Term
| What coordinates heat production and reduction of heat loss when environmental temperatures are low? |
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Definition
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Term
| Describe thermogenic actions of thyroid hormone. |
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Definition
| Stim. Na/K ATPase and increase O2 consumption and metabolic rate. |
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Term
| Describe the effect of cold environmental temp. on activation of the symp. NS. |
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Definition
| Stim. of B2 receptors in brown fat to increase metabolic rate and heat. Stim of a1 receptors in cutaneous circ. causes vasoconstriction reducing heat loss. |
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Term
| What is the most potent mechanism for generating heat in the body? |
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Definition
| Shivering - rhythmic contraction of skeletal muscle (cold env. activates centers in the hypothalamus) |
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Term
| Increased body temp. __________ sympathetic activity in the skin blood vessels causing the shunting of blood to __________ _____________ near the skin surface. This is evidenced by _________. |
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Definition
| decreases, venous plexuses, red/warm skin |
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Term
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Definition
| Increased activity of symp. cholinergic fibers innervating sweat glands |
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Term
| What are foreign substances or chemicals that increase the hypothalmic set-point temperature to produce a fever? |
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Definition
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Term
| Describe the mechanism in which pyrogens produce a fever. |
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Definition
| Increased prod. of interleukin-1 (IL-1) in phagocytic cells. IL-q acts on the ant. hypothalamus to increase local prod. of prostaglandins which increase set-point temp. |
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Term
| What can be used to decrease the production of prostaglandins and therefore reduce a fever? |
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Definition
| Asprin and other cyclooxygenase inhibitors |
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Term
| What occurs during heat exhaustion? |
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Definition
| Excessive sweating resulting in decreased ECF, blood volume, and arterial pressure, and fainting |
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Term
| When does heat stroke occur? |
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Definition
| When body temp. increases to the point of tissue damage, may occur if sweating is impaired as in dehydration |
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Term
| What is malignant hyperthermia? |
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Definition
| Massive increase in metabolic rate, O2 consumption, and skeletal mus. heat production |
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Term
| what can cause malignant hyperthermia? |
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Definition
| Inhalation anesthetics, genetic susceptibility (ryanodine receptor) |
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