Test 3: lecture 9 Flashcards
endocrine function of pancrease
by the islets of langerhans
beta cells produce- insulin and amylin
aplha cells produce glucagon
delta cells produce somatostain
beta cells produce-___
alpha cells produce ___
delta cells produce ___
insulin and amylin
glucagon
somatostain
delta cells produce ___ which ___
somatostatin
inhibit alpha and beta cells- inhibits insulin and glucagon
insulin is made of ___
small peptide hormone
two chains connected by disulfide bond
made by beta cells in the islet of langerhans in the pancreas
made as precursor preproinsulin
what is the precursor of insulin
preproinsulin
how does preproinsulin become insulin
signal peptide cleaved to form proinsulin
GH → IGF-1 (somatomedin C)
c- protein degradation by insulinase in the liver → insulin
C protein of proinsulin is similar to
GH → IGF-1 (somatomedin C)
formation of insulin receptor
2 alpha 2 beta subunits
binding of insulin causes Beta subunit to be phosphorylated and becomes a kinase that will phosphorylate other enzymes
binding of insulin to insulin receptor causes
glucose transport, protein synthesis, fat synthesis, glucose synthesis, growth and gene expression
where are GLUT4
insulin-dependent tissues (muscle and adipose tissues).
where kind of GLUT are in insulin independent tissues
GLUT 1,2,3,5
what kind of GLUT are Beta cell glucose sensor
GLUT2
when insulin bind to the receptor it causes GLUT4
to move from golgi to the plasma membrane
stimulates glucose uptake
uptake of monosaccharides
insulin independent
metabolic effects of insulin
Profound effects on metabolism of carbohydrate, fat and protein.
Promote storage of glucose as glycogen
Promote protein synthesis and storage
Promote fat synthesis and storage
Insulin is associated with “energy abundance”.
___ increases protein and fat synthesis and storage
insulin
insulin promotes storage of ___ as ____
glucose
glycogen
insulin causes the increased uptake, storage and use of glucose by most tissues:
liver, muscle and adipose tissue
Lack of insulin causes ___
hyperglycemia (high blood sugar)
what enzymes are stimulated by insulin
glucokinase
glycogen synthase
glycogenesis → formation of glycogen from glucose
why cant glucose be stored in the liver
too much osmotic pressure
needs to be stored as glycogen
if there is excess glucose where is it stored
first in the liver as glycogen
then in the muscles as glycogen
then converted into fatty acids (triglyceral) and stored in the liver
effect of insulin on fat metabolism
promotes fat synthesis and storage
Insulin increases utilization of glucose by most tissues - fat sparer.
Insulin promotes fat synthesis in the liver.
Insulin promotes fat storage in the adipose cells.
how to form fat synthesis in the liver
glucose → triglyceride in liver then lipoprotein lipase → fatty acids which can be taken into cells and converted back into triglycerides for storage
