06: The Circulatory System : Icse-x-biology

with Solutions - page 2

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#5-c
The blood groups of both the donor and recipient must be known before transfusing blood.
Ans : During blood transfusion it is important that the blood groups of the donor and the recipient are compatible. In case of an incompatible blood transfusion, the recipient develops antibodies that attack the antigens present on the RBCs of the donor causing the blood cells to clump together which may result in death. The examination of Rh factor is also necessary for the blood transfusion. Therefore, the blood groups of both the donor and recipient must be known before transfusing blood.

#5-d
Only the veins and not the arteries are provided with valves.
Ans : Veins carry the blood from the body part towards the heart while the arteries carry the blood from the heart. Veins carry the blood against the force of gravity. Therefore, only the veins and not the arteries are provided with valves.

#5-e
Atrial wall is less muscular than the ventricular wall.
Ans : Atrial wall is less muscular than the ventricular wall because the major function of atria is to receive blood from the body and pump in into very next ventricles. While the ventricles pump the blood out of the heart. Right ventricle to the lungs and the left ventricle to all the body parts.

#5-f
The arteries are deep seated in the body
Ans : Arteries are responsible to carry oxygenated blood from the heart to the tissues. The blood flows in the artery under high pressure and in spurts. If arteries are located superficially then there is a high possibility of their damage which could lead to a lot of blood loss. To prevent this damage and blood loss, the arteries are deep seated in the body.E. Structure/Application/Skill Type

Qstn #1
Given below are the diagrammatic sketches of two kinds of blood vessels.

#1-a
Identify the two kinds of blood vessels A and B.
Ans : A is artery, B is vein.

#1-b
name the parts numbers 1 to 6
Ans : 1- Endothelium of the artery,
2 - Middle layer of smooth muscles and elastic fibres of the artery, 3 - External layer of connective tissue of the artery, 4 - Endothelium of the vein, 5 - Middle layer of smooth muscles and elastic fibres of the vein,
6 - External layer of connective tissue of the vein.

#1-c
Mention any two main differences between A and B.
Ans : An artery has thick muscular walls and a narrow lumen. It carries blood away from the heart towards any organ. A vein on the other hand has thin muscular walls and a wider lumen. It carries blood away from an organ towards the heart.

Qstn #2
Given below is a highly schematic diagram of the human blood circulatory sytem.

#2-a
which part (state the number) represents the heart? Give reason in support of your answer.
Ans : The structure 3 represents the heart. It forms the centre of double circulation and is located between the liver and the head (as per the diagram). Also, the blood circulation (indicated by 1) begins from heart to lungs.

Qstn #3
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.

#3-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].
Ans : 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.