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Thermoregulation - PowerPoint PPT Presentation


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Thermoregulation. GROUP STARTER: WHAT’S THE LINK???. How would your body change in these environments?. When we feel hot…. When we are cold…. We need to lose heat faster as our core body temperature is in danger of rising and becoming too hot (>37 °C) .

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Presentation Transcript
when we are cold

When we feel hot…

When we are cold…

We need to lose heat faster as our core body temperature is in danger of rising and becoming too hot (>37°C).

We need to warm up faster as our core body temperature is in danger of becoming too cold (<37°C).

slide6

DEATH from HYPERTHERMIA

420C

390C

370C

350C

330C

280C

250C

Dehydration and heat stroke

Unusual sweating, fever

NORMAL

Shivering

Difficulty in staying awake

Breathing stops

DEATH from HYPOTHERMIA

as we got through the next few slides
As we got through the next few slides….
  • Try and fill in your worksheet!
role of hypothalamus
Role of Hypothalamus
  • Acts as a thermostat
  • Sensitive to nerve impulses
  • Received from hot and cold thermoreceptors in the skin
  • Hypothalamus also possesses central thermoreceptors

-sensitive to changes in temperature of blood

-these reflect changes in temperature of body core

thermo regulatory centre in the brain
Thermo-regulatory centre in the brain
  • Responds to information
  • Sends appropriate nerve impulses to effectors
  • These trigger corrective feedback mechanisms
  • Return body temperature to normal level (set point)
role of skin
Role of skin
  • Leading role in temperature regulation
  • Responds to nerve impulses from the hypothalamus
  • Skin acts as an effector
involuntary responses
Involuntary responses
  • Mechanisms of temperature regulation are involuntary
  • Controlled at a subconscious level by the hypothalamus
vasodilation
Vasodilation
  • Skin becomes dilated
  • Large volume of blood flows through capillaries near skin surface
  • Blood able to lose heat by radiation
increase in rate of sweating
Increase in rate of sweating
  • Heart energy from body
  • Convert sweat into water vapour
  • Lowers body temperature
vasoconstriction
Vasoconstriction
  • Arterioles leading to skin become constricted
  • Small volume of blood flow to surface capillaries
  • Little heat lost by radiation
slide15

This means less heat is lost from the surface of the skin

If the temperature falls, the blood vessel constricts (gets shut off).

decreased rate of sweating
Decreased rate of sweating
  • Sweating reduced to a minimum
  • Heat conserved
contraction of erector muscles
Contraction of erector muscles
  • Wide layer of air trapped between body and external environment
  • Air poor conductor of heat
  • Layer of insulation reduces heat loss
voluntary responses
Voluntary responses
  • Body temperature drops below normal
  • Nerve impulses transmit this information to cerebrum
  • Person ‘feels cold’
  • Takes appropriate action to correct problem

-puts on a jacket

-has a cup of tea etc.