Nutrition, Transportation, Respiration and Excretion

Life Processes-1 Nutrition, Transportation, Respiration and Excretion
young human being, it is about 120 millimetres of mercury (120 mm Hg). When
the ventricles relax, pressure of blood inside the arteries is comparatively less It
is about 80 millimetres of Hg (80 mm Hg) in a healthy young man. Thus, a healthy
young man has a normal blood pressure of 120 / 80 mm of Hg. The instrument used
to measure blood pressure is called sphygmomanometer.
Pulse rate
MODULE - 5
The Living World
Notes
The systemic contraction of the heart can be felt as a jerk in certain arteries like the
radial artery in the wrist and neck artery below the jaw which are superficial in
position. This is called arterial pulse. Pulse rate is the same as the rate of
heartbeat.
ACTIVITY 22. 6
Locate and hold the radial artery present in your wrist. Try and count the number
of beats in a specified time. It is called ‘pulse’ and will give you an idea of the
number of times your heart beats in a minute.
ACTIVITY 22. 7
Visit the local medical centre and get your pulse rate and blood pressure checked
and also that of your family members. Do you find any difference in blood pressure
and pulse rate of your family members?
INTEXT QUESTIONS 22.6
1. Why is a system of transportation/circulation necessary for organisms?
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2. Which kind of blood vessels are responsible for the exchange of nutrients and
respiratory gases between blood and tissues?
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3. What is so special about heart that it continues beating without getting fatigued?
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22.8.2 Circulatory Medium
Our body has three different types of fluids
• Blood—found in heart and blood vessels (arteries, veins and capillaries)
SCIENCE AND TECHNOLOGY
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