Biology Circulation

Front 1

alveolus

Back 1

One of the dead-end, multilobed air sacs that constitute the gas exchange surface of the lungs.

Front 2

arteriole

Back 2

A vessel that conveys blood between an artery and a capillary bed.

Front 3

artery

Back 3

A vessel that carries blood away from the heart to organs throughout the body.

Front 4

atherosclerosis

Back 4

A cardiovascular disease in which growths called plaques develop on the inner walls of the arteries, narrowing their inner diameters.

Front 5

atrioventricular (AV) node

Back 5

A region of specialized muscle tissue between the right atrium and right ventricle. It generates electrical impulses that primarily cause the ventricles to contract.

Front 6

atrioventricular valve

Back 6

A valve in the heart between each atrium and ventricle that prevents a backflow of blood when the ventricles contract.

Front 7

atrium

Back 7

A chamber that receives blood returning to the vertebrate heart.

Front 8

blood

Back 8

A type of connective tissue with a fluid matrix called plasma in which blood cells are suspended.

Front 9

blood pressure

Back 9

The hydrostatic force that blood exerts against the wall of a vessel.

Front 10

blood vessels

Back 10

A set of tubes through which the blood moves through the body.

Front 11

Bohr shift

Back 11

A lowering of the affinity of hemoglobin for oxygen, caused by a drop in pH; facilitates the release of oxygen from hemoglobin in the vicinity of active tissues.

Front 12

breathing

Back 12

The process involving alternate inhalation and exhalation of air that ventilates the lungs.

Front 13

breathing control center

Back 13

A brain center that directs the activity of organs involved in breathing.

Front 14

bronchiole

Back 14

One of the fine branches of the bronchus that transport air to alveoli.

Front 15

bronchus

Back 15

One of a pair of breathing tubes that branch from the trachea into the lungs.

Front 16

capillary

Back 16

A microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between the blood and interstitial fluid.

Front 17

capillary bed

Back 17

A network of capillaries that infiltrate every organ and tissue in the body.

Front 18

cardiac cycle

Back 18

The alternating contractions and relaxations of the heart.

Front 19

cardiac output

Back 19

The volume of blood pumped per minute by the left ventricle of the heart.

Front 20

cardiovascular disease

Back 20

Diseases of the heart and blood vessels.

Front 21

cardiovascular system

Back 21

A closed circulatory system with a heart and branching network of arteries, capillaries, and veins. The system is characteristic of vertebrates.

Front 22

closed circulatory system

Back 22

A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid.

Front 23

countercurrent exchange

Back 23

The opposite flow of adjacent fluids that maximizes transfer rates; for example, blood in the gills flows in the opposite direction in which water passes over the gills, maximizing oxygen uptake and carbon dioxide loss.

Front 24

diaphragm

Back 24

A sheet of muscle that forms the bottom wall of the thoracic cavity in mammals; active in ventilating the lungs.

Front 25

diastole

Back 25

The stage of the heart cycle in which the heart muscle is relaxed, allowing the chambers to fill with blood.

Front 26

diastolic pressure

Back 26

Blood pressure that remains between heart contractions.

Front 27

dissociation curve

Back 27

A chart showing the relative amounts of oxygen bound to hemoglobin when the pigment is exposed to solutions varying in their partial pressure of dissolved oxygen.

Front 28

double circulation

Back 28

A circulation scheme with separate pulmonary and systemic circuits, which ensures vigorous blood flow to all organs.

Front 29

electrocardiogram (ECG or EKG)

Back 29

A record of the electrical impulses that travel through cardiac muscle during the heart cycle.

Front 30

endothelium

Back 30

The innermost, simple squamous layer of cells lining the blood vessels; the only constituent structure of capillaries.

Front 31

erythrocyte

Back 31

A red blood cell; contains hemoglobin, which functions in transporting oxygen in the circulatory system.

Front 32

erythropoietin

Back 32

A hormone produced in the kidney when tissues of the body do not receive enough oxygen. This hormone stimulates the production of erythrocytes.

Front 33

fibrin

Back 33

The activated form of the blood-clotting protein fibrinogen, which aggregates into threads that form the fabric of the clot.

Front 34

fibrinogen

Back 34

The inactive form of the plasma protein that is converted to the active form fibrin, which aggregates into threads that form the framework of a blood clot.

Front 35

gas exchange

Back 35

The uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment.

Front 36

gill

Back 36

A localized extension of the body surface of many aquatic animals, specialized for gas exchange.

Front 37

gill circulation

Back 37

The flow of blood through gills.

Front 38

heart

Back 38

A muscular pump that uses metabolic energy to elevate hydrostatic pressure of the blood. Blood then flows down a pressure gradient through blood vessels that eventually return blood to the heart.

Front 39

heart attack

Back 39

The death of cardiac muscle tissue resulting from prolonged blockage of one or more coronary arteries.

Front 40

heart murmur

Back 40

A hissing sound that occurs when blood squirts backward through a leaky valve in the heart.

Front 41

heart rate

Back 41

The rate of heart contraction.

Front 42

hemocyanin

Back 42

A type of respiratory pigment that uses copper as its oxygen-binding component. Hemocyanin is found in the hemolymph of arthropods and many molluscs.

Front 43

hemoglobin

Back 43

An iron-containing protein in red blood cells that reversibly binds oxygen.

Front 44

hemolymph

Back 44

In invertebrates with an open circulatory system, the body fluid that bathes tissues.

Front 45

high-density lipoprotein (HDL)

Back 45

A cholesterol-carrying particle in the blood, made up of cholesterol and other lipids surrounded by a single layer of phospholipids in which proteins are embedded. An HDL particle carries less cholesterol than a related lipoprotein, LDL, and may be correlated with a decreased risk of blood vessel blockage.

Front 46

hypertension

Back 46

Chronically high blood pressure within the arteries.

Front 47

larynx

Back 47

The voice box, containing the vocal cords.

Front 48

leukocyte

Back 48

A white blood cell; typically functions in immunity, such as phagocytosis or antibody production.

Front 49

low-density lipoprotein (LDL)

Back 49

A cholesterol-carrying particle in the blood, made up of cholesterol and other lipids surrounded by a single layer of phospholipids in which proteins are embedded. An LDL particle carries more cholesterol than a related lipoprotein, HDL, and high LDL levels in the blood correlate with a tendency to develop blocked blood vessels and heart disease.

Front 50

lung

Back 50

An invaginated respiratory surface of terrestrial vertebrates, land snails, and spiders that connects to the atmosphere by narrow tubes.

Front 51

lymph

Back 51

The colorless fluid, derived from interstitial fluid, in the lymphatic system of vertebrate animals.

Front 52

lymph node

Back 52

Organ located along a lymph vessel. Lymph nodes filter lymph and help attack viruses and bacteria.

Front 53

lymphatic system

Back 53

A system of vessels and lymph nodes, separate from the circulatory system, that returns fluid, proteins, and cells to the blood.

Front 54

myogenic heart

Back 54

A type of heart, such as in vertebrate animals, in which the pacemaker is made up of specialized muscle tissues and located within the heart itself.

Front 55

myoglobin

Back 55

An oxygen-storing, pigmented protein in muscle cells.

Front 56

negative pressure breathing

Back 56

A breathing system in which air is pulled into the lungs.

Front 57

neurogenic heart

Back 57

A type of heart, such as in insects, in which the pacemakers originate in motor nerves arising from outside the heart.

Front 58

open circulatory system

Back 58

A circulatory system in which fluid called hemolymph bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid.

Front 59

pacemaker

Back 59

A specialized region of the right atrium of the mammalian heart that sets the rate of contraction; also called the sinoatrial (SA) node.

Front 60

parabronchus (plural, parabronchi)

Back 60

A site of gas exchange in bird lungs. Parabronchi allow air to flow past the respiratory surface in just one direction.

Front 61

partial pressure

Back 61

A measure of the concentration of one gas in a mixture of gases; the pressure exerted by a particular gas in a mixture of gases (for instance, the pressure exerted by oxygen in air).

Front 62

peripheral resistance

Back 62

The impedance of blood flow by the arterioles.

Front 63

plasma

Back 63

The liquid matrix of blood in which the cells are suspended.

Front 64

platelet

Back 64

A small enucleated blood cell important in blood clotting; derived from large cells in the bone marrow.

Front 65

positive pressure breathing

Back 65

A breathing system in which air is forced into the lungs.

Front 66

pulmocutaneous circuit

Back 66

The route of circulation that directs blood to the skin and lungs.

Front 67

pulse

Back 67

The rhythmic stretching of the arteries caused by the pressure of blood forced through the arteries by contractions of the ventricles during systole.

Front 68

red blood cell

Back 68

A blood cell containing hemoglobin, which transports O2; also called an erythrocyte

Front 69

residual volume

Back 69

The amount of air that remains in the lungs after forcefully exhaling.

Front 70

respiratory medium

Back 70

The source of oxygen. It is typically air for terrestrial animals and water for aquatic organisms.

Front 71

respiratory pigment

Back 71

A special protein that transports most of the oxygen in blood.

Front 72

respiratory surface

Back 72

The part of an animal where gases are exchanged with the environment.

Front 73

semilunar valve

Back 73

A valve located at the two exits of the heart, where the aorta leaves the left ventricle and the pulmonary artery leaves the right ventricle.

Front 74

sinoatrial (SA) node

Back 74

A region of the heart composed of specialized muscle tissue that sets the rate and timing at which all cardiac muscle cells contract.

Front 75

sinus

Back 75

Any of the spaces surrounding the organs of the body in animals with open circulatory systems.

Front 76

stem cell

Back 76

Any relatively unspecialized cell that can divide during a single division into one identical daughter cell and one more specialized daughter cell, which can undergo further differentiation.

Front 77

stroke

Back 77

The death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head.

Front 78

stroke volume

Back 78

The amount of blood pumped by the left ventricle in each contraction.

Front 79

systemic circuit

Back 79

The branch of the circulatory system that supplies all body organs and then returns oxygen-poor blood to the right atrium via the veins.

Front 80

systemic circulation

Back 80

Movement of blood through the systemic circuit.

Front 81

systole

Back 81

The stage of the heart cycle in which the heart muscle contracts and the chambers pump blood.

Front 82

systolic pressure

Back 82

Blood pressure in the arteries during contraction of the ventricles.

Front 83

thrombus

Back 83

A clump of platelets and fibrin that blocks the flow of blood through a blood vessel.

Front 84

tidal volume

Back 84

The volume of air an animal inhales and exhales with each breath.

Front 85

trachea

Back 85

The windpipe; that portion of the respiratory tube that has C-shaped cartilagenous rings and passes from the larynx to two bronchi.

Front 86

tracheal system

Back 86

A gas exchange system of branched, chitin-lined tubes that infiltrate the body and carry oxygen directly to cells in insects.

Front 87

vein

Back 87

(1) In animals, a vessel that returns blood to the heart. (2) In plants, a vascular bundle in a leaf.

Front 88

ventilation

Back 88

Any method of increasing contact between the respiratory medium and the respiratory surface.

Front 89

ventricle

Back 89

(1) A heart chamber that pumps blood out of a heart. (2) A space in the vertebrate brain, filled with cerebrospinal fluid.

Front 90

venule

Back 90

A vessel that conveys blood between a capillary bed and a vein.

Front 91

vital capacity

Back 91

The maximum volume of air that a respiratory system can inhale and exhale.

Front 92

vocal cord

Back 92

One of a pair of string-like tissues in the larynx. Air rushing past the tensed vocal cords makes them vibrate, producing sounds.

Front 93

white blood cell

Back 93

A blood cell that functions in defending the body against infections and cancer cells; also called a leukocyte.