Circulation and Gas Exchange

A comprehensive set of vocabulary flashcards covering the mechanisms of circulation, blood components, respiratory surfaces, and gas exchange based on the Lecture 9 transcript.

Folic acid

A supplement added to grain products to reduce the risk of neural tube defects and improve human health.

Gastrovascular cavity

An elaborate chamber found in cnidarians, ctenophores, and flatworms that functions in both digestion and the distribution of substances throughout the body.

Open circulatory system

A system found in insects, other arthropods, and some mollusks where the circulatory fluid, hemolymph, bathes the organs directly.

Hemolymph

The circulatory fluid used in open circulatory systems.

Closed circulatory system

A system found in annelids, cephalopods, and vertebrates where blood is confined to vessels and is distinct from the interstitial fluid.

Arteries

Blood vessels that branch into arterioles and carry blood away from the heart to the capillaries.

Capillary beds

Networks of highly branched, thin-walled vessels that serve as sites for chemical exchange between the blood and interstitial fluid.

Venules

Small vessels that converge into veins to return blood from the capillaries to the heart.

Atria

The chambers of vertebrate hearts through which blood enters.

Ventricles

The chambers of vertebrate hearts through which blood is pumped out.

Single circulation

A circulatory arrangement in sharks, rays, and bony fishes featuring a two-chambered heart where blood passes through two capillary beds before returning to the heart.

Double circulation

An arrangement in amphibians, reptiles, birds, and mammals where oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart.

Pulmocutaneous circuit

A specific circuit in amphibians where oxygen-poor blood picks up oxygen through the lungs and skin.

Pulmonary circuit

The circuit in reptiles and mammals through which oxygen-poor blood flows to the lungs to pick up oxygen.

Systemic circuit

The circuit that delivers oxygen-rich blood to the body tissues.

Aorta

The large vessel through which the left ventricle pumps oxygen-rich blood to the systemic circuit, including the coronary arteries.

Cardiac cycle

The rhythmic cycle in which the heart contracts and relaxes.

Systole

The contraction or pumping phase of the cardiac cycle.

Diastole

The relaxation or filling phase of the cardiac cycle.

Atrioventricular (AV) valves

The valves that separate each atrium and ventricle to prevent the backflow of blood.

Semilunar valves

Valves that control blood flow to the aorta and the pulmonary artery.

Sinoatrial (SA) node

Also known as the pacemaker, this node sets the rate and timing at which cardiac muscle cells contract.

Endothelium

The smooth epithelial layer lining the central lumen of all blood vessels that minimizes resistance to blood flow.

Lymph

The fluid lost by capillaries that is returned to the blood by the lymphatic system.

Plasma

The liquid matrix of blood, consisting of water, dissolved ions (electrolytes), and proteins, which occupies about 55% of blood volume.

Erythrocytes

Red blood cells that contain hemoglobin and function primarily to transport $O_2$; in mammals, mature cells lack nuclei and mitochondria.

Hemoglobin

An iron-containing protein that binds up to four molecules of $O_2$ for transport.

Leukocytes

White blood cells that function in defense by phagocytizing bacteria or mounting immune responses.

Platelets

Cell fragments involved in the blood clotting process (coagulation).

Thrombus

A blood clot that forms within a blood vessel and can potentially block blood flow.

Atherosclerosis

Hardening of the arteries caused by the accumulation of fatty deposits known as plaque.

Myocardial infarction

Damage or death of cardiac muscle tissue resulting from the blockage of one or more coronary arteries; commonly known as a heart attack.

Stroke

The death of nervous tissue in the brain caused by the rupture or blockage of arteries in the head.

Angina pectoris

Chest pain resulting from the partial blockage of the coronary arteries.

Gills

Outfoldings of the body surface that maximize the area for gas exchange in aquatic environments.

Countercurrent exchange

A system in fish gills where blood flows in the opposite direction to water to ensure blood is always less saturated with $O_2$ than the water it meets.

Tracheal system

A network of branching tubes in insects that supply $O_2$ directly to body cells, separate from the circulatory system.

Alveoli

Air sacs at the tips of bronchioles where gas exchange occurs via diffusion between air and capillary blood.

Hemocyanin

A respiratory pigment found in arthropods and many mollusks that uses copper as its oxygen-binding component.

Myoglobin

An oxygen-storing protein found in the muscles of diving mammals.