- What is homeostasis?
(Mechanisms of) control and maintenance of a constant internal environment regardless of the external conditions; - Name any three factors that must be maintained constant in mammalian bodies
Temperature; Water; Salt or ion content; Carbon (IV) oxide; Glucose; amino acids; - Explain how endotherms respond to heat and cold conditions in their environment
Heat/hot conditions:
Increased sweating; to lose heat through latent heat of vaporization;
Dilation of arterioles under the skin; to bring more blood to the skin surface to lose heat to the atmosphere;
Decreased body metabolism; to reduce heat generation;
Erector pili muscles relax; making hair follicles to relax hence hair lies flat on skin, no air is trapped; to lose heat;
Slow/reduced muscular activity due to slow metabolism; to reduce heat production;
Panting to expose tongue and mouth; to release heat;
Moving to shades to avoid direct heat;
Aestivation; to escape the extreme heat; flapping of ears to create currents to carry away heat;Cold conditions:
Stamping of feet; to generate heat;
Basking in the sun to gain heat directly;
Less production of sweat; to reduce water loss through latent heat of vaporization;
Vasoconstriction of arterioles; hence less blood flow to the skin surface to reduce heat loss;
increased metabolism through release of more thyroxine hormone; to generate heat;
Erector pili muscles contract; pulling hair follicles hence hair is raised; to trap a layer of moist air; to prevent heat loss;
shivering/rapid contraction of muscles; to yield heat to warm body;
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