biochem Flashcards
what does anorexigenic mean?
makes you want to eat less and be more active
what does orexigenic mean/
makes you want to eat more and be less active
what nucleus contains the anorexigenic and orexigenic neurons
arcuate nucleus
how does leptin regulate storage of fat?
released with excess adipose to signal to decrease wt
it is an adipokine
what pathway does leptin work through?
non-receptor tyrosine kinase (JAK/STAT)
what does adiponectin do?
downregulates inflammatory response
works opposite leptin
how does increased fat lead to inflammation
inc fat -> inc leptin
this leads to dec adiponectin and so less antiinflammatory protection
What are the characteristics of homozygote leptin deficiency?
normal birthwt, but obese in childhood
severe hunger w/ being aggressive
tx with recombinant leptin therapy
which hormones are anorexigenic?
leptin, insulin, amylin, PYY, CCK
what hormones are orexigenic?
ghrelin
what hormone does the pancreas release?
insulin
amylin
what hormone does adipose release?
leptin
what hormone does the ileum release?
PYY (down regulates ghrelin)
what hormone does the stomach release?
ghrelin
what hormone does the duodenum release?
CCK
what are the actions of ghrelin?
released when baroreceptors sense the stomach is relaxing
stim. orexigenic neurons to release GH
When is CCK released?
when AA or FA enter the duodenum thereby signaling the release of bile by the gall bladder, amylase by the pancreas and signals satiety
what anorexigenic and orexigenic hormones are released from the hypothalamus?
anorexigenic: CART, alpha-MSH
orexigenic: NPY, AgRP
What hormones work on NPY hormone?
ghrelin stim
PYY inhib
LEptin and insulin inhib
what hormones work on alpha MSH hormone/
insulin and leptin stim
what receptors do alpha MSH bind?
MCR3 and 4
what receptors do AgRP bind?
MCR4 (antagonizes) and Y1R
what is the strongest activator of glycolysis
F2,6BP
what is the regulatory step of glycolysis
fructose 6-p to fructose 1,6 bp
regulated by phosphofructokinase-1
what does phosphokinase-2 do?
convert F6p to F2,6BP
what does fructose 2,6 bisphosphatase do
removes p from F2,6BP leaving F6p (down regulates gluconeogenesis)
what signal lipoprotein lipase? what does it do?
insulni
it adds triacylglycerols to adipocytes for storage
what signals hormone sensitive lipase? what does it do?
glucagon
releases FA from adipocytes which then binds to albumin for transport to muscles
how does the FA get into the mitochondria? And what happens to it once it does
via acyl carnitine shuttle
once inside the FA is released to form acyl coa then goes to beta oxidation
will insulin upregulate or downregulate HMG coa reductase to make cholesterol?
upregulate
what is the rate limiting step for FA biosynthesis?
acetyl coa conversion to malonyl coa
via acetyl coa carboxylase
does citrate signal high or low energy?
high energy
does acetyl coa signal high or low energy
high energy
how does the body get acetyl coa from mito to cytosol for FA biosynthesis?
using citrate shuttle
what is the rate limiting step of beta oxidation?
when FA shuttled by carnitine acyl transferases
What enzyme is used to form ketone bodies from hmg coa
hmg coa lyase
what enzyme is used to form cholesterol from hmg coa
hmg coa reductase
turns it to mevalonate which is need to build cholesterol
What is von gierke disease? what tissue is most affected
aka glycogen storage dz type 1
glucose 6 phosphatase deficiency
onset in childhood
liver is most affected
what are the genetics of von gierke?
AR
what are the symptoms of von gierke/
fast induced hypoglycemia seizures failure to grow hyperlipidemia hyperuricemia
what is the effect of ribose 5p build up associated with von gierke
will drive production of purines leading to gout
how does von gierke fasting glucose compare to normal?
peaks at meals like normal but plummets in between as they are unable to perform gluconeogenesis or glycogenolysis
what is the dietary treatment for von gierke?
uncooked corn starch every 1-3 hrs
why do von gierke pts have hyperlipidemia?
mobilizes lipids to create energy source
what is the difference between von gierke type a and type b?
type a= inact of g6p
type b= inact of g6p transporter
what is pompe disease? genetics?
lysosomal acid alpha glycosidase def.
childhood onset
AR, all tissues
pathogenesis of pompe dz?
glycoen end up in lysosomes where acid alpha glycosidase breaks them down
with def, glycogen builds up in lysosome and is not released
what is cori dz? genetics?
amylo-1,6 glucosidase def
AR
effects liver heart and muscle
what is the pathogenesis of cori?
effects glycogen breakdown in cytosol
enzyme amylo-1,6 glucosidase debranches glycogen normally
with def, glycogen use is limited as only the outer portion is able to be broken down
what is McArdle? Genetics
myophosphorylase def
AR, muscle
childhood/adult onset
pathogenesis of McArdle?
unable to breakdown muscle glycogen
this leads to lack of muscle endurance
intense exercise can lead to rhabdomyolysis
