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Homeostasis: An Introduction and the Negative Feedback Mechanism (1)- WRP…
Homeostasis: An Introduction and the Negative Feedback Mechanism
(1)- WRP Bio: Avantika
Homeostasis:
Homeostasis
is the
maintenance of a constant internal environment.
It is very much important
to keep the tissue fluid composition within narrow limits
. This is because
tissue fluid is the place where movement of molecules takes place.
If it becomes
too concentrated
, the body withdraws water from the cells by osmosis (which gives a
dehydrated
feeling). If it is
too dilute
then
the cells take up too much water and become swollen.
We also know that
enzymes are very sensitive
to conditions which they work in. A
slight change in the pH or the temperature
and it may
slow down or stop
an enzyme from working. It would
prevent an important reaction from taking place in the cell.
Thus, homeostasis is important.
Many systems help in homeostasis:
The
kidneys
remove substances which may poison the enzymes.
It also
controls the level of salts, water and acid in the blood.
This composition affects the
tissue fluid
, which
affects the cells.
Another homeostatic organ is the
liver
. It regulates the
level of glucose in the blood
, or turns
glycogen into glucose if the concentration is too low.
If it drops down too
low
, then the person may become
unconscious
and would
die
if the
levels are not restored back
. This shows
how important homeostasis is.
Temperature regulation us another example of homeostasis.
Maintenance of a
constant body temperature
makes sure that vital
chemical reactions continue at a predictable rate and do not speed up or slow down
when the
surrounding temperature changes.
The lungs, too, regulate the levels of oxygen and carbon dioxide in the blood.
The negative feedback mechanism:
Deviation from the set point.
Deviation acts like a signal to the control centre (Brain).
The control centre sets off the correct responses.
Responses cancels or 'negates' (That's why it is known as negative feedback system) and returns the factor to the set point.
Negative feedback system in case of a higher glucose level than normal
Excess glucose level
(acts as a signal).
Brain
(Control centre)
The pancreas islets secrete insulin
(response)
Insulin reaches the liver. Excess glucose is converted back to glycogen.
Normal levels are restored
(Back to the set point).
Negative feedback system in case of a lower glucose level than normal
Less sugar in blood
(acts as a signal).
Brain
(Control centre)
Pancreas islets secrete glucagon
It reaches the liver. Stored glycogen is converted to glucose.
(Response). .
Normal level restored.