lipid metabolism-adipose tissue metabolism

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LIPID METABOLISM- Fatty liver, Alcohol, Adipose Tissue metabolism:

LIPID METABOLISM- Fatty liver, Alcohol, Adipose Tissue metabolism Dr. Hariharan , V Assistant professor, Department of Biochemistry, Karpagam Faculty of Medical Sciences and Research, Coimbatore. Free ppt available in www.authorstream.com/ search drhari

At the end of this class you ll understand:

At the end of this class you ll understand Adipose tissue metabolism Regulation of fat mobilization in adipose tissue Brown Adipose tissue metabolism What is fatty liver and its pathogenesis Ethanol metabolism Free ppt available in www.authorstream.com/ search drhari

Adipose tissue:

Adipose tissue Stores fat(TAG). Either esterification (FFA + Glycerol TAG ) of lipolysis (TAG FFA + Glycerol) takes place Hormone sensitive Lipase digests TAG to FFA and glycerol Role of insulin Increases Glucose uptake in adipose tissue, PDH(Acetyl CoA ), Acetyl CoA carboxylase  FA and TAG synthesis Inhibits Hormone sensitive lipase Free ppt available in www.authorstream.com/ search drhari

Other regulatory factors:

Other regulatory factors Epinephrine, Nor epinephrine, glucagon, ACTH, MSH, TSH, GH Stimulate adenylate cyclase   cAMP + cAMP dependent protein Kinase +hormone sensitive lipase (TAGFFA + Glycerol)FFA level in blood increases Free ppt available in www.authorstream.com/ search drhari

Brown adipose tissue:

Brown adipose tissue It is involved in heat production ( thermogenesis ) Important for animals undergoing hibernation Well developed blood supply and lot of mitochondria per cell, but has low ATP synthase activity Free ppt available in www.authorstream.com/ search drhari

PowerPoint Presentation:

Norepinephrine   cAMP +lipoprotein lipase uptake of circulating lipoproteins into adipose tissue. Norepinephrine from sympathetic nerves   cAMP +lipase FFA FA undergoes beta oxidation Acetyl CoA Here oxidation is not coupled with phosphorylation  so no ATP produced from ETC and Ox phos  energy liberated as heat Free ppt available in www.authorstream.com/ search drhari

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Thermogenin acts as physiological uncoupler by increasing the permeability of H + into mitochondria, so the proton gradient is lost Free ppt available in www.authorstream.com/ search drhari H + ATP synthase ATP H + No ATP Heat released Mitochondria

Regulation of VLDL secretion:

Regulation of VLDL secretion Increased VLDL is produced by liver when Increased lipid uptake in diet Increased carbohydrate uptake-especially fructose and sucrose Increased FFA in circulation High insulin / glucagon ratio Ethanol ingestion Free ppt available in www.authorstream.com/ search drhari

Fatty liver:

Fatty liver Accumulation of TAG in liver leads to fatty liver Etiology Raised level of FFA Starvation, uncontrolled DM, high fat diet Metabolic block in production of lipoproteins Ethanol, Essential FA deficiency, CCl4, puromycin , choline deficiency Free ppt available in www.authorstream.com/ search drhari

I. Fatty liver due to increased Plasma FFA:

I. Fatty liver due to increased Plasma FFA In starvation, uncontrolled DM there is excess lipolysis from adipose tissue leading to increased plasma FFA. Also in high fat feeding there is excess FFA in plasma. Liver cannot handle all this FFA and convert them to VLDL. So TAG accumulates in the liver. Free ppt available in www.authorstream.com/ search drhari

II. Fatty liver due to block in lipoprotein production:

II. Fatty liver due to block in lipoprotein production This id due to deficient formation of VLDL from TAG in the liver. So TAG accumulates leading to Fatty liver Block in apolipoprotein synthesis- CCl4, puromycin Block synthesis of lipoprotein from apoprotein and lipid-CCl4 Failure in provision of phospholipids to form lipoproteins- Dietary EFA deficiency Failure in secretory mechanism- orotic acid Free ppt available in www.authorstream.com/ search drhari

PowerPoint Presentation:

Free ppt available in www.authorstream.com/ search drhari Adipose tissue Liver VLDL TAG TG FA Beta oxidation Ethanol TAG EFA Phospho lipid Secretion Orotic acid Translation Apoprotein Puromycin , CCl4 CCl4  FFA Starvation Uncontrolled DM High fat diet

Pathology :

Pathology Extensive accumulation of TAG leads to fatty liver Fat accumulation will lead to chronic fibrotic changes in liver This progresses to cirrhosis of liver if the cause of fatty liver not removed Free ppt available in www.authorstream.com/ search drhari

Lipotrophic factors :

Lipotrophic factors Some chemicals which prevent formation of fatty liver are called lipotrophic factors They are Choline Vitamin E Essential fatty acids Free ppt available in www.authorstream.com/ search drhari

Metabolism of ethanol (Alcohol):

Metabolism of ethanol (Alcohol) Ethanol is dehydrogenated to acetal dehyde . Acetaldehyde is dehydrogenated to acetic acid by aldehyde dehydrogenase The increased NADH produced competes with reducing equivalents from fatty acids leading to reduced oxidation of fatty acids  leading to their accumulation TAG production  fatty liver. Free ppt available in www.authorstream.com/ search drhari Ethanol Acetaldehyde Alcohol dehydrogenase NAD + NADH2

PowerPoint Presentation:

The increased NADH/NAD leads to reduced availability of NAD for Lactate dehydrogenase  lactic acidosis Lactic acidosis inhibits uric acid excretion aggrevates Gout Free ppt available in www.authorstream.com/ search drhari

Summary :

Summary Adipose tissue stores TAG. Insulin inhibits lipolysis and other hormones increase lipolysis Brown adipose tissue has thermogenin , which releases energy as heat. When more TAG accumulates in liver it leads to fatty liver Fatty liver may be due to increased FFA in blood or block in formation of VLDL in liver Lipotrophic factors protects against fatty liver Alcohol produces fatty liver and lactic acidosis Free ppt available in www.authorstream.com/ search drhari

References:

References Harper Free ppt available in www.authorstream.com/ search drhari

PowerPoint Presentation:

Free ppt available in www.authorstream.com/ search drhari Thank you

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