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59 Cards in this Set
- Front
- Back
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Lipids
-define |
-soluble organic solvents
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Lipids found in animals
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-Sterols (cholesterol)
-Glycerol esters (triglycerides) -Fatty acids -Sphingosenes -Terpenes (Vits A, E, K) |
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Lipoproteins
-define |
-how cholesterol and triglycerides are transported in serum
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Lipoprotein types
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-chylomicron
-Very Low Density Lipoprotein (VLDL) -Intermediate Density Lipoprotein (IDL) -Low Density Lipoprotein (LDL) -High Density Lipoprotein (HDL) |
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Chylomicron
-major lipid -site of formation -major site of degredation |
-lipid: dietary TG
-site of formation: small intestine enterocyte -degredation: plasma and hepatocytes |
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VLDL
-major lipid -major site of formation -major site of degredation |
-lipid: Hepatic TG
-site of formation: hepatocyte -degredation: plasma |
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IDL
-major lipid -major site of formation -major site of degredation |
-lipid: hepatic TG & cholesterol ester
-site of formation: plasma -site of degredation: plasma |
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LDL
-major lipid -major site of formation -major site of degredation |
-lipid: phospholipid & cholesterol ester
-formation: plasma -degredation: hepatocytes |
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HDL
-major lipid -major sites of formation -major sites of degredation |
-lipid: phospholipid & cholesterol ester
-formation: hepatocyte -degredation: hepatocyte |
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Lipoproteins that contribute to serum lactescence
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-chylomicron
-VLDL |
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Major processes that affect [lipoprotein]
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-production (of chylomicrons in enterocytes and VLDL in hepatocytes)
-IV processing (LPL catalysed lipolysis on endothelial cell membranes) -Clearance (hepatocyte) |
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Lipoprotein lipase
-function -requirement |
-function: breaks down triglycerides into fatty acids
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Lipoprotein metabolism (Postprandial)
-describe |
-ingested TGs in the presence of LPS and bile acids undergoes lipolysis to form Monoglyceride & Fatty Acid
-MG & FA are reabsorbed by enterocytes and reformed into TG -Enterocytes assemble TG, CE, phospholipid and apolipoproteins into chylomicrons -Chylomicrons enter blood via thoracic duct -With Insulin LPL is activated converting TG into FA for adipocytes or muscle -Remnant of chylomicron is then removed from the plasma by hepatocytes |
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Lipoprotein metabolism (Endogenous)
-describe VLDL |
-VLDL assembled in hepatocytes
-secreted into sinusoidal blood -with insulin, LPL is activated converting TG into FA -VLDL becoms denser as TG is lost --> IDL --> LDL -LDL delivers cholesterol to many cells for cell membranes or steroid synthesis -LDL either ends up in cells or is removed by macrophages in liver |
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HDL function
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-serve as apolipoprotein source for other lipoproteins
-accept cholesterol from plasma membranes/lipoproteins and transport it for reutilization or degredation |
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Triglyceride-rich lipoproteins
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-Chylomicron
-VLDL |
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Cholesterol-rich lipoprotein
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-HDL
-LDL |
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Fate of cholesterol after returned to hepatocytes
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-reused in new lipoproteins
-excreted in bile -degraded to bile acids |
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Triglyceride
-production in monogastrics |
-fasting = hepatocytes
-postprandial = enterocytes |
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Triglyceride
-production in ruminants |
-always producing
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TG uses
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-tissue/muscle = energy
-adipocytes = storage |
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Hyperlipemia
-define |
-inc. [lipid] in blood
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Hyperlipidemia
-define |
-inc. [lipid] in blood
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Hyperlipoproteinemia
-define |
-inc. concentration of lipoproteins in blood
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Lipemia
-define |
-used to define the turbid or opaque appearance of serum (lactescence)
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Hyperlipidemia
-classifications |
-physiologic (postprandial)
-Primary (congenital; hereditary) -Secondary ( acquired) |
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Physiologic hyperlipidemia
-effect in dogs and cats |
-inc. chylomicrons
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Physiologic hyperlipidemia
-time for chylomicron clearance in Cats and Dogs |
-8-16 hrs
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Physiologic hyperlipidemia
-what to think of when there is delayed clearing in cats and dogs |
-secondary hyperlipidemia
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Pathologic states of hyperlipidemia
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-defective clearing by hepatocytes
-defective lipolysis (IV) -excessive VLDL production -hormone sensative lipase causing TG--> FA |
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Hormonal influences causing TG--> FA
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-Glucagon
-Epinephrine -Cortisol -Insulin (-) |
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Primary hyperlipidemia
-what is it -seen in -cause |
-congenital or hereditary defect
-seen in Miniature Schnauzers -cause: dec. production of LPL --> defective lipoprotein lipolysis |
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Secondary Hyperlipidemia
-causes (most common*) |
-Hypothyroidism (*)
-Diabetes mellitus (*) -Acute pancreatitis -Cholestasis -Hyperadrenocorticism -Nephrotic Syndrome & PLN -Equine hyperlipemia (*) - |
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Hyperlipidemia caused by hypothyroidism
-what is expected to increase -reasons why |
-inc. cholesterol
why: -dec. hepatic lipase ---> dec. clearance of LDL -dec. thyroxine --> dec. LPL activity |
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Hyperlipidemia caused by diabetes mellitus
-what is expected to increase -reasons why |
-inc. TG
why: -dec. insulin --> dec. LPL activity -inc. VLDL synthesis from influx of FAs |
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Hyperlipidemia caused by Acute Pancreatitis
-what is expected to increase -reasons why |
-Inc. TG
why: -dec. insulin --> dec. LPL activity -inflammatory cytokines -cholestasis |
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Hyperlipidemia caused by cholestasis
-what is expected to increase -reasons why |
-inc. cholesterol
why: -dec. cholesterol biliary excretion -effector --> inc. cholesterol synthesis |
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Hyperlipidemia caused by hyperadrenocorticism
-what is expected to increase -reasons why |
- inc. cholesterol
why: -stimulation of VLDL synthesis -inc. hormone sensitive lipase --> inc. FA reflux -antagonize insulin --> dec. LPL activity |
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Hyperlipidemia caused by Nephrotic Syndrome & PLN
-what is expected to increase -reasons why |
-inc. cholesterol
why: -stimulate VLDL synthesis in hepatocytes -dec. intravascular processing |
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Hyperlipidemia caused by Equine Hyperlipemia
-what is expected to increase -reasons why |
-inc. TG
why: -anorexia, obesity, pregnancy, lactation, renal failure, endotoxemia -neg. energy balance --> mobilization of FAs --> inc. synthesis in hepatocytes --> inc. VLDL |
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Hyperthyroidism causing hyperlipidemia
-pathogenesis |
Dec. triiodothyronine (T3)
-dec. hepatic lipase activity --dec. clearance of LDLs ---hypercholesterolemia Dec. Thyroxine (T4) -dec. LPL activity --dec. intravascular processing (possible mild inc. in [TG]) ---hypercholesterolemia |
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Nephrotic syndrome causing hyperlipidemia
-pathogenesis |
-dec. Lipolysis of lipoproteins with apoprotein B
--hyperlipoproteinemia (hypercholesterolemia) Possibly linked to PLN causing a loss of protein to bind to LPL |
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Postprandial cause of hyperlipidemia
-pathogenesis |
Ingest a TG containing meal
-inc. formation of chylomicrons --chylomicrons enter lacteals ---chylomicrons enter blood ----hypertriglyceridemia |
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Main reason for delayed clearing of chylomicrons
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-any condition with dec. LPL activity
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Diabetes Mellitus causing hyperlipidemia
-pathogenesis |
Insulin deficiency
-dec. LPL activity --dec. intravascular lipolysis ---hyperlipoproteinemia (hypertriglyceridemia, hypercholesterolemia) -inc. mobilization of feuls --inc. production of VLDLs ---hyperlipoproteinemia (hypertriglyceridemia) |
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Pancreatitis causing hyperlipidemia
-pathogenesis |
-dec. insulin ---> dec. LPL
-inc. TNF --inc. production of VLDLs |
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Equine hyperlipidemia causing hyperlipemia
-pathogenesis |
Anorexia, Pregnancy, Lactation, Renal Failure, dec. Insulin...
-neg. energy status --inc. glucagon ---inc. lipolysis of TG in adipocytes ----inc. FAs to liver -----inc. TG synthesis in liver ------inc. VLDL production -------hyperlipidemia (inc. TG) |
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Causes of secondary hyperlipidemia that can result in Lipemia
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-Postprandial
-Diabetes mellitus -Pancreatitis -Equine hyperlipidemia |
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Portosystemic shunt/Liver failure causing hypolipidemia
-pathogenesis |
Dec. functional hepatic mass
-dec. production of cholesterol, TG, apoproteins, phospholipids --dec. production of VLDLs ---dec. plasma lipoproteins ----hypocholesterolemia |
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Hypercholesterolemia
-causes |
-inc. cholesterol production
-dec. lipolysis of intravascular processing of lipoproteins -unknown/multiple mechanisms |
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Inc. cholesterol production
-caused by |
-by hepatocytes due to nephrotic syndrome or PLN
-by enterocytes due to postprandial hyperlipidemia |
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Dec. lipolysis of intravascular processing of lipoproteins
-causes |
-hypothyroidism
-Nephrotic syndrome or PLN |
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Unknown mechanisms causing hypercholesterolemia
-causes |
-obstructive cholestasis
-diabetes mellitus |
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Hypertriglyceridemia
-causes |
-inc. triglyceride production
-dec. lipolysis or intravascular processing of lipoproteins -unknown/multiple mechanisms |
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Inc. triglyceride production
-causes |
-by hepatocytes due to Equine hyperlipemia/hyperlipidemia
-by enterocytes due to postprandial hyperlipidemia |
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Unknown mechanisms causing hypertriglyceridemia
-causes |
-acute pancreatitis
-daibetes mellitus |
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TG & Cholesterol in chylous effusion compared to plasma
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-TG: inc.
-Cholesterol: ok-inc. -Chol:TG : dec. |
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Standing plasma test for chylomicrons
-describe |
Visual lipemia when the plasma stands for 16 hrs
-creamy layer on top --> chylomicrons -creamy layer not present --> chylomicrons are or are not present |
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Cholesterol lowering drugs in humans
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-bile acid sequestrants
-statins -inhibit pancreatic lipase -inhibit cholesterol absorption |
