# Long answer question: What is blood pressure? How is it measured? Explain factors affecting blood pressure. - Biology

What is blood pressure? How is it measured? Explain the factors affecting blood pressure.

#### Solution

The pressure exerted by blood on the wall of the blood vessels is called blood pressure.
It is measured by the sphygmomanometer. It is usually measured from the arteries.

The factors affecting blood pressure are:

1. Cardiac output:
The normal cardiac output is 5 litres/min. An increase in cardiac output increases systolic pressure.

2. Peripheral resistance:
It depends upon the diameter of blood vessels. A decrease in the diameter of arterioles and capillaries under the effect of vasoconstrictors like vasopressin or ADH causes an increase in peripheral resistance and thereby increase in blood pressure.

3. Blood volume:
Blood loss in accidents decreases blood volume, and thus the blood pressure.

4. Viscosity of blood:
Blood pressure is directly proportional to the viscosity of blood.

5. Age:
Blood pressure increases with age due to an increase in the inelasticity of blood vessels.

6. Venous return:
The amount of blood brought to the heart via the veins per unit time is called the venous return. It is directly proportional to blood pressure.

7. Length of blood vessel:
Blood pressure is also directly proportional to the total length of the blood vessel. Blood pressure can also be affected by vasoconstriction or vasodilation.

8. Gender:
Females have slightly lower BP than males before the age of menopause. However, the risk of high B. P. increases in the females after menopause sets in.

Concept: Blood Pressure (B.P.)
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#### APPEARS IN

Balbharati Biology 12th Standard HSC for Maharashtra State Board
Chapter 8 Respiration and Circulation
Exercises | Q 7.09 | Page 181