cholest Flashcards
strcuture of cholestrol
cyclic rings with a hydrophobic tail
The steroid ring structure is planar
function of cholestrol
is that it can increase and decrease membrane stiffness, depending on the temperature and the nature of the membrane
formation of c
liver through de novo synthesis of cholesterol from acetyl-CoA.
3 main steps Cholesterol Synthesis
1) Synthesis of isopentenyl pyrophosphate
2) Condensation of 6 moleclies of iso to form squalene
3) Cyclisation and demethylation to get cholestrol
how bile salts are formed
major breakdown products of cholesterol
what are the primary bile salt
glycocholate and also taurocholate.
what makes sterioids
…cholesterol…
what does chol generate using demolase
pregnenolone
what is pregnenolone
All five classes of steroid hormones come from pregnenolone: Progestagens, glucocorticoids, mineralocorticoids, androgens and oestrogens.
what is vitiman d
collective term for a group of steroids which are vital for the intestinal absorption of important ions needed for bone development
examples of vitimin d
calcium, phosphate and magnesium.
main source of vitimin d
our main source is from the activity of UV light upon 7-dehydrocholesterol in the epdermis of the skin.
what is `Calcitriol
most active vitamin D metabolite
function
plays a key role in calcium metabolism. It functions as a steroid hormone, binding to vitamin D response elements (VDREs) in the promoter of target genes and inducing key genes involved in bone metabolism
lack of calcitrol causes
in childhood leads to rickets
is Familial hypercholesterolaemia (FH) dominant
yes
what happens if a person is hetrozygotes
have cholesterol levels approximately 2-3 times higher than in normal people and are susceptible to atherosclerosis (hardening of the arteries) in middle age
and homozygotes
serum cholesterol levels are five times higher than in healthy individuals and severe atherosclerosis and coronary infarction may be observed in adolescence.
severe fh causes
lacked functional LDLRs LDL receptor (LDLR) Mutations in several domains of the LDL receptor lead to FH
what is hypercholesterolaemia
high cholesterol
how to control hypercholesterolaemia
Inhibition of de novo cholesterol synthesis by the liver, or the reduction of dietary cholesterol absorption by the intestines
resins method
These bind or sequester bile acid-cholesterol complexes preventing their reabsorption by the intestine
HMG-CoA-Reductase inhibitors/
statin
is that of a competitive inhibitor of HMG-CoA Reductase.
step 1
Formation of acetoactyl coA
2 acteyl coA to it
step 2 to HMG coA
acetoacetyl coa + acetyl coa
step 3 form melovonate
uses HMG coA reductase which can be controlled by negative feedback cholestrol bile salts and melavonate
