Term
| What compound is the primary product from the small intestinal reaction of pancreatic lipase and bile salts on ingested triacylglycerol? |
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Definition
2-monoacylglycerol
forms 70% of lipid digestion product
[image] |
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Term
| Identify and quantify the three sources of lipase production? |
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Definition
lingual lipase (negligible)
gastric lipase (10-30%)
pancreatic lipase (50-70%) |
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Term
Where is chylomicron?
What is chylomicron?
Why is chylomicron? |
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Definition
Where: Produced inside the enterocyte/intestinal epithelium/brush border from absorbed components of broken down mixed micelles (EX: futile cycle); released into lymph circulation (lacteals) and travels to blood circulation (enters at junction of left subclavian vein and internal jugular veins)
What: Micellar constituents are processed into triacylglycerol, fatty acyl-CoA, and cholesterol ester; these are combined with protein and phospholipid to form these large lipoprotein structures
Why: This form is easy to transport, a polar/hydrophilic exterior and highly polar/hydrophobic interior. "Think oil drop coated with a protein skin." It carries lipids through lymph and blood to adipocytes for storage; muscle, liver cells for energy and/or storage. |
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Term
When lipid and bile acid concentrations reach a specific threshold these structures spontaneously form.
What is this threshold named? |
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Definition
Micelles: fat droplet<emulsion<micelle
Each one is increasingly: orderly, transportable, and its contents accessible to receptors/enzymatic action
Critical micellar concentration (CMC)
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Term
| Describe the structure of bile salts and their importance in lipid digestion. |
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Definition
Bile salts are composed primarily of cholic acid (amphipathic molecule=polar end loves water, nonpolar end hates water). This provides a "detergent action" which facilitates transport and lipase access. Bile salts can conjugate with taurine/lysine to form taurocholate/glycocholate, which makes it more polar.
[image] |
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Term
| What enzymes and lipids are involved in enterocellular lipid processing, leading to chylomicron formation? |
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Definition
[image]
Exception: Medium chain triglycerides do not travel in chylomicrons though the lymph. MCT's go directly to the liver via the portal circulation. |
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Term
| There is an inverse relationship between lipoprotein diameter and buoyant density. Sort the lipoproteins we know from smallest/most dense to largest/least dense based on this fact. |
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Definition
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Term
| A lymphatic chylomicron in the thoracic duct will be composed of a higher or lower percentage of cholesterol than a chylomicron in an artery immediate to the liver? |
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Definition
LOWER PERCENTAGE OF CHOLESTEROL
At target sites, lipoprotein lipase (enzyme captive to capillary endothelium) breaks off lipids/triglycerides, "deflating the chylomicron balloon" as it passes along vessels. This results in cholesterol ester rich proteinaceous chylomicron remnants at the liver.
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Term
| A patient has a defect in genes that code for lipoproteins and it is determined that there is inadequate Apo C-II production. What abnormal lab value would be expected? |
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Definition
High plasma triglyceride
This would also be the case with low lipoprotein lipase levels. In this case, triacylglycerol can not be removed from their chylomicron carriers and will remain in the blood. |
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Term
The pathophysiology of lipid digestion is classified into four types. List, define, and give examples of them.
If a patient has one of these disorders, what clinical finding would present? |
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Definition
1. Luminal Digestion: Defects in pancreatic enzyme synthesis and secretion.
(Cystic fibrosis or chronic pancreatitis)
2. Luminal Transport: Bile acid deficiency due to interrupted enterohepatic circulation, ileal resection or dysfunction, or biliary obstruction.
(Gallstones, deconjugation of bile acids, bacterial overgrowth syndrome)
3. Mucosal Cell Transport: Inadequate chylomicron formation.
(beta-lipoproteinemia/hypo-betalipoteinemia)
4. Lymphatic Transport: blockage.
(Congenital lymphangiectasis, Whipple's disease)
Steatorrhea-fatty diarrhea (Greek: "fat" "stream") |
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Term
| For chylomicrons, LDL, VLDL, and HDL: list the constituents and percentages in each type. |
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Definition
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