exam 2: insulin Flashcards
fendocrine pancreas. is 1%
islet of Langerhan cells:
A cells secrete=
B cells secrete=
D cells= (inhibitor)
F cells=
A cells secrete= glucagon
B cells secrete=insulin
D cells secrete= somatostatin (inhibits A and B cells)
majority of the islets of langerhan cells:
a and B cells
exocrine portion of pancreas is what releases _____ enzymes into the lumen of the small intestine
digestive
a and b cells go into_____ (why called endocrine)
into blood
majority of the pancreas is ____ cells that are moved into duadumen for digestion
acinar cells
insulin secretion is associated with
energy abundance
insulin is composed of two amino acid chains, connected by:
disulfide linkages
and a and b chains
when a and b chains are split in insulin, functional activity of insulin molecule is
lost
what have virtually no insulin activity
proinsulin and C peptide
formation of insulin occurs in ___ cells. it is first made as:
Beta cells
first made as proinsulin
in the golgi, proinsulin is cleaved to form
c peptide and insulin
insulin circulates entirely in
unbounded form
what is the key regulator of insulin secretion
glucose
when glucose levels ____, this stimulates insulin synthesis
increase (>3.9 mmol/L)
mechanism of insulin secretion.
- glucose enters cell _____ concentration gradient
- glucose is metabolized until it produces:
- when ATP ______, this _____ the SUR channel (sulfonylurea receptor channel)
- this causes depolarization of:
moving it: - causes Ca2+ channel to:
exocytosis - this kinda pushes the reaction onward and increases levels of cAMP
- exocytosis of
- down (high to low)
- ATP
- closes channels (it is a K+ gated channel gated by the presence of ATP) aka high atp=closed channel
- depolarization of K+ moving it away from its equlibrium
- Ca2+ channel opens (exocytosis)
- incretins
- exocytosis of insulin!
for treatment for _______, some medications close the SUR channel
type 2 diabetes mellitus
hormones produced by the digestive system that work to stimulate insulin secretion BEFORE plasma glucose is elevated.
GLP-1 and GIP
incretins
ozempic!!
normal fasting blood glucose is _______mg/100ml
80-90mg/100 ml
insulin secretion rises when blood glucose rises above
100 mg/100ml
peak insulin secretion occurs when blood glucose reaches
400-600 mg/100 ml
what is an antigonist of insulin
glucagon
glucagon levels decrease as ____ levels increase
insulin
as insulin secretion levels increase, glucose levels
until glucose levels get to
increase
get to 400-600
insulin is a ________ receptor
tyrosine kinase-linked receptor
the target cells responses:
______= increased glucose uptake especially by muscle cells and adipocytes due to translocation of vesicles containing GLUT-4 to the membrane
FAST in seconds.
glucose transport
the target cells responses:
the membrane becomes more permeable to many amino acids along with potassium and phosphate ions.
_______= change in enzyme activity leading to changes in metabolism
slower (10-15 minutes)
-fat synthesis
-protein synthesis
-glycogen synthesis
amino acids, ketones, various nutrients, gastrointestinal peptides (GLP-1), and neurotransmitters also influence ____ secretion
insulin
the target cells responses:
the membrane becomes more permeable to many amino acids along with potassium and phosphate ions.
____= changes in gene expression and growth
slowest
(hours to days)
insulin promotes muscle glucose uptake and metabolism-anabolic effect via
via GLUT-4:
(effects of insulin on muscle)
resting muscle membrane is
only slightly permeable to glucose
what stimulates increases of glucose transport and how?
insulin
via increase in GLUT-4 in the membrane
when the glucose comes in, there is going to be conversion of it into glycogen (anabolic effect) which increases:
increases glycogen storage in skeletal muscle
and
increases protein synthesis
and
inhibits protein degradation
(anabolic effects)
effect of insulin on protein metabolism and growth.
promotes ________ synthesis and ______. Inhibits:
-promotes protein synthesis and storage
-inhibits protein degradation
insulin and growth hormone interact SYNERGISTICALLY to promote
growth
lack of insulin causes:
1
2
protein depletion and increased plasma amino acids
effects of insulin on liver.insulin promotes the ____ and ___ of glucose as glycogen by the liver
insulin promotes the uptake and storage of glucose (as glycogen) by the liver
insulin promotes conversion of excess glucose into:
and inhibits:
fatty acids
inhibits production of new glucose aka gluconeogenesis
effect on insulin on fat metabolism. insulin promotes:
1
2
insulin promotes fat synthesis and storage
storage form of fatty acids are
triglycerides
increase glucose transport into adopocyte, increases number of TG-rich lipoproteins that enter the adipocyte (adipose tissues)
which activates _______ in the capillary walls of adipose tissues
leads to splitting ______ into fatty acids
and absorption into adipocytes
lipoprotein lipase LPL
splitting TG (triglycerides) into FA
how you break down triglycerides to put FA into blood:
we want to block this pathway because we need to store things
hormone-sensitive lipase
essential effects of insulin for fat storage in adipose tissue:
-inhibits action of HSL
-enhances glucose transport into adipocytes (to store)
(effects of insulin on Fat Metabolism)
lack of insulin causes _____ and release of _____ into the blood and increases plasma cholesterol and phosphlipids
lipolysis and release of FFA
net effects of plasma for major target tissues of insulin:
decrease in all
1. glucose
2. FFA
3. ketoacids
4. amino acids
increase insulin secretion when what 3 things are increased:
insulin will then let these go back down to normal levels
-blood glucose
-blood FFA
-blood amino acids
what happens for insulin secretion to be decreased
-decreased blood glucose
-fasting
somatostatin (inhibits insulin and glucagon)
other things that increase insulin secretion:
-SUR drugs (close K channel and cause depolarization
-GLP-1
-GIP
-PNS
-insulin resistant; obesity
these increase blood glucose and eventually cause insulin to decrease blood glucose levels to keep in window:
-glucagon
-GH
-cortisol
