Question

Given below is a simple diagram of the circulation of blood in a mammal showing the main blood vessels, the heart, lungs, and body tissues. The blood vessel labeled 6 contains deoxygenated blood and 2 the valve leading to it has three semi-lunar pockets.

(i) Name the blood vessels of organs marked by numbers 1 to 8.
(ii) What do you mean by the term ‘double circulation’ of blood in mammals?
(iii) What is diastole?

Answer 1

(i)
1. Veins from tissues.
2. Superior vena cava
3. Aorta
4. Right ventricle
5. Left ventricle
6. Pulmonary Artery
7. Pulmonary vein
8. Lungs.
(ii) The heart is said to have double circulation because the blood passes through the heart twice.
(a) It first leaves t.rough the right ventricle, goes to the lungs and then returns to the left auricle of the heart (pulmonary circulation).
(b) It leaves through the left ventricle, circulates through the body, and again returns to the right auricle of heart (systemic circulation).
(iii) Diastole is the phase of relaxation of the heart muscles during which the heart chambers fill with blood and the supply of blood to the cardiac muscle is improved.