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31 Cards in this Set
- Front
- Back
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Thermoreceptors in the hypothalamus and spinal cord are important for what?
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regulation of body temp (NOT conscious perception)
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What is temperature sensitivity based on?
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number and type of receptors present
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Where do you find the highest sensitivity to temperature?
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glabrous skin of the hand
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Where can you find the lowest temperature sensitivity?
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Back and back fo the leg
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Which receptors are more numerous (hot or cold)?
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Cold receptors
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True/False It is thought that the temperature receptors are directly affected by the physical effects of temperature and that is what controls the firing rate?
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FALSE( it is believed to be due to the effect of temperature on the metabolic rate of the receptor cell)
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Cold receptors fire maximally between temperatures of ?
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23-28 degree C
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What response will phasic firing of thermoreceptors have to decreasing temperature?
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ALWAYS increase in response to decreasing temp
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Is the tonic response to decreasing temp always increasing firing rate?
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no it can result in decreased firing rate depending on the initial temperature
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These receptors (warm or cold) are innervated by small, myelinated Adelta fibers?
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Cold receptors
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These receptors (warm or cold) are innervated by unmyelinated C fibers?
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Warm receptors
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Cold pain receptors begin firing at around what temperature ?
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15 degrees Celcius
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What happens to the cold-pain receptor as the skin becomes very cold and even frozen?
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Even the cold-pain receptor stops firing
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Heat pain receptors begin firing at what temperature?
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45 degrees C
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Is thermal stimuls localization very good or very poor?
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very poor (we use touch receptors to localize hot or cold objects)
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What controls body temperature by autonomic influence of body heat loss/production?
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Hypothalamus
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The body loses heat when the skin temperature is greater/lesser than the surroundings?
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Greater
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Irreversible damage occurs at approximately what temperature?
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42 degrees C
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This area of the brain is responsible for increasing heat production and conserving heat?
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Posterior Hypothalamus
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What are some ways to conserve heat?
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constriction of blood vessels and shivering
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What can occur in persons with a bilateral lesion of the posterior hypothalamus
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Poikilothermia
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What is the pathway involved with shivering?
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cold signals > dorsomedial portion of hypothalamus > AP to anterior horn motor neurons > Increase muscle tone > shivering
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The presence of this is important in maintaining body temperature in infants?
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brown fat
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Will cooling the peroptic area of the hypothalamus for several weeks result in an increase or decrease of thyroid hormone?
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Increase of thyroid hormone
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What is a set point?
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a temperature that does not require any thermoregulatory effector activity to maintain it
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What structure is responsible for heat dissipation and lowering the body temp?
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anterior hypothalamus
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A lesion in the anterior hypothalamus will result in what effect on thermal regulation?
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cannot dissipate heat >> HYPER thermia
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What are some ways the anterior hypothalamus regulates heat dissipation?
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vasodilation; cholinergic activation of sweat glands; inhibition of heat production mechanisms; behavioral modifications
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Vasoconstriction will conserve or dissipate heat?
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conserve
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What effect do pyrogens have on the hypothalamus?
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cause it to induce fever by the production of prostaglandins; elevate the set point
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Aspirin is beneficial to a fever because?
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it is anti-pyretic and can bind to hypothalamic cells to reduce fever
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