Thermoregulation

Vocab:

  • Thermoregulation → maintaining internal temperature by negative feedback mechanisms

  • Endotherm → animal that maintains its temperature through internal mechanisms

  • Ectotherm → animal that maintains its temperature by absorbing thermal heat from external environments (ex. sun, warm places)

  • Poikilotherms → can survive at wide range of temperatures

  • Homeotherms → need a very specific range of temperature to survive

  • Thermoreceptors → the sensor of heat in skin

  • Hypothalamus → part of brain that regulates temperature

  • Vasoconstriction → constricting blood vessels

  • Vasodilation → dilatation of blood vessels

  • Torpor → a sleep like state where body reduces amount energy used makes the heart rate drop and body temp drops

  • Thermal Acclimatization → seasonal adjustments to survive the weather

  • Hibernation estivation ???→ a state of torpor that enables an animal to survive the summer by reducing the demand for energy

Endotherms

Ectotherms

regulate temperature through metabolic processes (Physiological) and behaviours

produce their own heat

regulate body temperature through behaviour ONLY

eg. mo nhuving between shade and sun

rely on heat from environment = move environment throughout day/night

Are typically homeotherms → have specific range of temp. they can survive in

eg. lizards regulate temp by behaviour, but survive in specific range of temp

Can be both homeotherms or poikilotherms

have more mitochondria

Poikilotherms

Homeotherms

can survive at wide range of temperatures

allow body temp to fluctuate

need a fairly consistent body temperature to survive

keep body temp constant

Behavioural Mechanisms for thermoregulation

  • ectotherms regulate temp by moving throughout day/ night

    • cold water fish move up and down through thermal layers as needed

    • lizards move between sun and shade

Physiological mechanism for thermoregulation

  • Body Temp decreases and blood is cooler than set point

    • heat promoting center in the hypothalamus is activated

      Effector:

      • Skeletal muscles begging shivering = heat due to friction

      • Skin blood cells constrict = blood withdrawing from skin and going to deep tissues → this minimizes heat loss from skin surface

  • Body Temp Increases and blood is warmer than set point

    • heat-loss center in hypothalamus is activated

      Effector:

      • Sweat glands activate → release sweat, which the body heats up and turns into vapour, helping in body cooling

      • Skin blood vessels dilate = blood is pushed out to capillaries and heat radiates off skin surface

  • Vasodilation = too hot = blood sent towards skin

  • Vasoconstriction = too cold = blood sent away from the skin and kept among organs