1.1.Homeostasis Chapter:-
Content:-
1. Definition of Homeostasis
2. Different organ and organ system involved in the maintenance of body’s internal environment
3.Functions of various organ systems in homeostasis
4. Summary of the chapter
5. Important Questions from Homeostasis Chapter
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Check here for:-
Chapter 1.2- Homeostasis and the mechanism involved
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1. Definition of Homeostasis
Greek words; Homeo = ‘unchanging’ and Stasis = ‘standing’
- In its simplest form it means ‘staying the same’
- It is an organism’s internal environment which ‘stays the same’
- In practice, it comes down to providing a stable environment for the cells of the body
- So, a better definition of ‘homeostasis’ is the "maintenance of the internal environment within narrow limits".
Best Examples for Homeostasis:-
-When we are too cold we shiver, it warms us up.
-When we are too hot we sweat, it cools us down.
-When we are too hot we sweat, it cools us down.
- The living processes in the cells depend on the activity of enzymes.
- These enzymes work best in specific conditions such as those of temperature and pH.
- Any change in these conditions affects the function of the enzymes and may lead to the death of the cells or, ultimately, the whole organism
- Internal conditions are not absolutely constant, but allowed to vary within very narrow limits.
- Ex: Human body temperature varies between 36.1 – 37.8 °C and that's why the average temperature is usually expressed as 36.8 °C.
2. Different organ and organ system involved in the maintenance of body’s internal environment
- Cardiovascular system.
- Respiratory system.
- Nervous system.
- Endocrine system.
- Gastrointestinal system.
- Excretory system.
- Skeletal system.
- Integumentary system.
- Reproductive system.
3.Functioning of various organ system in homeostasis
3.1. CARDIOVASCULAR SYSTEM:-
- Transports oxygen, carbon dioxide, nutrients and hormones to and from the body cells.
- Helps regulate pH and temperature.
- Provides protection against diseases.
Mechanism:-
- To carry out its living processes, every cell in the body needs a supply of oxygen and food. Waste products such as carbon dioxide have to be removed before they reach harmful levels and damage the cell.
- These conditions are maintained by tissue fluid bathing the cells. Tissue fluid is derived from the blood.
- The tissue fluid contains oxygen and food which the cells can absorb, and also accepts the carbon dioxide and other waste products produced by the cells.
- The blood system maintains the composition of the tissue fluid.
- One important method of achieving homeostasis is Negative feedback.
Negative Feedback applies to many systems in the body. Temperature regulation is one example:-
-If the blood temperature rises, a ‘heat gain’ center in the brain sends nerve
impulses to the skin, which causes vasodilation and sweating, which cool the
blood.
-If the blood temperature falls, it stimulates a ‘heat loss’ center in the brain
which sends impulse to the skin causing vasoconstriction and the cessation
of sweating. These changes reduce heat loss from the skin.
- The warmer or cooler blood provides negative feedback to the thermoregulatory center in the brain.
3.2. RESPIRATORY SYSTEM:-
- Exchange the gases between atmospheric air and blood.
- Help adjust the pH of the body fluids.
3.3 NERVOUS SYSTEM:-
- Generates nerve impulses (Action Potential) that provide communication and regulation of most body tissues.
3.4. ENDOCRINE SYSTEM:-
- Regulates the activity and growth of target cells in the body.
- Regulate metabolism
Mechanism:-
- The glucose concentration in the blood is controlled by the pancreas
- The pancreas contains cells which produce digestive enzymes but it also contains cells such as (alpha and beta cells) which produce the hormones insulin and glucagon respectively.
- If the glucose concentration rises, the beta cells release insulin
- If the glucose concentration falls, the alpha cells release glucagon
- Insulin stimulates the liver and muscles to remove excess glucose from the blood and store it as glycogen
- Glucagon stimulates the liver to convert its stored glycogen into glucose which is then released into the bloodstream
- In this way, the concentration of glucose in the blood is kept within narrow limits.
3.5. GASTROINTESTINAL SYSTEM:-
- Breaks down food into absorbable form.
- Absorbs various nutrients.
- Eliminates waste from the body.
3.6. EXCRETORY SYSTEM:-
- Helps eliminate the waste products from the body.
- Maintains the blood pH, volume, pressure, osmolarity, electrolyte composition etc.
- Produces hormones.
Mechanism:-
- In the cells, the chemical breakdown of proteins produces the nitrogenous compound called as urea. If this were allowed to accumulate in the cells it would damage or kill them.
- The concentration of the blood and tissue fluids tends to vary. If water is lost through evaporation and sweating, the fluids become more concentrated. The intake of water dilutes the fluids.
- It is important that the concentration of blood and tissue fluid is kept within narrow limits if the cells are to function properly. These homeostatic functions are carried out by the kidneys.
- Blood pressure forces tissue fluid out of a clump of narrow capillaries.
- The fluid contains urea, salts, glucose and other soluble substances.
- The fluid trickles down this tubule and the useful substances such as glucose are reabsorbed into the blood.
- In this tubule more or less water is reabsorbed to maintain the blood concentration.
- Excess water, some salts and urea collect here before passing to the bladder as urine.
- Bones provide support, protection, the production of blood cells.
- Muscles produce body movements and produce heat to maintain the body temperature.
3.8. INTEGUMENTARY SYSTEM:-
- Contributes to homeostasis by protecting the body and helping regulate the body temperature
- It also allows you to sense pleasurable, painful and other stimuli in your external environment.
- The sweat gland extracts sweat from the blood and passes it up the duct to the skin surface where it evaporates.
- If the body temperature rises, the blood vessels in the skin dilate (become wider) and allow more blood to flow near the surface. The heat loss from the blood through the skin helps cool the circulating blood.
- Vasoconstriction:-
- If the body temperature falls. The blood vessels in the skin constrict. Less warm blood flows near the surface so less heat is lost.
4. Summary
- Homeostasis = Maintaining body’s internal environment within in a narrow limit.
- Homeostasis is very essential for normal functioning of body.
- Various organs and organ systems play specific roles to achieve homeostasis.
5. Important Questions
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