HOMEOSTASIS

Homeostasis – Remember it! & Test it!

Homeostasis – Remember it! & Test it!

  • Homeostasis is how your internal body is able to stay at in an almost constant state.
  • Body temperature is controlled by homeostasis.
  • Endotherms (mammals and birds) create their own heat. Ectotherms (other animals) rely on their surroundings for heat.
  • The main advantage of being an endotherm is that they can live in nearly all habitats but they require a large amount of energy.
  • Temperature homeostasis in humans is controlled by two thermoregulatory centres which are located in the hypothalamus.
  • Thermoreceptors are located on the hypothalamus and in the skin.
  • The thermoregulatory system makes up part of the autonomic nervous system.
  • Ectotherms rely on thermoregulatory behaviour.
  • The main advantage of being an ectotherm is that they don’t use and therefore don’t need as much energy as endotherms but they move more slowly at certain times of the day.
  • All animal cells within the body are affected by its level of concentration in the blood.
  • Blood glucose is controlled by the Islets of Langerhans located in pancreas.
  • ? cells secrete glucagon in response to a low blood glucose concentration and ? cells secrete insulin in response to a high blood glucose concentration.
  • Adrenaline also plays an important role in stimulating the liver to release glucose.
  • All three hormones involved use second messengers.
  • Diabetes is a disease caused by glucose homeostasis not functioning properly.
  • The disease can be controlled with insulin injection and a strict diet.

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TEST IT!

  1. Desert Horned Lizards live in the deserts in Idaho. A group of biologists measured the oxygen consumption of these lizards at different body temperatures. The results they measured are in the table below.

    Body temperature (