1. Maintenance of internal environment constant

7. Cont... Mechanisms that raises the body temperature are: 1- stimulation of skeletal muscle causes shivering. 2- narrowing of the blood vessels in the skin reducing the blood flow to, and heat loss from the peripheries. 3- behavioural changes, e.g, we put on more clothes or curl up. Most of the homeostatic controls in the body use negative feedback mechanisms to prevent sudden and serious changes in the internal environment.

9. Example of Positive Feedback Mechanism

19. Body temperature fairly remains constant 36.8 0 C. It raised slightly in the evening, during exercise, and in women just after ovulation. When the rate of metabolism rises temperature increases. To ensure this constant temperature, a balance is maintained between heat production in the body and heat lost to the environment.