Chapter 34 – Circulation and Gas Exchange: Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering the key terms from Chapter 34 on circulation and gas exchange.

diffusion

Random thermal motion of particles that leads to net movement from regions of higher to lower concentration down a gradient.

gastrovascular cavity

Central cavity with a single opening in some animals that functions in digestion and nutrient distribution.

heart

Muscular pump that raises hydrostatic pressure of circulatory fluid, driving it through the body.

open circulatory system

Circulatory system in which hemolymph bathes tissues directly without distinction from interstitial fluid.

hemolymph

Body fluid that bathes tissues in invertebrates with an open circulatory system.

closed circulatory system

Circulatory system in which blood is confined to vessels and kept separate from interstitial fluid.

blood

Connective tissue whose fluid matrix (plasma) suspends red cells, white cells, and platelets.

cardiovascular system

Closed circulatory system of vertebrates with a heart plus arteries, capillaries, and veins.

artery

Vessel that carries blood away from the heart to organs.

capillaries

Microscopic vessels of single-cell endothelium allowing exchange between blood and interstitial fluid.

veins

Vessels that carry blood toward the heart.

atrium

Heart chamber that receives blood from veins and transfers it to a ventricle.

ventricle

Heart chamber that pumps blood out of the heart.

single circulation

Circulatory pattern with one pump and circuit; blood passes from gas-exchange sites to body before returning to heart.

double circulation

Circulatory pattern with separate pulmonary and systemic circuits; blood returns to heart after each circuit.

cardiac cycle

Alternating contractions and relaxations of the heart.

systole

Phase of the cardiac cycle when a heart chamber contracts and pumps blood.

diastole

Phase of the cardiac cycle when a heart chamber relaxes and fills with blood.

atrioventricular (AV) valve

Valve between each atrium and ventricle that prevents back-flow during ventricular contraction.

semilunar valves

Valves at heart exits where aorta leaves left ventricle and pulmonary artery leaves right ventricle.

sinoatrial (SA) node

Pacemaker region in right atrium that sets rate and timing of cardiac muscle contraction.

electrocardiogram (ECG or EKG)

Record of electrical impulses traveling through heart muscle during the cardiac cycle.

atrioventricular (AV) node

Specialized tissue between atria where impulses are delayed ~0.1 s before spreading to ventricles.

endothelium

Simple squamous cell layer lining the lumen of blood vessels.

vasoconstriction

Decrease in blood-vessel diameter due to smooth-muscle contraction.

vasodilation

Increase in blood-vessel diameter due to smooth-muscle relaxation.

pulse

Rhythmic bulging of artery walls with each heartbeat.

lymphatic system

Vessels and nodes, separate from circulatory system, that return fluid, proteins, and cells to blood.

lymph

Colorless fluid derived from interstitial fluid within the lymphatic system.

lymph node

Organ along lymph vessels that filters lymph and houses cells attacking pathogens.

plasma

Liquid matrix of blood in which blood cells are suspended.

platelets

Pinched-off cytoplasmic fragments important in blood clotting.

stem cells

Relatively unspecialized cells that can self-renew or produce specialized progeny.

erythrocytes

Red blood cells containing hemoglobin for oxygen transport.

hemoglobin

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

sickle-cell disease

Recessive disorder where a β-globin mutation causes hemoglobin aggregation and misshapen red cells.

leukocytes

White blood cells that function in fighting infections.

thrombus

Fibrin-containing clot forming inside a vessel, blocking blood flow.

atherosclerosis

Disease in which fatty plaques develop in arterial walls, hardening and obstructing arteries.

heart attack

Damage or death of cardiac muscle from prolonged blockage of coronary arteries.

stroke

Death of brain nervous tissue from rupture or blockage of arteries in neck or head.

low-density lipoprotein (LDL)

Blood particle transporting cholesterol from liver for membrane incorporation.

high-density lipoprotein (HDL)

Blood particle that scavenges excess cholesterol.

hypertension

Condition in which blood pressure remains abnormally high.

gas exchange

Uptake of O₂ and discharge of CO₂ to/from the environment.

partial pressure

Pressure exerted by a particular gas within a mixture.

ventilation

Flow of air or water over a respiratory surface.

countercurrent exchange

Exchange between two fluids moving in opposite directions, maximizing diffusion (e.g., fish gills).

tracheal system

In insects, branched air-filled tubes delivering oxygen directly to cells.

lung

Infolded respiratory surface connected to atmosphere by narrow tubes in terrestrial animals.

larynx

Voice box portion of respiratory tract containing vocal cords.

trachea

Windpipe segment from larynx to bronchi.

bronchus

One of a pair of tubes branching from trachea into lungs.

alveolus

Dead-end air sac in mammalian lung where gas exchange occurs.

surfactant

Substance secreted by alveoli that reduces surface tension of alveolar fluid.

breathing

Ventilation of lungs through alternating inhalation and exhalation.

positive pressure breathing

Breathing mechanism that forces air into lungs.

negative pressure breathing

Breathing mechanism that pulls air into lungs.

diaphragm

Muscle sheet forming bottom of thoracic cavity; its contraction draws air into lungs.

tidal volume

Volume of air inhaled and exhaled with each normal breath.

vital capacity

Maximum volume of air that can be inhaled and exhaled with a single breath.

residual volume

Air remaining in lungs after forceful exhalation.

respiratory pigment

Protein that transports oxygen in blood or hemolymph.

Bohr shift

Drop in hemoglobin’s O₂ affinity caused by lowered pH, facilitating O₂ release near active tissues.

myoglobin

Oxygen-storing pigmented protein in muscle cells.