Blood Pressure

Blood Pressure : Blood pressure is the pressure exerted by the flowing blood on the elastic walls of arteries. Blood flows in closed vessels so it exerts a pressure on the walls of these vessels. As soon as the blood is pumped into the arteries it exerts a pressure on the artery wall .This pressure is known as blood-pressure.

Blood-pressure is measured in two stages.

(1) Systolic Pressure:- It is the higher limit of blood pressure that shows the state of heart (systole) contraction for man this limit is 120 mm Hg (normal)

(2) Diastolic pressure:- It is the lower limit of B.P. that shows the state of heart relaxation (expansion = Diastole) for man this limit is 80 mm Hg (normal)

 The instrument by which we can measure B.P. is called sphygmomanometer.

 In man B.P. is measured in the brachial artery of arm. [- Normal B.P. of a healthy person is 120/80 mm Hg.] 

Hales measured B.P. in horse first of all.


Factors Affecting Blood-Pressure:- B.P. may be affected by following factors.

(1) Exercise:- At the time of physical labour. B.P. is increased.

(2) Emotions and Excitement:- In the state of excitement or emotions B.P. is increased in man. At the time of Adrenal secretion at the time of fear and in some hereditary conditions B.P. is increased.

(3) Contraction of Blood Vessels:- B.P. is increased when contraction takes place in arteries and blood capillaries.

(4) Body posture:- In a laying (relaxing) person B.P. is low as compared to a standing man

(5) Sex:- In women, B.P. is slightly low as compared to men.

(6) Obesity:- In obese persons B.P. is increased.

(7) Age : B.P. increases as the age advances due to increase in vasomotor tone.

Pulse – The pulse is felt in the radial artery present in the wrist of a man. It is also felt in the artery of neck region. The graph of pulse of an artery is marked by an instrument that is called sphygmograph. Pulse pressure is the Pressure difference which generates a pulse. This is  systolic minus diastolic B.P.

The force that blood exerts against the walls of the blood vessel is called as blood pressure.The blood pressure is measured with an instrument known as sphygmomanometer.This pressure is much greater in arteries than in veins because the arteries want to reach all parts of the body with the pressure exerted by the heart.The pressure of blood inside the artery during ventricular systole (contractions) is called as systolic pressure and the pressure in artery during ventricular diastole( Relaxation) is called as diastolic pressure. The normal blood pressure of human is 120/80mmHg which means that 120mmHg of systolic pressure and 80mmHg of diastolic pressure. High blood pressure is also called as hypertension and it is caused by the constriction of arterioles which results in increased resistance to blood flow.It can lead to rupture of an artery and internal bleeding.