Page 107 - Science Class 07

Veins : Blood vessels which carry deoxygenated blood from different parts
of the body to the heart

Capillaries : Thin tubes which act as a medium between arteries and veins
Blood transfusion : A process through which blood is transferred from one person to
another

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i All the living organisms have a circulatory system through which oxygen, carbon dioxide
and other materials are transported in the body.
i On average, an adult man has about 15 litres of blood in his body.
i Plasma acts in blood clotting and in defense of the body against disease.

i RBC is formed in the bone marrow.
i WBC is bigger but fewer than the RBC. WBC are also formed in the bone marrow.

i Average weight of heart is about 340 grams in men and 255 grams in women.
I Arota or the big artery carries the oxygenated blood to every part of the body and the
pulmonary artery carries deoxygenated blood to the lungs.

i Different persons have different blood groups such as A, B, AB an O. In case of blood
transfusion, the recipient and the donor must be of the same blood group.
i Pulse rate indicates the number of heart beat.

i In other higher animals, a well-developed circulatory system is present similar to that of
human beings.

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A. Tick (3) the correct op on.
1. Which of the following things is present in blood?
(a) Plasma (b) Haemoglobin
(c) Oxygen (d) All of these
2. How many platelets are present in the blood of a healthy man?
(a) 3,00,000 per cubic ml (b) 1,00,000 per cubic ml

(c) 5,00,000 per cubic ml (d) None of these
3. The lower chamber of the heart is called:
(a) atrium (b) ventricle

(c) aorta (d) artery
4. Which of the following is not a blood group?
(a) A (b) B
(c) C (d) O

Science-7 107