Adipose
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- Describe the major structural and fxnal differences between white and brown fat
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White Fat: fxns as a long terms fuel reserve, provides insulation, and acts as mechanical cushion. some endocrine fxns. white adipose tissue is unilocular (1 fat droplet).
Brown fat: mainly in infants. fuel reserve, pathologic in adults. multilocular, rich mitochondria. - Describe the term "adipokines"
- Proteins secreted from adipocytes that have endocrine fxns.
- Describe the role of leptin in energy homeostasis
- it serves as a signal of energy sufficiency. Leptin levels rapidly decline with caloric restriction and weight loss. In contrast, common forms of obesity are characterized by elevated circulating leptin
- Understand factors that contribute to the complexity of adipose tissue
- adipose tissue has been identified as a major site for metabolism of sex steroid and production of adipsin, an endocrine factor that is markedly down regulated in obesity. Adipose tissue contains the metabolic machinery to permit communication with distant organs including the CNS.
- Describe the rold of leptin in energy homeostasis and in obesity
- Plasma leptin is positively correlated with body fat and mass. when a person is obese, they have high levels of leptin in their body, however it serves as a weak signal to the body. leptin maintains a minimal level of energy stores durin periods caloric restriction
- Explain the mechanism of tumor necrosis factor alpha induced weight loss and cachexia, & ID clinical conditions in which TNF contributes to weight loss
- TNF influences gene expression in adipose and liver. TNF represses genes involved in uptake and storage of fatty acids and glucose. in liver, TNF suppresses glucose uptake and metabolism. Higher Plasma levels of TNF are associated with insulin resistance, higher BMI, higher fasting glucose, and higher LDL's.
- For leptin describe: the site of synthesis, factors that regulate its expression, human leptin pathologies ID"ed
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1. made in adipose tissue, some in gastric mucosa.
2. Fat stores, fat size and fat cell number regulate leptin most.
3. Obesity, diabetes, cold intolerance, depressed immune fxn, infertility. - Estimate daily kilocalorie expenditure (REE):
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m: 66+(13.7xkg)+(5xcm)-(6.8xage)
f: 655+(9.7xkg)+(1.85xht)-(4.7xage) - Total energy expenditure
- TEE: 1.2-1.5 times REE
- Describe Pharmacologic tx to obesity
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Short term: Mazindol, diethylpropio, phenteramine, Benzphetamine, phendimetrazine, All CNS stimulants
Long term: Sibutramine (blocks NE,Se reuptake)
Orlistat: inhibits pancreatic lipase