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
Insulin activates ___ in the capillary walls of adipose tissue to release fatty acids.
lipoprotein lipase
Insulin promotes glucose transport into fat cells –> a-glycerophosphate –> ___ portion of fats.
glycerol
insulin ___hormone-sensitive triglyceride lipase in adipose cells.
inhibits
insulin deficiency causes
increase hormone-sensitive lipase –> lipolysis of triglycerides and release of free fatty acids.
increase conversion of fatty acids into cholesterol and phospholipids in the liver.
Excessive usage of fat causes ketosis and acidosis. Fatty acids –> acetyl Co-A –> acetoacetic acid –> acetone and b-hydroxybutyric acid.
insulin deficiency causes ___ hormone-sensitive lipase –> lipolysis of triglycerides and release of free ___
increase
fatty acids.
insulin deficiency causes ___ conversion of fatty acids into cholesterol and phospholipids in the ___.
increased
liver
insulin deficiency causes excessive usage of fat causes ___
ketosis and acidosis.
glucose can’t be used so body uses fat for energy
insulin deficiency increases the metabolic use of ___
fats
use fats instead of glucose for energy
what happens if you remove pancreas
profound effect on fatty acid metabolism
how does insulin effect protein metabolism
Insulin promotes protein synthesis and storage
increases transport of amino acids into the cells.
increases transcription and translation.
decreases protein catabolism.
decreases gluconeogenesis in the liver.
Insulin deficiency causes protein depletion and increased plasma amino acids.
Insulin and growth hormone function synergistically to promote growth.
insulin will cause the ___ of protein catabolism and gluconeogenesis in the liver.
decrease
insulin will cause the ___ transport of amino acids into the cells and the ___ transcription and translation.
increased
increased
Insulin ___causes protein depletion and increased plasma amino acids.
deficiency
causes weight loss
both ___ and ___ are required for growth
GH and insulin
to allow uptake of all 20 amino acids into the cells
what are some stimulators of insulin secretion
Increased blood glucose
Increased blood free fatty acids
Increased blood amino acids
Insulin resistance; obesity
Cortisol
Growth hormone
what are some inhibitors of insulin secretion
Decreased blood glucose
Fasting
Somatostatin
Catecholamines
catecholamines and somatostatin will cause ___
inhibit of insulin secretion
somatostatin (IGF-1)
___ is secreted by alpha cells in the islets of langerhan and stimulate ___ and ___
glucagon
increase breakdown of glycogen in the liver (glycogenolysis)
increase gluconeogenesis in the liver. (making glucose)
precursor for glucagon can also turn into ___
preproglucagon
other peptides in the GI
stimulators of glucagon secretion
Decreased blood glucose
Increased blood amino acid
Exercise
inhibition of glucagon secretion
Increased blood glucose
Somatostatin (Islet delta cells)
how is blood glucose regulated
insulin tries to lower BG
glucagon tries to increase BG
Severe ___ stimulates sympathetic system to release ___ which causes ___
hypoglycemia
Epinephrine –> release of glucose from the liver
Prolonged hypoglycemia leads to release of ___ and cortisol.
GH
severe hypoglycemia decrease the rate of glucose utilization by most cells (___ resistance) and cause ___
severe hypo → causes release of GH and cortisol
insulin
stimulate gluconeogenesis by the liver (make glucose in the liver)
what three tissues use only glucose for energy
brain
retina
gonads
(insulin has no effect on these tissues)
what tissues have no effect by insulin
brain
retina
gonads
type 1 DM
insulin-dependent diabetes (IDDM)
not enough insulin made
occurs randomly 10%, usually in younger people
plasma glucose is increased and plasma insulin is low or absent
treatment: give insulin
Type II DM
non-insulin-dependent diabetes (NIDDM), insulin resistance.
happens in older obese people (80-90%)
increased plasma glucose and insulin
insulin can’t get into cells= decreased insulin sensitivity
treatment: diet and weight loss and insulin and other drugs
what can cause DM
Genetic predisposition
Pancreatic injury: trauma, neoplasia, infection, autoantibodies, inflammation, drugs (Type I)
Hormone-induced b-cell exhaustion: growth hormone (too much GH in gigantism), cortisol (too much cortisol).
Target tissue insensitivity (Type II)
Decreased number of insulin receptors
Defective insulin receptors
Defect in post-receptor signaling
