13.9 steroids kyleigh moyer taylor raker. what are steroids? a compound containing this ring...
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13.9Steroids
Kyleigh MoyerTaylor Raker
What are Steroids?
A compound containing this ring formation
Three cyclohexane rings
Another cyclohexane ring is fused
Not necessarily esters but some are
CholesterolMost abundant and most important steroid in the human body
Plasma membrane in all animal cells
Second important function – synthesis of steroidsEx. Sex Hormones, adrenocorticoid
hormones
Cholesterol
Free form and esterified Gallstones – free cholesterol
High Serum Cholesterol and diseasesFear of Cholesterol
Necessary for human lifeProduced by liver and body doesn’t need to take in by diet
When it reaches 150 mg/100 mL the liver reduces production by half
Cholesterol
In the body it's a dynamic stateConstantly circulated in bloodHydrophobicCholesterol
Cholesterol esters
Need water-soluble carrier to circulate in blood
Lipoproteins: Carriers of Cholesterol
Contain core hydrophobic lipidShell of hydrophilic molecules
•High-density lipoprotein (HDL)
Good Cholesterol
33% Protein
30% Cholesterol
ChylomicronsCarry Dietary Lipids
Synthesized in intestines
LipoproteinsLow-density lipoprotein (LDL)Bad Cholesterol
25% Protein
50% Cholesterol
Very-low-density lipoprotein (VLDL)Carries triglycerides (fats)
Synthesized by Liver
Transportation in LDLStarts out as large VLDL particlesCore contains triglycerides and cholesteryl estersSurrounded by polar coatWhen they reach muscles or fat tissuesTriglycerides and proteins are removed
Core shrinks and it become more dense LDL
Transportation in LDLCarried Cholesterol specific LDL-receptorsConcentrated areas called coated pitsAfter bindingLDL is taken inside
Liberates cholesterol from cholesteryl estersIn receptors are low then cholesterol builds up in blood
Transportation in HDLPeripheral tissues to liver Transfers to LDL
In serum converted to cholesteryl estersDelivered to liver for synthesis of bile acids and steroid hormonesBinds to liver cell surfaceTransfers cholesteryl esters to cell
Reenters circulationWant high levels – gets rid of cholesterol
Insoluble in water Higher levels
Plaque build up Atherosclerosis
High BP Heart attack Stroke
Smaller diameter blood vessels Deprive cells of oxygen
Most cholesterol transported by LDL If there's enough LDL-receptors levels drop When levels are high
Less receptors Low levels
A lot of receptors Not enough
Familial hypercholesterolemia
High plasma cholesterol levels Lacks LDL-receptors Or not concentrated on coated pits
High LDL means his cholesterol Serum cholesterol levels control
Synthesis by liver High levels – low synthesis
Reduce serum cholesterol Number of drugs
Inhibit liver synthesis Inhibits an essential enzyme More LDL enters cells Premenopausal women have more HDL
1. What’s the common structure of a steroid?
2. What’s the second most important function of steroids?
3. What’s the most abundant steroid?
4. What is the core of a lipoprotein?
4/21/12