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1. HOMEOSTASIS

2. I NYOMAN ADIPUTRA
• FK UNUD: ‘75 ; dr.
• U HK: 1978-79Advanced Physiology.
• IPH-UP: 1982-83 M.O.H.
• OUMS, Okayama 1983 (industrial hygiene)C.O.H.
• FPS UNAIR: 1988/9-92Doktor
• Sp1: 1990 PFK
• Guru Besar: 1- 02 – 1993 Prof.
• NIWL, Stockholm, 2002/04 Dipl.OSH & D
• LCU, London 1997; MLU, London, 2002.
• PB IAIFI: 2009 Sp1.Erg.
• PB IAIFI: 2011 AIFO

3. HOMEOSTASIS
 Definition: i.e. a state of keeping the internal environment
constant within physiological limits.
 What is the “internal environment”?
- 60% of body is made of body fluids
 “Internal environment” is the;

4. Components of the body fluids

5. CAPILLARY EXCHANGE
 Homeostasis occurs at capillary level.
 Capillaries are the smallest blood vessel ~ one cell thick
 Substances (e.g. nutrients, O2,CO2 and cellular wastes) move down
their concentration gradient across capillary.

6. STRESS AND HOMEOSTASIS
 Stress – is any stimuli (external and internal) disturbing homeostasis
Examples of internal stresses -  blood glucose, and  acidity in ECF
Examples of external stresses - heat, cold, lack of oxygen
 There are variations of stress from mild stress  to extreme stress.
Examples of mild stress - thirst and hunger
Examples of extreme tress - poisoning, severe infection
 For mild stress, cells respond quickly to restore imbalance
 For extreme stress, cells may restore incompletely the imbalance and
can result in chronic illness or even death.
 The body has many homeostatic devices to oppose the stimuli of
stress and restore internal environment

7. STRESS and HOMEOSTASIS

8. WATER BALANCE
• INPUT OUT PUT
In food : 1200 ml Lung : 500 ml
liquid : 1000 ml Kidney :1500 ml
metab.: 400 ml Skin : 450 ml
Faeces : 150 ml
--------------------- ------------------------
2600 ml 2600 ml

9. DISTRIBUTION OF WATER
• ICF 30 LITRES
• ECF 16 LITRES
-Blood plasma 3.5 litres
-interstitial & tissues 12 litres
-lymp node 0.5 litres

10. ALLOSTASIS
• A PROCESS WHERE THE
HOMEOSTASIS IS CHANGED & SET UP
INTO THE NEW VALUE LEVEL.
HOMEOSTASIS
HOMEOSTASIS
• HOMEOSTASIS

14. REGULATION OF HOMEOSTASIS
 The Nervous system and Endocrine system work together or
independently to regulate homeostasis
 1) NERVOUS SYSTEM
- uses nerve impulses to respond to stresses in the body
- response is rapid compare to endocrinal system
E.g. Active muscle contraction – produces  CO2 and  O2 in
blood. Nerve cells detects changes in blood gases  sends
impulses to brain  brain send impulses to heart to  heart
rate  brain also sends impulses to respiratory centre in
brain to  breathing rate  blood gases are quickly
restored back to normal.

15. REGULATION OF HOMEOSTASIS
 2) ENDOCRINAL SYSTEM
– Uses hormones to responds to stresses and to maintain
homeostasis
– Response is slower than nervous system and also is more fine
tuning.
E.g. Active muscle contraction  produces  CO2 and  O2 in
blood   CO2 causes the release of epinephrine into blood
 epinephrine causes  in heart rate  delivery to and
removal of CO2 in lungs .

16. CONTROL MECHANISM FOR HOMEOSTASIS
 The control mechanism for homeostasis is a feedback system.
- FEEDBACK SYSTEM has 3 parts ;
1) CONTROL CENTER
2) RECEPTOR
3) EFFECTOR

17. CONTROL MECHANISM FOR HOMEOSTASIS
1) CONTROL CENTER
- mainly the brain and other parts of the central nervous system
- sets the values at which the controlled condition (E.g. body
temperature) is to be maintained.
2) RECEPTOR
- monitors changes in the controlled condition and sends
information to control center.
(E.g. continuously sends body temperature data to the body
temperature control center in the brain)
3) EFFECTORS
- receives information from controlled center and produces
response to correct stimuli.

18. CONTROL MECHANISM FOR HOMEOSTASIS

19. TWO TYPES OF FEEDBACK LOOPS
1) NEGATIVE FEEDBACK LOOP
2) POSITIVE FEEDBACK LOOP

20. TWO TYPES OF FEEDBACK LOOPS
 1) NEGATIVE FEEDBACK LOOP
- the response reverses original stimuli by
inhibiting it.
- we especially see in conditions that require
frequent monitoring and make adjustment within
physiological limits.
Example:
1. Body temperature and blood glucose level is
regulated by negative feedback system.
2. Release of thyroxine (T3 and T4 hormones) from
thyroid gland.

22.  2) POSITIVE FEEDBACK LOOP
- the response enhances the original stimulus
- we see in conditions that does not require fine-tuning
- usually switched off by mechanisms outside the system
- can be destructive and result in various disorder but some are
normal and beneficial.
Example:
i) Blood clotting. The original signal is amplified until blood
clot forms and bleeding is under control. Then other
substances help turn off the clotting response.
ii) At birth. Positive feedback loop results in strengthening of
labor contractions until the baby is finally delivered.
iii) Immune response. The positive feedback loop causes the
body to amplify the signal and response to contain and
quickly remove the pathogen (disease causing agent) from
the body.

23. E.g. CLOTTING CASCADE

26. THERE IS A DUALISM IN THE
BODY
platelets Anti-platelets
vasodilator V.Constrictor
Brochodilator Br.constrictor
Heat product. Heat-loss
Oxidant Antioxidant
Antigen Anti body
Aging Anti-aging

27. DISEASE :HOMEOSTASIS and IMBALANCE
 Body processes remains within physiological limits body
cells function well homeostasis is maintained body is
healthy.
 But when body processes ( 1 or >1) loose their ability to contribute to
homeostasis. The outcomes would result in;
- (if moderate) diseases results
- (if severe) death results
 LOCAL DISEASES - disease affecting limited part/ region of the body.
 SYSTEMIC DISEASE- disease affecting entire body.
 SYMPTOMS - Subjective changes (complains) in the body function
that a patient complains about, and is not apparent to an observer.
(e.g. pain complaint by patient)
 SIGNS - Objective changes that a clinician can observe and measure.
- SIGNS can be:
(ANATOMICAL changes) – Swelling, rash
(PHYSIOLOGICAL changes) – Raised blood pressure and raised
body temperature