1. BODY TEMPERATURE REGULATION AND FEVER

2. There is no single body temperature because temperature varies from organ to organ.
Outer body temperature
Outer shell
Skin & subcutaneous tissues
Central core
Core temperature
Abdominal ,thoracic organs, CNS &Skeletal muscles

3. Outer body temperature
Outer shell
May vary.
Fluctuate
Central core
Core temperature
Precise regulation.
F when measured orally.

4. DEPEND UPON BALANCE BETWEEN HEAT PRODUCTION AND HEAT LOSS
CONTROL OF BODY TEMPERATURE 
DEPEND UPON BALANCE BETWEEN HEAT PRODUCTION AND HEAT LOSS
Heat production
Heat loss

5. Heat production depends upon rate of metabolism by;
All body cells
Thyroxin, GH, testosterone.
Epinephrine, norepinephrine and sympathetic stimulation.
Increase chemical activity

6. How rapidly heat can be conducted from body core to skin.
Heat loss
How rapidly heat can be conducted from body core to skin.
How rapidly heat can be conducted from skin to surrounding.

7. How rapidly heat can be conducted from body core to skin.
Profuse blood supply beneath skin.
Large numbers of vessels are present beneath the skin.
These are responsible for increase in rate of blood flow
Thus increase rate of conduction from body core to skin.
Sympathetic stimulation of arterio-venous anastomosis and arteries
This stimulation cause vasoconstriction of all vessels other than that to heart, brain and working muscle.
Thus there is decrease in rate of blood flow.
Decrease in rate of heat conduction from body core to skin.

8. 2. How rapidly heat can be conducted from skin to surrounding.
Radiation /infrared heat rays
Conduction
Convection
Evaporation

9. Radiation /infrared heat rays (60%)
Human body radiates heat in all directions.
Heat is also radiated from walls of room and other objects toward body.
But if body temperature is more than environment then greater quantity of heat is radiated from body.

10. Conduction
Direct Loss of heat from surface of body to solid objects (chair/bed 3%).
Direct loss of heat from body surface to air (15%)

11. Convection
Molecules of skin are in constant vibratory motion.
This energy of motion transfer only when air is cooler than skin.
When temperature of air =temperature of skin→ no heat loss.

12. So heated air should continuously move away from skin and new air should bring in contact with skin→ air movement (air convection/air current).
In case of wind→ increase air convection→ increase heat loss.

13. Evaporation (22%)
Sweating from skin and loss of water from lungs.
When temperature of surrounding is more than skin→ body gain heat by conduction and convection→ now only mean of losing heat is by evaporation.

14. Local skin temperature reflexes
REGULATION OF BODY TEMPERATURE 
Behavioral control
Local skin temperature reflexes
Increase in internal body temperature→ signals from temperature controlling area of brain→ give person a psychic sensation of feeling overheated.
Conversely in severe cold→ receptors from skin and deep tissues detect cold→ person make appropriate environmental and cloth adjustment.
When a person places foot under a hot lamp for short time→ local vasodilation and local sweating occur.
Conversely placing the foot in cold water→ local vasoconstriction and cessation of sweating occur.
Role of hypothalamus

15. REGULATION OF BODY TEMPERATURE
ROLE OF HYPOTHALAMUS
ROLE OF ANTERIOR HYPOTHALAMUS
ROLE OF POSTERIOR HYPOTHALAMUS

16. ROLE OF ANTERIOR HYPOTHALAMUS
Increase in body temperature
Stimulation of pre-optic area of anterior hypothalamus
Send nerve impulse to spinal cord through autonomic pathways
Inhibition of sympathetic center in posterior hypothalamus that cause vasoconstriction
Inhibition of shivering
Then through sympathetic outflow to skin
Vasodilation of skin blood vessels
Release of epinephrine/norepinephrine
Increase heat transfer from core to skin
Stimulate sweat glands
Sweating
INCREASE HEAT LOSS

17. ROLE OF POSTERIOR HYPOTHALAMUS Cold Signal from skin & deep tissues
ROLE OF POSTERIOR HYPOTHALAMUS
Cold Signal from skin & deep tissues
Decrease in body temperature
Stimulation of dorsomedial portion of posterior hypothalamus/primary motor center of hypothalamus
Stimulation of sympathetic center in posterior hypothalamus
Cooling of ant. hypothalamic
pre-optic area
Vaso- constricti on of skin blood vessels
Arrector pili muscles attached to the hair follicles contract
Release of norepinephri ne
↑ TRH from hypothalamus
Stimulate brown fat in animals/neo nate which contain large number of mitochondri a
Transmit signals through lateral column of spinal cord
Decrease heat transfer from body core to skin
Upright projection of hairs allows them to trap heat
Stimulate release of TSH from anterior pituitary gland
Stimulation of anterior motor neurons
Increase tissue expression of thermogenin (mitochondri al coupling protein)→↑ heat production
Increase muscle tone
Stimulate release of thyroxin by thyroid gland →↑ metabolic rate
Shivering
Increase heat production
DECREASE HEAT LOSS

18. ROLE OF POSTERIOR HYPOTHALAMUS
Decrease in body temperature
Stimulation of sympathetic center in posterior hypothalamus
Vaso- constriction of skin blood vessels
Arrector pili muscles attached to the hair follicles contract
Release of norepinephrine
Stimulate brown fat in animals/neonate which contain large number of mitochondria
Decrease heat transfer from body core to skin
Upright projection of hairs allows them to trap heat
Increase tissue expression of thermogenin (mitochondrial coupling protein)→↑heat production
DECREASE HEAT LOSS

19. ROLE OF POSTERIOR HYPOTHALAMUS
ROLE OF POSTERIOR HYPOTHALAMUS
Cold Signal from skin & deep tissues
Decrease in body temperature
Stimulation of dorsomedial portion of posterior hypothalamus/primary motor center of hypothalamus
Stimulation of sympathetic center in posterior hypothalamus
Cooling of ant. hypothalamic
pre-optic area
Vaso- constricti on of skin blood vessels
Arrector pili muscles attached to the hair follicles contract
Release of norepinephri ne
Stimulate brown fat in animals/neo nate which contain large number of mitochondri a
↑ TRH from hypothalamus
Transmit signals through lateral column of spinal cord
Decrease heat transfer from body core to skin
Upright projection of hairs allows them to trap heat
Stimulate release of TSH from anterior pituitary gland
Stimulation of anterior motor neurons
Increase tissue expression of thermogenin (mitochondri al coupling protein)→↑ heat production
Increase muscle tone
Stimulate release of thyroxin by thyroid gland →↑ metabolic rate
Shivering
Increase heat production
DECREASE HEAT LOSS

20. Fever is defined as body temperature above usual normal range.
Caused by any brain abnormality or by toxic substances (pyrogens ) that effect the temperature regulating center.

21. FEVER Bacteria or breakdown product of bacteria→
phagocytized by leuckocytes,tissue macrophages or granular killer lymphocytes→
digest bacterial products→
release cytokines (interleukin-1)→
cause formation of prostaglandins E2→
act on hypothalamus→
Cause set point to raise→
FEVER

22. Chills
If set point of hypothalamic control raise to high value→ body temperature rise in response→ during this period ,person experience extremely cold ,chills and shivers.

23. Crisis/Flush
When the factor causing high temperature is removed→ set point reduced to low level→ now body temperature is at high level ,so body try to lower its temperature→during this period person experience intense sweating→these change of events is known as crisis or flush.

24. Circulatory shock due to excessive loss of fluid and electrolytes.
Heatstroke
When body temperature rises beyond a critical temperature into the range of 105 0F to 1080F, Heatstroke develops.
Symptoms include dizziness, abdominal distress and loss of consciousness.
Circulatory shock due to excessive loss of fluid and electrolytes.
Damage to brain and body tissues.

25. Reason:
At this very high temperature, temperature regulating mechanism often fail.
Increase body temperature doubles the rate of all intracellular chemical reactions, thus liberating more heat.

26. Treatment:
Remove all clothing.
Cool water spray
Cool water sponging
Immersion of body in chilled water if available.

27. Exposure of body to extreme cold
When body temperature falls below 940C, the ability of hypothalamus to regulate body temperature is lost.
Reason: decrease rate of chemical reactions.
Decrease activity of central nervous system to control heat mechanism and prevent shivering.

28. FROSTBITE
When body is exposed to extremely low temperature, surface area freeze.
Occur in lobes of ear and in digits of hand and feet.
Ice crystal form in the cells, local tissue damage and permanent circulatory impairments + gangrene

29. THANKS