Homeostasis

In Physiology, homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits

2. HOMEOSTASIS

3. HOMEOSTASIS
By
Dr. K. Ambareesha .,PhD (Med Physio)
Department of Physiology
MNR Medical College

4. OBJECTIVES
1.Definition
2.Milieuinterior
3.ContributionsofthebodysystemstoHomeostasis
4.Componentsofhomeostaticsystem
5.Factorshomeostaticallyregulated
6.Homeostaticcontrolsystems
7.Mechanismsofactionofhomeostaticsystem
8.Disruptionsinhomeostasiscanleadtoillnessanddeath

5. DEFINITION
“The various
physiologic
arrangement which
serve to restore the
normal state, once it
has been disturbed”
W.B. canon coined the
term homeostasis in
1930.

6. HOMEOSTASIS
MILIEU INTERIEUR :
•The importance of internal
environment was notified by the
great biologist of 19
th
century
Claude Bernard.
•He enlightned the fact that
multicellualr organisms including
man live in a perfectly organized
and controlled internal
environment.

7. Homeostasis is essential for survival of each cell and
each cell, through its specialized activities, contributes
as part of a body system to the maintenance of the
internal environment shared by all cells.

8. Contributions of the body systems to homeostasis
The 11 body systems contribute to homeostasis in the
following important ways
The circulatory
system is the
transport system
that carries
materials such as
nutrients, o2’ C02,
wastes, electrolytes,
and hormones from
one part of the body
to another

9. 2. The digestive system
breaks down dietary
food into small nutrient
molecules that can be
absorbed into the
plasma for distribution
to the body cells.

10. 3. The respiratory system
obtains O2 from and
eliminates CO2 to the
external environment.
By adjusting the rate of
removal of acid-forming
C02, the respiratory
system is also important
in maintaining the proper
pH of the internal
environment.

11. 4. The urinary system
removes excess water,
salt, acid, and other
electrolytes from the
plasma and eliminates
them in the urine,
along with waste
products other than
CO2.

12. 5. The skeletal system provides
support and protection for the
soft tissues and organs. It also
serves as a storage reservoir for
calcium (Ca2+), an electrolyte
whose plasma concentration
must be maintained within very
narrow limits.
Skeletal muscle contribute to
homeostasis by playing major
role in the procurement of food
breathing heat generation for
maintenance of body
temperature and movement away
from harm

13. 6. The muscular system
moves the bones to which
the skeletal muscles are
attached.
From a purely homeostatic
view, this system enables an
individual to move toward
food or away from harm

14. 7. The integument system
serves as an outer protective
barrier that prevents internal
fluid from being lost from the
body and foreign micro-
organisms from entering.
The amount of heat lost from
the body surface to the
external environment can be
adjusted by controlling sweat
production and by regulating
the flow of warm blood
through the skin.

15. 8. The immune system defends
against foreign invaders and
against body cells that have
become cancerous. It also
paves the way for repair or
replacement of injured or worn-
out cells.

16. 9.Thenervoussystemisoneof
thetwomajorregulatorysystems
ofthebody.
Itisespeciallyimportantin
detectingandinitiatingreactions
tochangesintheexternal
environment.
Furthermore,itisresponsiblefor
higherfunctionsthatarenot
entirely directed toward
maintaininghomeostasis,suchas
consciousness, memory, and
creativity.

17. 10. The endocrine system is
the other major regulatory
system. In contrast to the
nervous system, in general
the hormone secreting
glands of the endocrine
system regulate activities
that require duration rather
than speed. This system is
especially important in
controlling the
concentration of nutrients.

18. 11.Reproductive system is not essential for
homeostasis and therefore is not essential
for survival of the individual. Its essential for
perpetuation of species

19. Homeostatic system in
the body acts through
self-regulating
devices, which
operate in a cyclic
manner.
This cycle includes
three components:
Detectors or sensors,
which recognize the
deviation
COMPONENT OF HOMEOSTATIC SYSTEM

20. Transmission of this message
to an integrating unit or
control center
Transmission of information
from the control center to the
effectors for correcting the
deviation
The transmission of the
message or information may
be an electrical process in the
form of impulses through
nerves or a chemical process
in the form of mainly
hormones through blood and
body fluids.
COMPONENT OF HOMEOSTATIC SYSTEM

21. FACTORS HOMEOSTATICALLY
REGULATED
1.Concentration of oxygen and
carbon dioxide
2.pH of the internal environment
3.Concentration of nutrients and
waste products
4.Concentration of salt and other
electrolytes
5.Volume and pressure of
extracellular fluid
6.Temperature

22. HOMEOSTATIC CONTROL SYSTEM

23. Mechanism of action of homeostatic
system
1.Negative feed back
2.Positive feed back

24. 1.Negative feed back mechanism –secretion of thyroxine

25. 1.Negative feed back mechanism –maintenance of water balance

28. Disruptions in Homeostasis can lead
to illness and death
Successful
compensation
–Homeostasis
reestablished
Failure to
compensate
–Pathophysiology
Illness
Death

29. THANK YOU