Blood pressure:

The pressure of blood against the walls of vessels due to the flow of blood in them is called blood pressure.

• It is high in arteries, some less in capillaries & arterioles and very low in veins.
• Rise in blood pressure during the contraction of heart is called systolic pressure.
•  Fall in blood pressure during relaxation of heart is called diastolic pressure.
• An instrument which is used to measure blood pressure is sphygmomanometer.
•  The average systolic/diastolic pressure is 120/80 mm of Hg in a healthy person.

Hypertension: Rise in BP is called high blood pressure or hypertension. Occur by the narrowing of arteries or when arteries loose elasticity in old age etc.

Hypotension:  Fall in BP is called low BP or hypotension. Occurs by expansion of arteries or by blood loss due to injury etc.

                      Sphygmomanometer