A diagram of the circulation of a fish. Labels: 1, The pericardium. 2, The single auricle. 3, The single ventricle. 4, The vessel that conveys the blood from the ventricle to the gills. 5, The vessel that conveys the blood from the body to the heart. The arrows show the direction of the blood.

Circulation of a Fish

A diagram of the circulation of a fish. Labels: 1, The pericardium. 2, The single auricle. 3, The single…

A diagram of the circulation of a frog. Labels: 1, The pericardium. 2, The single ventricle. 3, The right auricle. 4, The left auricle. The arrows indicate the direction of the blood.

Circulation of a Frog

A diagram of the circulation of a frog. Labels: 1, The pericardium. 2, The single ventricle. 3, The…

Insects have neither arteries nor veins. The circulation, such as it is, is animated by the action of a vessel called dorsal, which is situated above the digestive tube. Labels: 1, Dorsal vessels in which the blood flows. 2,The lateral currents. The arrows show the outward and the inward current.

Diagram of the Circulation of an Insect.

Insects have neither arteries nor veins. The circulation, such as it is, is animated by the action of…

A diagram illustrating the circulation of the blood. Labels: A, vena cava descending (superior); Z, vena cava ascending (inferior); C, right auricle; D, right ventricle; E, pulmonary artery; F, P, lungs and pulmonary veins; G, left auricle; H, left ventricle; I, K, aorta.

Circulation of Blood

A diagram illustrating the circulation of the blood. Labels: A, vena cava descending (superior); Z,…

The circulatory organs. Labels: 1, The left auricle. 2, The right auricle. 3, The left ventricle. 4, The right ventricle. 5, 6, The aorta. 7, The femoral (leg) artery. 8, The branchial (arm) arteries. 9, carotid arteries. 10, The jugular veins. 11, The branchial veins. 12, The femoral veins. 13, 14, The vena cavas. 15, The pulmonary artery. 16, The right and left pulmonary arteries. 17, The pulmonary veins. 18, The lacteals. 19, The thoracic duct. 20, The absorbents of the upper extremities. 22, The small intestine.

The Circulatory Organs

The circulatory organs. Labels: 1, The left auricle. 2, The right auricle. 3, The left ventricle. 4,…

Diagram of the circulatory system, showing that it forms a single closed circuit with two pumps in it, represented by the right and left halves of the heart, which are separated in the diagram. Labels: ra and rv, right auricle and ventricle; la and lv, left auricle and ventricle; ao, aorta; sc, systemic capillaries; vc, vena cava, pa, pulmonary artery; pc, pulmonary capillaries; pv, pulmonary veins.

Diagram of the Circulatory System

Diagram of the circulatory system, showing that it forms a single closed circuit with two pumps in it,…

In the class of Crustacea there is a single ventricle, which receives the blood from the gills and propels it to other parts of the body. Shown is the heart and arteries of a lobster. Labels: 1, The heart. 2, The abdominal artery. 5, Venous sinuses. 6, The branchia from which the blood returns to the hear.

The Heart and Arteries of a Lobster

In the class of Crustacea there is a single ventricle, which receives the blood from the gills and propels…

In high orders of Mollusca the circulation resembles that of fish. Shown is the heart and arteries of a snail. Labels: 2, The stomach. 3, Intestines. 5, Heart. 6, Aorta. 7, Pulmonary artery.

The Heart and Arteries of a Snail

In high orders of Mollusca the circulation resembles that of fish. Shown is the heart and arteries of…