Temperature Regulation EQ How does our body regulate temperature?

Body Temperature Normal Body Temperature (NBT) – 98.60F(370C) Rectal Temp ----- (0.50F to 10F) above the Oral Rectal Temp reflects the internal body Temp (Core Body Temp) Core Body Temp remain almost constant Skin Temp (Shell Temp)-----Variable

Respiration Heat loss as the result respiratory vapor is exhaled

Radiation Thermal radiation is energy transfer by the emission of electromagnetic waves which carry energy away from the emitting object.

Evaporation Water on and in your skin turn to vapor

Convection Heat loss as the result of the movement of air or water surrounding

Conduction Heat loss as the result of direct contact with the skin

Role of Skin

Heat Exchange in the Skin

Vasoconstriction and Vasodilatation

Thermoregulation Temperature is regulated by nervous feedback mechanisms Thermoregulatory center located in the Hypothalamus Thermoregulatory regulatory responses include Autonomic Somatic Endocrine Behavioural changes

Feedback system 1) Receptor Sensor that responds to changes (stimuli) 2) Control Center Sets range of values Evaluates input and Sends output 3) Effector- Receives output from control center Produces a response

Body Temperature Control System Hypothalamus Acts as a thermostat Receives nerve impulses from cutaneous thermoreceptors Hypothalamus- also has thermoreceptors called central thermoreceptors These detect changes in blood temperature

Thermoregulatory regulatory responses Activated by Exposure to Cold Shivering Increase voluntary activity Increase TSH secretion Increase Catecholamines Vasoconstriction Horripilation Curling up

Thermoregulatory regulatory responses Activated by Exposure to Heat Vasodilatation Sweating Increase in Respiration Anorexia Apathy Decrease TSH secretion

Thermoregulatory regulatory responses Exposure to Cold Shivering Increase voluntary activity Increase TSH secretion Vasoconstriction Horripilation (erection of hairs) Curling up Exposure to Heat Vasodilatation Sweating Increase in Respiration Apathy Decrease TSH secretion

Hypothermia –Body temp below the normal lower limit (<970F) Contd---- Hypothermia –Body temp below the normal lower limit (<970F) Thermoregulatory responses Greatly impaired at (<940F) Lost at body temp(<850F)

Contd---- Frostbite Occurs at very low temp Common sites- Surface area freezes Ice crystals formed Common sites- Lobes of the ears Digits of hands Digits of feet Cold induced vasodilatation- Final protection against frostbite

Summary of Effector Mechanisms in Temperature Regulation

Left Side Activity Copy the mechanisms of heat loss (slide 3) and Summary of Effector Mechanisms in Temperature Regulation (slide 21) into your notebook