Ch44_Excretory_System

Ch44_Excretory_System - Chapter 44 Regulating the Internal...

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Chapter 44 Regulating the Internal Environment Bill Catherine Jane
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Homeostasis is the ability of animals to regulate their internal environment The three main aspect of homeostasis are thermoregulation, osmoregulation, and excretion. Animals often maintain homeostasis by being regulators or conformers. Regulators are animals who use internal mechanisms to moderate internal changes.
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Conformers allow conditions in their bodies to change with external conditions. An organism may be a conformer to one condition but a regulator for another. The picture of the lizard basking in the sun demonstrates conforming.
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Regulating Body Temperature (Thermoregulation) Enzyme-mediated reactions generally increase by a factor of 2-3 for every 10 degree increase in temperature until it denatures the protein. This is known as the Q10 effect , where Q10 is the rate of reaction increase. Temperature also affects the power and speed of muscle contractions.
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The 4 physical processes of heat gain and loss Conduction is the direct transfer of heat from two objects coming into contact with each other. Convection is caused by the movement of air or liquid past a surface. Radiation is the transfer of heat through electromagnetic waves. No contact is needed. Evaporation is the loss of heat due to the transformation of liquid to a gas.
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Ectotherms have low metabolic rates and are very effected by the temperature of their environments. Endotherms have high metabolic rates that keep their bodies much warmer than the surrounding environment. Endotherms can do vigorous activity for long times because of their metabolism, but also need to eat more than ectotherms. This Lesser tree shrew is an example of an endotherm
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Physiological and behavioral adjustments also help to regulate temperature. Animals can have adaptations to adjust the rate of heat exchange with the environment including a layer of insulation to lessen heat transfer such as fur, feathers, and fat as well as adaptations to the circulatory system. Walrus have a layer of blubber that helps to insulate them from the cold water and ice in which they live
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Vasodilation is the increase in the diameter of superficial blood vessels and is often accompanied by increased blood flow to the skin to help cool the animal. Vasoconstriction is the opposite of vasodilation and helps to prevent heat loss by directing blood to the core of the body and the vital organs.
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Countercurrent heat exchange Countercurrent heat exchange is vital in many animals that face the problem of losing a lot of heat from their extremities. The warmer blood from arteries flowing to the limbs is kept deep on the inside of the limb while the colder blood in the veins travel back to the body. The heat from the arteries warms the returning blood more
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Ch44_Excretory_System - Chapter 44 Regulating the Internal...

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