cholesterol
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- What are the dietary sources of Cholesterol?
-
High cholesterol: Organ meats, eggs.
Moderate cholesterol: Meats, milk
products with medium to high fat
content.
Low cholesterol: Milk products with
low fat content.
Very low cholesterol: Skim milk
products.
No cholesterol: Plant foods. - What are the endogenous sources of Cholesterol?
- Liver, intestine, adrenal cortex and reproductive tissues.
-
What is the rate-limiting step in Cholesterol synthesis?
HMG CoA is turned into __________ by _________ whose expression is limited by cholesterol. -
Mevalonic Acid
HMG CoA reductase - Smith-Lemli-Opitz syndrome (SLOS) is a Autosomal recessive condition caused by deficiency of ___________
- 7-dehydrocholesterol-7-reductase
-
Smith-Lemli-Opitz syndrome (SLOS) is characterized by the following:
Etiology discovered 1993
Congenital Malformations
Low plasma cholesterol
_______ 7 DHC (precursor)
_______ 7 DHCR (enzyme) -
Increased
Decreased - Cholesterol synthesis is regulated by the ___________ gene and the __________ binding to the gene
-
sterol regulatory element (SRE)
sterol regulatory binding protien (SRBP) - cholesterol-lowering drugs like statins reduce Cholesterol synthesis by acting as an anolog of _________ that can not be converted to ___________
-
HMGCoA
Mevalonic Acid - one of the functions of Cholesterol is to make _________ which is used to make vit A, E, & K
- isopentyl pyrophosphate
- Cholesterol is also used to make vitamen __
- D
- cholesterol is also used to make ________,________, & _______
- cholesteryl esters, membranes & plasma lipoprotiens, & bile acids
- 7-dehydrocholesterol is converted in the ______ by UV light into ___________
- Cholecalciferol (vit D3)
- Cholecalciferol (vit D3)is converted in the _______ by 25 hydroxylase into _________
-
liver
25-hydroxycholecalciferol - 25-hydroxycholecalciferol is converted in the _______ by 1 alpha hydroxylase into _____
-
Kidney
1,25 DHCC - Cholesterol is modified to make two sets of bile acids with the addition of ______ & _______
- taurine & glycine
- the mnemonic "PVT TIM HALL always Argues, never Tires".
-
Phenylalanine
Valine
Tryptophan
Threonine
Isoleucine
Methionine
Histidine
Arginine
Lysine
Leucine
always argenine never tiresine - bile acids form fats by forming a ______
- mycell
-
How do bile acid sequestrant drugs reduce blood Cholesterol?
Bile acids are made in liver. They are then sent to the gall bladder to store. After eating a fatty meal bile acids get sent to the intestine where they form mycells capture the fatt - excretion
- Cholesterol makes up ________, & ________ carry cholesterol.
-
plasma lipoproteins
plasma lipoproteins - Chylomicron is a type of _________
- plasma lipoproteins
- Describe the structure of cholesterol.
- Chol is 4 ringed C molecule that has C tail
- Identify the dietary and endogenous sources of cholesterol
- Dietary: Eggs, milks, meats --- endogenous: liver what tissue types?
- Identify the substrate-product-enzyme of the rate limiting step of cholesterol synthesis.
- HMG Co A (substrate) turned into Melamalonic acid (product) by the enzyme HMG Co A reductase (RLS)
- Identify the enzyme deficiency in Smith-Lemli-Opitz syndrome.
- 7 dehydro cholesterol reductase
- Describe 4 regulatory mechanisms of cholesterol synthesis.
-
1. Excess cholesterol leads to (-) feedback via blocking to the the binding protein that stops the sterol regulatory elements from inhibiting transcription and translation
2. local control: AMP stimulates the protien kinase that phosphorylates HMG Co A reductase, rendering it inactive.
3. In glucagon world enzymes are phosphorylated rendering them inactive (See above)
4. Pharmicalogic –The statin drugs mimic HMG CoA. - Describe the structure of the cholesterol storage molecule.
- For cholesterol to be a storage molecule we simply need to esterify it with a FA
- Recognize the mechanism of Vitamin D activation.
-
7-DHC is converted by UV LIGHT in the SKIN to
VITAMEN D3 (CHOLECALCIFEROL) where it is converted by 25-HYDROXYLASE in the LIVER to become
25-HCC where it is converted by 1-ALPHA HYDROXYLASE in the KIDNEY to become
1,25 DHCC where it goes to the INTESTINES and helps to increase Ca++ - Describe the structure and function of bile acids.
- Bile acid has hydrophilic and hydrophobic side this enables formation of mycell which are water soluble yet can corral hydrophobic FA in center for break them down
- Identify the mechanism of bile acid sequestrants.
- Bile acids are made in liver & stored in gall bladder-. BA get sent to Intestine & form mycells to capture the fat acids. Some FA are exreted into the feces. Bile acid sequestering drugs aid in the excretion of bile acids into feces
- Describe the structure and function of lipoproteins.
-
Sx: lipid covering & cargo with protein stuch on outside as license plate
Fx: carry dietary and endogenous sources of cholesterol in bloodstream - Recognize the presentation and the biochemical profile of a patient with Smith-Lemli-Opitz syndrome.
-
PE will show thick alveolar ridges of gums. No palate.
Simean crease on palms (lines meet)
Ambiguous genetals
4th & 3rd toe fused together
LAB TESTS:
Elevated 7DHC (substrate)
Decreased 7DHCR -
Identify a patient with Vitamin D deficiency and evaluate a specific patient for treatment types.
3 organ problems and what type of suppliment can be given – 3 scenarios & 3 tx types. - --
- Identify the dietary and endogenous sources of cholesterol.
-
Dietary: organ meats, the yolk of eggs
Endogenous: Liver, intestine, adrenal cortex, reproductive tissues - Identify the enzyme deficiency in Smith-Lemli-Opitz syndrome
- 7 dehydrocholesterol 7 reductase (7-DHCR)