Skin: Layers of skin, role of skin during increased temperature and decreased temperature.

1. Role of Skin in Regulation of
Body Temperature

2. The Skin and its layers

4. Normal Body Temperatures
• Core temperature
• Shell (Skin) Temperature

5. Core temperature
• Temperature of the deep tissues and organs of
the body, including brain, heart, lungs,
abdominal organs.
• Average: between 98.0°F and 98.6°F when
measured orally.
• Remains very constant, within ±1°F , except
when a person develops a febrile illness.

6. Shell temperature
• Temperature of skin and muscles.
• Rises and falls with temperature of
surrounding.

7. Insulator System of the body
• Skin along with its subcutaneous tissues and
fat of subcutaneous tissue.
• Fat conducts heat only 1/3rd as readily as
other tissues.
• Helps maintain normal core temperature,
allows skin temperature to approach the
environmental temperature.

8. Blood flow to skin from body core
• Provides means of heat transfer
• High rate of blood flow Efficient transfer of
heat from core to the skin.
• Low rate of blood flow Decreased heat
conduction from core to skin.

9. Effect of change in environmental
temperature on heat conductance
• Degree of vasoconstriction is
controlled by the sympathetic
nervous system.
• Eight fold increase in heat
conductance between fully
vasoconstricted and
vasodilated state.

10. Mechanism of Heat loss from Skin
surface.

11. • Radiation: transfer of heat in the form of
infrared electromagnetic radiation from body
to other objects through the surrounding air.
• Conduction: Direct transfer of heat by contact.
• Evaporation: Insensible perspiration.

12. Mechanism of Sweating
• Sweat gland: a tubular structure consisting of
two parts:
1) a deep subdermal coiled portion that
secretes the sweat
2) a duct portion that passes outward through
the dermis and epidermis of the skin.

14. • Convection: First the heat is conducted to the
air surrounding the body and then carried
away by air currents.
• Panting: rapid shallow breathing, associated
with dribbling of more saliva (animals like
dogs which do not have sweat glands, heat is
lost by means of panting)

15. Regulation of Body Temperature
• Hypothalamus sets the normal range of body
temperature ( Set point: 37°C).
• Two centers that regulate body temperature:
1. Heat loss center
2. Heat gain center

16. • Heat loss centre: Preoptic nucleus of Anterior
Hypothalamus
• Heat gain centre: Posterior Hypothalamic
Nucleus

17. When body temperature rises:
2 major mechanisms:
1. Promotion of Heat Loss:
a. Vasodilation of skin blood vessels: caused by inhibition
of the sympathetic centers in the posterior
hypothalamus that cause vasoconstriction.
b. Sweating: sharp increase in the rate of evaporative heat
loss when the body core temperature rises above the
critical level of 37°C (98.6°F).
c. Relaxation of skeletal muscles: reduces heat production,
hair lies flat.

18. 2. Prevention of heat production
Shivering and chemical thermogenesis, are
strongly inhibited.

26. When body temperature falls:
• 2 major mechanisms:
1. Prevention of heat loss:
a. Skin vasoconstriction: by stimulation of the
posterior hypothalamic sympathetic centers.
b. Piloerection: means hairs “standing on end.”
Sympathetic stimulation causes the arrector
pili muscles attached to the hair follicles to
contract, which brings the hairs to an upright
stance.

27. 2. Promotion of heat production:
-Increase in thermogenesis (heat production).
-promoting shivering by contraction of skeletal
muscles

35. References
• Hall, J. E. 1. (2016). Guyton and Hall textbook
of medical physiology (12th edition).
Philadelphia, PA: Elsevier, Pg no. 889-895

36. THANK YOU!!!!