Question

Given diagram shows a simple diagram of the circulation of blood in a mamma showing the main blood vessels, the heart, lungs and body tissues. The blood vessel, labelled 6, contains deoxygenated blood and the valve leading to it has three semi-lunar pockets.

(a) Name the blood vessels and organs marked by numbers 1 to 8.

(b) What is meant by the term ‘double circulation’ of blood in mammals?

(c) what is diastole?

[There is an “error” in the diagram. According to the usual practice the pulmonary (lung) circulation is shown upward and the systemic downward, but here it is reversed].

Answer 1

(b) Blood flows twice in the heart before it completes one full round. The full round thus includes pulmonary and systemic circulation. For this reason, the blood circulation in the human body is called double circulation.

The relaxation of muscles of ventricles or auricles is known as diastole