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HOMEOSTASIS. Thermoregulation. Louis Chow. What is it?. Significance?. Enables organisms to explore inhospitable environments. Homeostasis. The ability of the body to maintain a constant internal environment despite fluctuations in both the body’s activities and the external environment

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louis chow

HOMEOSTASIS

Thermoregulation

Louis Chow

homeostasis
What is it?

Significance?

Enables organisms to explore inhospitable environments

Homeostasis
  • The ability of the body to maintain a constant internal environment despite fluctuations in both the body’s activities and the external environment
  • Consists of specific values which are considered as normal
negative feedback mechanism1
Negative feedback mechanism
  • Receptors detects a stimulus (external or internal change).
  • Communication between the receptor and the effector(through a control centre).
  • Effector brings about the response to restore balance.
  • When the response is enough to return the body back to its normal state, the receptor is turned off.
why control body temperature
Why control body temperature?
  • Independence from changing environments
  • Affects the rate of metabolic reactions
  • Sensitivity of enzymes
ectotherms
Ectotherms

Ectotherms:

  • Fish, amphibians, reptiles etc.
  • Body temperature is greatly dependent on the external temperature
  • Variable metabolic rate
  • Activity levels determined by external environment
behavioral responses
Behavioral responses
  • Voluntary responses
  • Temperature too cold: cuddling, put on more clothes, eating, more muscular activities, move closer to heat sources, e.g the Sun
  • Temperature too hot: Less clothing, cool drinks, find shades, body orientation
endotherms
Endotherms

Endotherms:

  • Mammals and birds
  • Body temperature is less dependent on the external temperature
  • High metabolic rate
  • Possess thermoregulating mechanisms
physiological adaptions
Physiological adaptions
  • controlled by the thermoregulatory centre in the hypothalamus.
  • Receptors in the hypothalamus itself(blood temperature, the core temperature)
  • Skin receptors (the external temperature)
  • Also controlled by the cerebral cortex -- Voluntary actions
core temperature and skin temperature
Core temperature and skin temperature
  • http://www.youtube.com/watch?v=Vlp_NHuC0rw
thermoregulation
Thermoregulation

Hot:

Cold:

Increase heat gain

decrease heat loss

  • decrease heat gain
  • Increase heat loss
pilorelaxation and piloerection

Pilorelaxation and Piloerection

Relaxation of erector muscle Contraction of erector muscle

vasodilation and vasoconstriction
Vasodilation and Vasoconstriction

Hot:

Cold:

Skin arterioles constrict

Sphincter muscles contract

Shunt vessels dilate

Blood flow to skin capillaries decreased

  • Skin arterioles dilate
  • Sphincter muscles relax
  • Shunt vessels constrict
  • Blood flow to skin capillaries increased
sweat production
Sweat production

Hot:

Cold:

Inhibition of sweat glands

Decreased sweat production

  • Activation of sweat glands
  • Increased sweat production
extreme temperatures
Extreme temperatures

Hypothermia

Hyperthermia

Core temperature higher than 38.5 degrees Celsius

Adverse effects by drugs

Heat stroke

Dizziness, confusion

  • Core temperature falls below 35 degrees Celsius
  • Enhanced by alcoholic effects
  • Amnesia, death
preventing hypothermia
Preventing hypothermia
  • Wear more clothes!!
  • Avoid diving in cold water
  • Go closer to heat sources
preventing hyperthermia
Preventing hyperthermia
  • Find shades
  • Avoid excess exercise
what might come in the exam
What might come in the exam..
  • Where is the best place to take a temperature of a person?
  • Define evaporative heat loss.
  • Describe and explain a way of losing heat.
the end
THE END

Thank you!