vitamin.
dendrite
A branchlike outgrowth of a nerve cell (neuron) that carries incoming electrical signals to that cell. A neuron usually has many dendrites.
depressor
Term used in names of several muscles that act to pull down, e.g. depressor anguli oris (pulls down the angle of the mouth).
diabetes
Short for diabetes mellitus, a condition involving high levels of glucose (sugar) in the blood, caused by insufficient production of the hormone insulin.
diaphragm
A sheet of muscle that separates the thorax from the abdomen. When relaxed it is domed upward; it flattens when contracted, to increase thoracic volume and draw air into the lungs. It is the most important muscle used in breathing.
diastole
The phase of the cardiac cycle when the heart relaxes and the ventricles refill with blood.
diffusion
The net movement of molecules in a fluid (gas or liquid) from regions of high to lower concentration.
dilated
Opened or stretched wider.
distal
Relatively farther away from the center of the body or from the point of origin.
DNA
Short for deoxyribonucleic acid, a very long molecule made up of small individual units or nucleotides, containing one of four bases. DNA is found in the chromosomes of living cells; the order of the bases “spells out” the genetic instructions of the animal.
dopamine
A neurotransmitter secreted mainly by groups of neurons whose cell bodies lie deep in the brain. Dopamine-producing regions are involved in the motivation, mood, control of movement, and other functions.
dorsal
Relating to the back or back surface of the body, or to the top of the brain; also, relating to the back (dorsum) of the hand or the upper surface of the foot.
duodenum
The first part of the small intestine, leading out of the stomach.
efferent
In the case of blood vessels, carrying blood away from an organ; in the case of nerves, conducting impulses away from the the central nervous system.
electrocardiography
Recording the electrical activity produced by the heart muscle, using electrodes applied to the patient’s skin.
embryo
The earliest stage of a developing unborn individual in the uterus, from fertilization until 8 weeks of gestation (after which is known as a fetus).
endocrine system
The system comprising glands that produce hormones.
endomentrium
The inner lining of the uterus.
endorphins
Neurotransmitters in the brain; their functions include diminishing the perception of pain.
endothelium
The cell layer that forms the inner lining of blood vessels.
enzyme
Any of a large variety of different molecules (most of which are proteins) that catalyze a particular chemical reaction in the body.)
eosinophil
A type of leukocyte (white blood cell).
epicondyle
A small bulge found on some bones near a joint, usually forming a site for muscle attachment.
epidermis
The outermost layer of skin, with a surface consisting of dead cells packed with the tough protein keratin.
epiglottis
A flexible flap of cartilage in the throat that helps cover the trachea (windpipe) during swallowing.
epinephrine
A hormone released by the adrenal glands in the response to stressful situations. It prepares the body for a “fight or flight” response by increasing heart rate, diverting blood flow to muscles, etc.
epithelium
Any tissue that forms the surface of an organ or structure. It may consist of a single layer of cells, or several layers.
erythrocyte
A red blood cell.
esophagus
The gullet: the tubular part of the alimentary canal between the pharynx and the stomach.
estrogens
Steroid hormones produced predominantly by theo ovary, and which regulate female sexual development and physiology. Artificial estrogens are used in oral contraceptives and hormone therapy.
extension
The movement that increases the angle of, or straightens, a joint. The name extensor indicates a muscle that has this action, e.g. extensor digitorum extends the fingers.
external
In anatomy: closer to the outer surface.
extracellular
Outside the cell; often used in reference to the fluid or matrix between cells of a connective tissue.
fallopian tube
Another name for the oviduct or uterine tube; two oviducts attach to the uterus, extending to the ovary on each side; the ovum travels down this tube after ovulation.
fascia (pl. fasciae)
Layers of fibrous tissue between and around muscles, vessels, and organs.
fertilization
The union of a sperm with an unfertilized egg (ovum), the first step in the creation of a new individual.
fetus
The unborn individual in the uterus, from 8 weeks after fertilization, when it begins to take on a recognizably human appearance.
flexion
The bending movement at a joint. The name flexor indicates a muscle that has this action, e.g. flexor carpi ulnaris bends the wrist.
follicle
A small cavity or saclike structure: e.g. the hair follicle from which a hair grows.
foramen
An opening, hole, or connecting passage.
fossa
A shallow depression or cavity.
frontal
Relating to or in the region of the forehead; frontal bone, the skull bone of the forehead; frontal lobe, the foremost lobe of each cerebral hemisphere, lying behind the forehead.
gallbladder
The hollow organ into which bile (formerly known as gall) secreted by the liver is stored and concentrated before being transferred to the intestine.
gamete
A sperm or an ovum (egg0. Gametes contain just one set of 23 chromosomes, whereas normal body cells have two sets (46 chromosomes). When sperm and egg combine during fertilization, the two-set condition is restored.
ganglion
- A concentration of nerve cell bodies, especially one outside of the central nervous system.
- A swelling on a tendon sheath.
gastric
Relating to the stomach.
gene
A length of a DNA molecule that contains a particular genetic instruction. Many genes are blueprints for making particular protein molecules, while some have a role in controlling other genes. Among them, the thousands of different genes in the body provide the instructions for a fertilized egg to grow into an adult, and for all essential activities of the body to be carried out. Nearly every cell in the body contains an identical sets of genes, although different genes are “switched on” in different cells.
genome
The complete set of genes found in a human or other living species. The human genome is thought to contain about 20,000-25,000 different genes.
genotype
The genetic makeup of a particular individual. Idential twins, for example, have the same genotype because they share identical versions of all their genes.
gland
A structure in teh body, the main purpose of which is to secrete particular chemical substances or fluids. Glands are either exocrine, releasing their secretions through a duct onto an external or internal surface, such as the salivary glands, or endocrine, releasing hormones into the bloodstream.
glial cells
Cells in the nervous system that are not neurons but play various supportive and protective roles withing the nervous system.
globulin
A general name for various proteins found in the blood that have roughly spherical shape.
glomerulus
A cluster of nerve endings or capillaries, such as the tiny knot of capillaries enclosed in the cuplike Bowman’s capsule of a nephron.
gloss-, glosso-
Prefixes relating to the tongue.
glucagon
A hormone produced by the pancreatic islets that increases glucose levels in the blood; its effect is opposite to that of insulin.
glucose
A simple sugar that is the main energy source used by the body’s cells.
glycogen
A carbohydrate made up of long, branched chains of connected glucose molecules. The body stores glucose in the form of glycogen, especially in the muscles and liver; also called animal starch.
gonad
An organ that produces sex cells (gametes) - I.e. an ovary or a testix. A gonadotropin is a hormone that specifically affects the gonads.
gyrus (pl. gyri)
One of the folds on the outer surface of the brain.