Homeostasis is a condition of balance in the body’s internal environment, due to the regular interaction of body’s regulatory processes. In response to the changes in the external environment, the equilibrium of the body is altered. For Example:- blood glucose level normal range is 70-110mg/100ml of blood. If this level falls or rises, then it causes problems.
Firstly, the body itself tries to bring the condition back to normal. But sometimes when the condition becomes severe, then body shows symptoms and we take appropriate treatment to bring the condition back to homeostasis.
Control Of Homeostasis
Homeostasis in the human body is disturbed very often. The three major factors which disturbs the homeostasis are:-
- Social environment:- This is a phycological stress
- External environment:- example heat, temp, lack of O2 etc.
- Internal environment:- example low blood glucose, high or low BP etc.
Sometimes, the disruptions is mild and temporary and is quickly restore by body cell itself; but sometimes these disruptions are severe and prolonged and can lead to severe infections, surgery etc.
A feedback system is a cycle of events In which the body status is monitored, evaluated, changed, re-monitored, reevaluated and re-changed.
1. Each variable which is monitored like temp, BP, sugar level etc are known as controlled condition.
2. Any disruptions which changes the control condition is known as stimulus.
3. The three basic components of feedback system are:
- receptor: which monitors the changes and then sends input to the control center
- control center:- sets the range within which the controlled condition should be maintained; receives input; and then generates output as nerve impulses or hormones.
- Effector:- it receives the output and then produces the response.
There are two types of feedback system-
- Positive feedback system
- Negative feedback system
|Positive feedback system||Negative feedback system|
|It is a feedback system which results in amplification or growth of output signal||It is a feedback system which results in the inhibition or slowing down of the output signal|
|It often leads to breakdown of homeostasis||It always maintains the condition of homeostasis|
|It is less common and occur in specific situation||It occurs more often in the body|
|Example: childbirth after 7th or 9th month pregnancy||Example: regulation of BP|
Example of negative feedback system is described in below image:
Above Image is taken from chromoscience.com, for education purpose only
Example of positive feedback system is described in image below:-
Multiple choice questions(MCQs)
1. The condition of equilibrium in the body is known as?
A. hemostasis B. homeostasis
C. translation D. transcription
2. Do the body cells also try to bring the condition back to normal?
A. always B. yes when condition is severe
C. sometime when condition is mild D. never
3. What factor disturbs the homeostasis?
A. social environment B. internal environment
C. external environment D. all of the above
4. Match the following-
A. receptor 1. Receives input
B. stimulus 2. Generated input
C. control center 3. Disruptions caused in control condition
D. effector 4. Produces response
5. What is the work of feedback system?
A. monitor, change, evaluate
B. evaluate, change monitor
C. change, monitor, evaluate
D. monitor, evaluate, change
6. Which of the following is an example of positive feedback system?
A. childbirth B. control f BP
C. control f glucose level D. all of the above
7. Which of the following statement is NOT true?
A. severe disruption in homeostasis can even lead to surgery
B. positive feedback is growth of output signal
C. childbirth after 8th month pregnancy is positive feedback
D. output is generated in form of hormones and nerve impulses
8. What is the controlled condition?
A. in receives the input B. disruptions caused in homeostasis
C. variable which is monitored D. receives output
9. What factors comes under social environment which disturb homeostasis?
A. temp B. lack of o2
C. blood glucose level D. none of the above
10. What happens if the effector is blood vessel and causes vasodilation?
A. increases BP b. decreases BP
C. increases blood sugar level D. decreases blood sugar level
- sometimes when the condition is mild
- all of the above
- A – 2 B – 3 C – 1 D – 4
- monitor, evaluate, change
- childbirth after 8th month pregnancy is positive feedback
- variable which is monitored
- none of the above
- decreases BP
REFERENCE:- Gerard J. Tortora -Principles of anatomy and physiology; edition twelfth ; page no.-: 8-11.