Exam 2: Pancreas Flashcards
5 hormones pancreas secretes
Insulin Glucagon Somatostatin Pancreatic polypeptide Ghrelin
Endocrine cells of pancreas arranges in clusters called
Islets of Langerhans
Islets of Langerhans make up ____% of pancreas
1-2%
4 cell types in Islets
Alpha
Beta
Gamma
PP
Alpha cells make up ___% and secrete ___
20% (outer rim)
Glucagon
Beta cells make up ___% and secrete ____
65% (central core)
Insulin
Gamma cells make up ___% and secrete ____
10% (interspersed)
Somatostatin
PP cells make up __% and secrete ___
5%
Pancreatic polypeptide
SNS innervation of islet cells is
Adrenergic
Peptidergic
Para innervation of islet cells is
Cholinergic
Peptidergic
Pre para fibers from _____ synapse with post cholinergic and peptidergic neurons in ____
Dorsal motor nucleus of vagus
Pancreatic ganglia
Vagal stim via _____ stimulates release of ___
ACh and VIP
Insulin
Pre sym cell bodies originate in ____ and synapse w/ post fibers in ____
Intermediolateral horn cells of cord
Paravertebral and celiac ganglia
Sym nerve fibers cause stim of ___ and inhibition of ____ in pancreas
Glucagon
Insulin
Insulin is synthesized and secreted by
B cells
Preproinsulin
Signal peptide
A chain
B chain
C peptide
Proinsulin
A chain
B chain
C peptide
Proinsulin is shuttled to ER where
Disulfide bridges form
In the golgi, proinsulin where
C peptide is removed
Secreted in granules
Insulin is stored in
Secretory granules complexed with zinc
Levels of C peptide accurately reflect ___ function
Beta cell
Used for type I diabetes patients
Group of GI tract hormones that inc insulin release after eating
Incretins
2 major incretins
GIP
GLP
Incretins slow rate of intestinal absorption by
Slowing rate of emptying of stomach
May dec food intake
Incretins inactivated by
Dipeptidyl peptidase 4 (DPP-4)
DPP-4 inhibitors
Dec blood glucose by preventing breakdown of GIP and GLP
FA and AA ____ insulin secretion
Stimulate
Insulin receptor
Tetramer
Insulin binds to alpha subunits
Insulin-receptor complex becomes internalized by
Endocytosis
Once inside cell, insulin is either ___, ____, or ____
Degraded; stored; recycled
Insulin can down regulate its own receptor by
Dec rate of synthesis
Inc rate of degradation
Insulin ensures that excess nutrients are stored:
Glycogen — liver
Fat — adipose
Proteins — muscle
Insulin decreases ____ blood concentrations
Glucose
FA and ketoacid
AA
Insulin promotes __ uptake into cells
K+ and glucose
Insulin also has a direct effect on ____ by stimulating ____
Hypothalamic satiety center
Ventromedial nucleus
Insulin directs the insertion of ___ into cell membranes
GLUT4
Insulin promotes formation of ____ in liver and muscle
Glycogen
Insulin inhibits ____
Glycogenolysis and GNG
Insulin in adipose
Stims fat deposition
Inhibits lipolysis
Insulin in liver
Dec FA degradation — dec acetyl CoA
How insulin dec blood AA
Inc AA and protein uptake
Inc protein synthesis and dec degradation
Tissues that don’t need insulin for uptake
Brain RBCs Intestine Cornea Kidney Liver Exercising muscle
GLUT2 is insulin ____
Independent
Glucose transport into pancreatic beta cells is via
GLUT2
Type 1 Diabetes
Insulin dependent
Destruction of B cells (autoimmune)
Type 1 Diabetes effect on concentrations in blood
Inc blood glucose, FA, ketoacid, AA
Lose lean body mass and adipose
Inc ketoacid in type 1 diabetes leads to
Metabolic acidosis (diabetic ketoacidosis)
Other effects of Type 1 diabetes
Glucosuria
Hyperkalemia
Hyperkalemia can lead to
Muscle flaccidity and weakness
Type 2 diabetes
Non-insulin dependent
Insulin resistance
Type 2 diabetes often occurs w/
Inflammation associated w/ obesity
Inflammation causes adipocytes to secrete
Inflammatory mediators: IL-6 and TNF
IL-6 and TNF induce signaling cascades that
Inhibit insulin receptors to function
Type 2 diabetes causes by
Down regulation of insulin receptors
Insulin resistance
Normal individuals concentration of glucose between meals
90 mg/dL
A1C test reflects average blood glucose level for past
2-3 months
A1C test measures
Percentage of Hemoglobin that is glycated
Normal A1C levels
4-5.6 mg/dL
Pre diabetic A1C level
5.7-6.4 mg/dL
Diabetic A1C level
> 6.5 mg/dL
Glucagon is synthesized and secreted by
Islet alpha cells
Glucagon promotes mobilization and utilization of
CHO
Fats
AA
Glucagon is synthesized as
Preproglucagon
Glucagon is stored in
Dense granules
Stim factors of glucagon
Fasting Dec glucose and AA CCK Epi/NE Ach GIP
Inhibitory factors of glucagon
Glucose Insulin Somatostatin Inc FA and ketoacid GLP-1
Main site of action of glucagon
Liver
Glucagon maintains _____ in fasting state
Blood glucose
Glucagon stims liver to produce/secrete
Glucose and ketone bodies
Glucagon effect on metabolism
Inc glycogenolysis
Inc GNG
Lipolysis
Glucagon inc GNG by
Dec F26BP which dec PFK activity
AA and lipolysis shunts substrates toward
GNG
Glucagon inhibits formation of ____ from glucose
Glycogen
Most important determinant of glucagon secretion
Concentration of glucose
Plasma glucose >200 mg/dL, secretion of glucagon is
Maximally inhibited
Dec blood glucose leads to ____ glucagon secretion
Stimulation
Insulin ____ glucagon secretion
Inhibits
Glucagon ____ insulin secretion
Stimulates
FFA ____ glucagon secretion
Inhibit
Glucagon secretion _____ by protein rich meal
Stimulated
Digestion of protein rich foods stims release of CCK/GIP which
Stims pancreatic islet cells
both insulin and glucagon release
Inc secretion of glucagon after protein meal serves to:
Prepare liver to dispose of AA by GNG
Signals liver to release glucose
Somatostatin secretion stim by
Ingestion of all nutrients
Glucagon
B-adrenergic agonists
Somatostatin secretion inhibited by
Insulin
Somatostatin inhibits secretion of
Insulin and glucagon
Somatostatin functions to
Modulate/limit responses of insulin and glucagon
Function of pancreatic polypeptide
Self-regulate pancreas secretory activities
Effect hepatic glycogen levels and GI secretions
Secretion of PP increased after
Protein meal
Fasting
Exercisa
Acute hypoglycemia
Secretion of PP decreased by
Somatostatin
IV glucose
Ghrelin secreted mainly by
Stomach mucosa between eating
Ghrelin can be produced by other tissues:
Pancreas
Brain
Ovary
Adrenal cortex
Ghrelin is released into blood and can cross ____ which affects ____
BBB
Hypothalamus
Ghrelin ____ feelings of hunger
Inc
Stims hypothalamic neurons in appetite control centers
Ghrelin effect on GI tract
Inc gastric acid secretion
Inc gastric motility
Inc gastric emptying
Stim of ghrelin receptors on afferent neurons initiates
Vago-vagal reflexes and local enteric reflexes
Only GI tract hormones that promotes food intake
Ghrelin