Homeostasis in mammals flashcards

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What is homeostasis?

The maintenance of a constant internal environment (e.g., temperature, pH, glucose concentration) within narrow limits, despite changes in external or internal conditions.

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Describe the principle of negative feedback.

A corrective mechanism where a change from a set point triggers a response that opposes the initial change, restoring the system to its normal level. It is the primary mechanism for homeostasis.

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What is the role of the hypothalamus in thermoregulation?

It acts as the body's thermostat. It contains thermoreceptors that monitor blood temperature and it coordinates corrective physiological and behavioural responses to maintain core temperature at approximately 37°C.

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How does vasodilation help cool the body?

Arterioles supplying skin capillaries widen (dilate), increasing blood flow to the skin surface. This enhances heat loss to the environment via radiation and convection.

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What hormone is released when blood water potential is low, and what is its effect?

Antidiuretic hormone (ADH) is released from the posterior pituitary gland. It increases the permeability of the collecting ducts and distal convoluted tubules in the kidney to water, increasing water reabsorption into the blood.

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Which cells secrete insulin, and what is its primary function?

Beta (β) cells in the Islets of Langerhans (in the pancreas) secrete insulin. Its function is to lower high blood glucose by increasing glucose uptake by cells and promoting its conversion to glycogen for storage.

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Which hormone counteracts the effect of insulin, and how?

Glucagon, secreted by alpha (α) cells in the pancreas. It raises low blood glucose by stimulating glycogenolysis (breakdown of glycogen to glucose) and gluconeogenesis (synthesis of glucose) in the liver.

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Define osmoregulation.

The homeostatic control of the water potential of the blood and body fluids, primarily carried out by the kidneys under the influence of ADH.