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36 Cards in this Set
- Front
- Back
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What types of lipids do we ingest?
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Triacylglycerol (90%)
Cholesterol Phospholipids Free Fatty Acids |
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Where is Lingual Lipase secreted & where is it activated?
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Lingual Lipase or Acid-Stable Lipase is Secreted in the Saliva and Activated in the Stomach
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Where is Gastric Lipase secreted & where is it activated?
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Gastric Lipase is Secreted in the Stomach and Activated in the Duodenum (at a neutral pH)
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What does Gastic Lipase primarily break down?
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Gastric Lipase acts on triacylglycerols w/short or medium length fatty acids (like milk)
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Why are fats not digested in the duodenum, even w/Lipases?
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Fats are not yet emulsified
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How does emulsification of lipids allow digestion?
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Emulsification increases surface area for digestive enzymes to act
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What are the Bile Acids?
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Cholic acid & Chenodeoxycholic acid
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Why can't Triglycerides just pass through the cell membranes?
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Triglycerides are lipid soluble, but too bulky to pass through mucosal cell membranes
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Where are bile salts produced?
Where are bile acids produced? |
Bile Salts are produced in the liver
Bile acids are the breakdown product of salts (made in the intestines) |
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How are Triglycerides broken down enough to be absorbed into the mucosal cell?
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Triglycerides will have two free fatty acids removed from C1 & C3, forming 2-monoacylglycerol. This is accomplished using pancreatic lipase
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How is the catabolism of cholesterol Esters accomplished?
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Cholesterol Esters are broken down by Pancreatic Cholesterol Esterase to form a cholesterol + 1 FFA
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How is catabolism of phospholipids accomplished?
(i.e. phosphatidylcholine) |
1. Phosphatidylcholine is broken down by phospholipase A2 (activated by trypsin)
2. Phosphatidylcholine loses 1 FFA and is broken down again by Lysophospholipase 3. End product is glycerophosphocholine |
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What are the primary products of lipid catabolism in the small intestine?
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FFA
Cholesterol 2-monoacyl glycerol |
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What happens to the fatty acids inside the mucosal cell when processing the lipids for transport to the body?
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1. Fatty acids are processed by Fatty Acyl CoA Synthase to produce Fatty Acyl CoA
2. 2 Fatty Acyl-CoA + 1 Monoacylglycerol are processed by Acyltransferase creating Triacylglycerol + 2 CoA Basically we broke down the triacylglycerol just to rebuild it again in the cell because it was too big to pass through the membrane |
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What is a family of enzymes that make triglycerides?
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Acyl Transferase
(they are specific from fatty acid chain length) |
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What protein binds free fatty acids in the blood to be transported?
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Albumin binds FFAs
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What do Acyl Transferases form when they add FFAs to Cholesterol or Lysophospholipids?
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Cholesterol Esters
Phospholipids |
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How are regenerated Triglycerides, Cholesterol Esters & Phospholipids allowed to circulate in the blood?
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The mucosal cells package the fatty acids by creating a Chylomicron
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What is the structure of a chylomicron?
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Triacylglycerols & Cholesterol Esters contained within a hydrophillic shell containing phospholipids and Apoproteins
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How do chylomicrons enter the blood?
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Chylomicrons are exocytosed and enter the lymphatic system via the intestinal lacteals. Then they enter circulation via the Left Subclavian Vein
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Where is Apoprotein synthesized?
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Apoprotein B-48 is synthesized in intestinal cells for incorporation into chylomicrons
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Where are the Triacylglycerols in chylomicrons destined for use?
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A. Skeletal Muscle (mostly)
B. Adipose Tissue (mostly) C. Heart D. Lung E. Kidney F. Liver |
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How does the chylomicron supply tissues?
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TG in chylomicrons is broken down by LIPOPROTEIN LIPASE, which turns TG into Glycerol + 3 FFAs
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What makes Lipoprotein Lipase?
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1. Lipoprotein Lipase is made and secreted by skeletal & adipose cells
2. It becomes bound to Luminal Membrane of Endothelial cells |
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What happens to glycerol after being created using Lipoprotein Lipase?
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The Glycerol is Used by the Liver for Glycolysis or Gluconeogenesis
(used to recreate triacylglycerol?) |
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What happens to the remnants of the chylomicron?
(cholesterol esters, phospholipid, apoprotein, and a little triglyceride) |
Remnants of chylomicron are taken up by the liver
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What happens to the FFAs once they are broken free by lipoprotein lipase?
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The FFAs may diffuse into neighboring cells or circulate bound to Albumin
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What are the supporting characteristics the Apolipoproteins provide Lipoproteins?
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1. Structure
2. Cell recognition 3. Lipoprotein metabolism |
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What are the primary functions of Chylomicrons?
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Donate FFAs to tissues
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What are the primary functions of VLDLs?
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Deliver Triglycerides from liver to tissues (actually the FFAs)
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What are the primary functions of LDLs?
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Deliver Cholesterol to tissues
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What are the primary functions of HDLs?
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Reservoir of APO CII for transfer to VLDL and chylomicrons (APO CII is needed to release the FFAs from TGs by adding Lipoprotein Lipase)
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What do HDLs do to cholesterol?
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HDLs scavenge cholesterol and trap it as cholesterol esters then transfer it to VLDL in exchange for TG and phospholipids. The HDL's are then endocytosed by liver and contents are recycled.
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What allows the chylomicron to exist in blood/water?
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Apolipoprotein B48
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What allows VLDLs to exist in blood/water?
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Apilipoprotein B100
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What is the function of VLDL?
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Deliver things that were made in the liver
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