endocrine pancreas and glucose regulation Flashcards
functional anatomy of the pancreas
98% exocrine
-digestive enzymes and bicarbonate
-secreted thru pancreating duct
2% endocrine
-peptide hormones regulating glucose and other intermediary metabolism
-secreted by exocytosis- drains into hepatic portal vein
what are the exocrine cells of the pancreas
duct and acinar cells
-NaHCO3 and digestive enzymes
what cells are the endocrine portion of the pancreas
islets of langerham
hormones secreted by islet cells
B/ beta cells secrete insulin and amylin
A/ alpha cells secrete glucagon
D cells secrete somatostatin GHIH
PP cells secrete pancreatic polypeptide
role of insulin
stimulate uptake and storage of energy substrates
role of glucagon
stimulates production of glucose by liver- gluconeogenesis
somatostatin role
general inhibition of exocrine and endocrine pancreatic secretion/ acts in paracrine fashion
panceatic polypeptide role
inhibition of exocrine pancreatic secretion
what is the role of pancreatic hormones
what is the role of pancreatic hormones
provide constant supply of glucose to CNS
what do pancreatic hormones respond to
feasting and fasting
when does the absorptive or fed state occur
first hours after eating
when does the postabsorptive or fasted state occur
between meals
what is the most significant regulated variablee
blood glucose concentration
what does excessive glucose in the brain do
has detrimental effects long term due to inapproperiate glycosylation reactions
what controls insulin and glucagon secretion
blood glucose concentration
what hormone is dominant in the fed state
insulin
what does insulin do
cellular uptake of nutrients
carb and fat storage
protein anabolism
what does glucagon do
catabolism
breakdown of fat, car, and protein
when is glucagon dominant
in the fasted state
what are some factors that affect insulin secretion
high aa level
glucose entry in small intestine stimulating
-GIP- gastric inhibitory peptide/ glucose dependent insulinotropic peptide
-GLP1- glucagon like peptide 1
higher parasympathetic activity- innervation of beta cells
what accomplishes passive facilitated diffusion of glucose across cellular membranes
GLUTs 1-6
what GLUTs are alwyas present in their respective cell membranes and what is this called
all but 4
limited tissue distribution
where does glut 1 transport glucose
across BBB
GLUT 4
insulin depepndent transporter that is recruited to membrane upon insulin binding to its receptor— reversible process
where does GLUT4 transport glucsoe
skeletal muscle and adipose
is insulin needed for glucose uptake in exercising muscle
no
muscle contraction caues insertion of GLUT 4 into cell membranes
what does the brain and liver not need for glucose uptake
insulin
what does chronically high insulin level lead to
down regulated receptors
what decreases affinity of receptors
excess glucocorticoids- stress response
what upregulates insulin receptors
starvation
what increases affinity of insulin receptors
chronically low insulin levels or adrenal gland insufficiency
major effects of insulin on carbohydrate metabolism
decreases blood glucose and increases carb storage
major effects of insulin on carbohydrate metabolism detail
inc glycogenesis in skeletal muscle and liver
dec in hepatic glucogoneogenesis
inc in glucose uptake by fat cells and resting skeletal muscle
how do atheletes abuse insulin
inject insulin and then eat high sugar good attemtping to increase glycogen storage in skeletal muscle
what is the risk of injecting insulin
hypoglycemia and coma bc they get the fast acting insulin
synthetic insulin allowance
it is banned for atheletes and is sensed by sensitive assays
insulin effect on fat metabolism
decreaes bloody fatty acids and inc triglyceride storage
inc transport of fa into fat cells
inc triglyceride synth by increasing glycose transport into gat cells
activates enzymes that catalyze synth of fa from glucose
inhibits lipolysis
insulin effect on protein metabolism
dec blood AA and inc protein synthesis
inc transport of blood AA into muscle and other cells
inc protein synth
inhibits protein degradation
what are some other factors influencing insulin secretion
inhibition of insulin by somatostatin- paracrine from D cells
-inc sympathetic activity
-during exercise or acute stress
-ensures glucose supply to brain and active muscle
primary control of glucagon secretion
negative feedback bw alpha cells and blood glucose concentratino
-dec in blood glucose inc glucagon secretion
what are some factors that increase secretion of glucagon
sympathetic activity
inc in AA counteracts insulin effect and prevents hypoglycemia after high protein low carb meal
effect of glucagon on fat and carb metabolism
opposite of insulin
inc blood glucose by inc liver gluconeogenesis and glycogenolysis
inc blood FA and ketone bodies by increasing production in liver and fat
-inc lipolysis and metabolism of FA to ketone bodies
-dec triglyceride synthesis
glucagon relatino to hypo and hypersecretion of pancreatic hormones
no known assocaited with glucagon
hypersecretion of insulin- hypoglycemia
hypoglycemia
beta cell tumor
overdose of insulin in diabetics
CNS effects- sweating, palor, inc heart rate, anxiety, confusion, convulsions, coma
diabetes mellitus
undesecretion or resistance of insulin- HYPERGLYCEMIA
what does high glucose do to blood vessels
damages them by glycosylation reactions
neuropathy, nephropathy, cardiovascular disease
how many diabetics are type 1
10%- IDDM
how many diabetics are type 2
90% NIDDM- non insuolin dependant
how is diabetes mellitus diagnosed
glucose tolerance test
type 1 diabetes
autoimmune destruction of beta cells
insulin dependant
daily insulin injections
