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13 Cards in this Set
- Front
- Back
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What effect does electrical stimulation of the ventromedial hypothalamus have on feeding? What effect do lesions in this area have?
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Stimulation supresses food intake, whereas lesions cause uncontrolled eating.
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What effect does electrical stimulation of the lateral hypothalamus have on feeding? What effect do lesions in this area have?
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Stimulation causes uncontrolled eating, whereas lesions result in anorexia.
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How does injection of CCK affect eating behavior? How does this affect long-term weight?
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It provides inhibitory signals which cause cessation of eating. This is a transient effect and does not change weight over time. Caloric intake remains constant because although meals are smaller, they are more frequent and more numerous.
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Describe the effect of injection of exogenous ghrelin.
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It provides a transient appetite stimulation and increased intake of food.
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Do serum levels of endogenous ghrelin remain constant in the blood? How do the levels of ghrelin in obese persons compare to those of normal persons?
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Ghrelin levels rise and fall in a cyclic manner related to timing of meals. In obese persons, ghrelin levels are actually lower than normal.
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What are 3 pieces of evidence for the existence of a set point of body weight?
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1.Body weight does not change more than 1-2 lbs/year.
2.Identical twins maintain similar weight, even if they are separated. 3.There are numerous hereditary obesity diseases. |
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Increase in mass of adipose tissue is thought to provide a signal to the CNS which then effects a decrease in tissue mass. What is the effector mechanism here?
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The CNS stimulates diet-induced thermogenesis which speeds metabolic rate through sympathetic innervation to reduce the mass of adipose tissue.
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What gene codes for leptin? In what tissue is this gene expressed? What evidence exists that leptin is a secreted compound?
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*the obese gene
*expressed in adipose tissue *has a signal peptide |
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What happens when obese mice are injected with exogenous leptin?
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They lose adipose tissue (not lean mass) due to decreased intake and increased metabolic rate.
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How is leptin connected to amenorrhea in female athletes?
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Female athletes have less adipose tissue, thus secrete less leptin. Leptin is thought to have a stimulatory role in the secretion of estrogen. Low leptin means low estrogen and thus amenorrhea.
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What is the blood level of leptin in obese persons? What does this mean?
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Most obese persons show an excess of functional leptin. In only a few isolated cases has obesity been associated with leptin deficiency. This has led to the idea that obesity is associated leptin resistance.
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What is the protein product of the "diabetes" gene? Where is this gene expressed?
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This gene codes for the leptin receptor. It is expressed in the ventromedial area of the hypothalamus.
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What happens when a db/db mouse is parabiotically attached to an ob/ob mouse?
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The ob/ob mouse loses weight because it receives leptin from the db/db mouse. The db/db mouse remains obese.
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