Principles of Homeostasis

  • Created by: portia
  • Created on: 26-04-17 12:28

Mammals keep their internal environment relatively constant, so providing steady and appropriate conditions within which cells can carry out their actvities. This is known as homeostasis. 

Homeostatic balance requires receptors that detect changes in physiological factors such as the temperature, water potential and pH of blood.

Effectors are the cells, tissues and organs (including muscles and glands) that carry out the functions neccessary to restore those factors to their set points

Homeostatic control systems use negative feedback in which any change in a factor stimulates actions by effectors to restore the factor to its set point

Some physiological factors controlled in homeostasis in mammals are;

  • core body temperature
  • metabolic wastes, particularly carbon dioxide and urea
  • blood pH
  • blood glucose concentration
  • water potential of the blood
  • blood concentration of respiratory gases, oxygen and carbon dioxide

The internal environment of an organisim refers to all the conditions inside the body and are the conditions in which the cells function. For a cell, its immediate environment is the tissue fluid surrounding it.

Generally, homeostatic mechanisms work by controlling the compostion of blood, which therefore controls the composition of tissue fluid.

There are control mechanisms for the different aspects of the blood & tissue fluid including;

  • temperature- low temperatures slow down metabolic reactions; at high temperatures proteins, including enzymes, are denatured and cannot function
  • water potential - if the water potential decreases, water may move out of cells


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