HOMEOSTATSIS, HOMEOSTATIC FACTOR AND ROLE OF DIFFERENT SYSTEMS OF OUR BODY IN MAINTAINANCE OF HOMEOSTASIS

HOMEOSTATSIS, HOMEOSTATIC FACTOR AND ROLE OF DIFFERENT SYSTEMS OF OUR BODY IN MAINTAINANCE OF HOMEOSTASIS:

What is Homeostasis?

Homeostasis means maintenance of static or constant conditions in the internal environment of cells, That is the 'milieu interior'.

What is ‘milieu interieur’?

Cells live in the environment of extracellular fluid and this extracellular fluid is called ‘milieu interieur’.

Maintaing a constant internal environment is very necessary, so in this regard some factors must be in control.

These factors include:

■pH.

■Temperature.

■Electrolyte concentrations.

■Supply of nutrients.

■Supply of O2.

■Hormone levels.

■Metabolic end products.

■Water content.

How homeostasis is maintained?

Almost all the systems of the body are involved in maintainance of contant internal conditions.

1. Circulatory system:

Nutrients and O2 from extracellular fluid are constantly utilized by the cells. Waste products from the cell constantly diffuse from cells to the extracellular fluid. This changes the composition of extracellular fluid. For maintaining constancy in this fluid, the body has circulatory system which causes constant flow of blood to various tissues. In tissues, blood passes through capillaries which are thin walled and can cause exchange of materials very easily. There is diffusion of nutrients 

and O2 from blood to interstitial fluid and the waste products in the opposite direction. 

Also there is a constant exchange of fluid from blood and extracellular fluid. Small 

amount of protein-free plasma comes out of capillaries at the arterial end and almost equal quantity is absorbed at the venous end. Th us circulatory system causes circulation of blood to different tissues and allows constant exchange of materials between blood and the interstitial fluid.

2. Respiratory system:

 Blood is also circulated to lungs. It picks up O2 in the alveoli needed for the cell. CO2 from blood diffuses out in alveoli of lungs for excretion.

3. Gastrointestinal tract. 

Large amount of blood is pumped by the heart to the wall of gastrointestinal tract. Here different digested materials such as amino acids, fatty acids, glucose, etc. are absorbed from lumens of the gastrointestinal tract into the blood. Thus nutrients required for cells are obtained. All the substances which are absorbed may not be utilized by the cells. The absorbed substances fi rst pass to the liver which changes the chemical compositions of some of them and make them utilizable by the tissue cells. Liver can also store the excess materials for future use.

4. Musculoskeletal system:

Th is allows the person to move to appropriate places either for obtaining food, water or for protection against adverse surroundings.

5. Kidneys:

Water and water soluble waste products are selected from the blood and 

are excreted by kidneys in urine. Kidneys assist in the maintenance of water balance, 

electrolyte balance with the help of endocrine system. Kidneys also help in regulation 

of pH of the extracellular fluid.

6. Hormonal system (Endocrine glands): Each endocrine gland secretes hormone or hormones, which are transported to all the parts of the body in the extracellular fluid. 

Hormones regulate metabolic functions of diff erent body cells, e.g. insulin controls 

glucose metabolism. Adrenocortical hormones control levels of different ions and protein metabolism. Parathyroid hormone controls calcium level of extracellular fluid and also the bone metabolism.

7. Nervous system:

It is composed of the sensory portion, the central nervous system 

(CNS) which is the integrator, and the motor portion.Sensory portion receives information from the surroundings, e.g. eyes give visual image of the surrounding area, ears hear the sounds. Brain and spinal cord form the CNS which collects and stores the information received from sensory portion, can generate thoughts, determines the plan of action in 

response to sensory stimulation.

Motor system receives information from brain and spinal cord about its plan of 

action and the actions are actually executed by the motor system (which mainly supplies skeletal muscles and causes movements as desired by the person).

8. Reproductive system: 

It helps to maintain static conditions by generating new 

beings to take the place of ones that are dying.