Exam 2: Pancreas Flashcards by Sarah Kucza

5 hormones pancreas secretes

Insulin
Glucagon
Somatostatin
Pancreatic polypeptide
Ghrelin

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Endocrine cells of pancreas arranges in clusters called

Islets of Langerhans

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Islets of Langerhans make up ____% of pancreas

1-2%

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4 cell types in Islets

Alpha
Beta
Gamma
PP

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Alpha cells make up ___% and secrete ___

20% (outer rim)

Glucagon

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Beta cells make up ___% and secrete ____

65% (central core)

Insulin

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Gamma cells make up ___% and secrete ____

10% (interspersed)

Somatostatin

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PP cells make up __% and secrete ___

Pancreatic polypeptide

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SNS innervation of islet cells is

Adrenergic

Peptidergic

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Para innervation of islet cells is

Cholinergic

Peptidergic

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Pre para fibers from _____ synapse with post cholinergic and peptidergic neurons in ____

Dorsal motor nucleus of vagus

Pancreatic ganglia

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Vagal stim via _____ stimulates release of ___

ACh and VIP

Insulin

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Pre sym cell bodies originate in ____ and synapse w/ post fibers in ____

Intermediolateral horn cells of cord

Paravertebral and celiac ganglia

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Sym nerve fibers cause stim of ___ and inhibition of ____ in pancreas

Glucagon

Insulin

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Insulin is synthesized and secreted by

B cells

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Preproinsulin

Signal peptide
A chain
B chain
C peptide

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Proinsulin

A chain
B chain
C peptide

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Proinsulin is shuttled to ER where

Disulfide bridges form

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In the golgi, proinsulin where

C peptide is removed

Secreted in granules

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Insulin is stored in

Secretory granules complexed with zinc

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Levels of C peptide accurately reflect ___ function

Beta cell

Used for type I diabetes patients

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Group of GI tract hormones that inc insulin release after eating

Incretins

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2 major incretins

GIP

GLP

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Incretins slow rate of intestinal absorption by

Slowing rate of emptying of stomach

May dec food intake

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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