Endocrine Pancreas Flashcards Preview

E: Regulatory Physiology & Pharmacology > Endocrine Pancreas > Flashcards

Flashcards in Endocrine Pancreas Deck (29):
1

Define the pancreas?

Triangular gland

Which has both exocrine and endocrine cells

Located behind the stomach.

 

2

Exocrine?

Secretes into a duct

3

Endocrine?

Secretes directly into the blood stream

4

What are the cells in the pancrease that produce exocrine product?

Acinar cells.

Produce an enzyme-rich juice used for digestion

5

What is the name for the cells that produce endocrine products?

Pancreatic islets.

Islets of langerhans.

Produce hormones involved in regulating fuel storage and use.

6

What are the key parts of the pancreas?

Pancreatic duct (goes into the lumen of the gut)

Islets

Pancreatic acinar cells

A image thumb
7

the different cells in the Islets of Langerhans?

Beta cells: produce insulin 

alpha cells: produce glucagon

Delta cells: produce somatostatin.

F cells: produce pancreatic polypeptide. 

8

The location in the pancreas of the cell types?

A image thumb
9

Insulin?

Protein hormone

Consisting of two amino acid changes linked by disulfide bonds.

Produced as pro-hormones first until they reach the site of action.

A image thumb
10

Why are enzymes synthesised as pro-enzyme instead of active enzyme?

So the do not digest the cells they are manufactored in.

eg. if insulin were to be active it would digest the pancreatic cells.

11

Insulin synthesis?

DNA (in beta cells)   ->

mRNA    ->

Preproinsulin (contains an addition polypeptide sequence at the N-terminal)   --->

Proinsulin --->

Insulin

12

Insulin synthesis and release?

mRNA binds to preprohormone. 

Enzymes in the ER remove the signal sequence producing prohormone.

Prohormone passes from ER to Golgi apparatus.

Secretory vesicles contain enzymes and prohormones making hormone.

Hormone is released into the extracellular space

13

What effects the synthesis of insulin?

Glucose or feeding

Decreased by fasting

14

What is the threshold of glucose-stimulated insulin secretion?

100mg/dl

15

How does glucose stimulate insulin secretion?

GLUT2 uptakes glucose into the beta cells. 

Glycolysis- increase in ATP.

ATP-sensitive potassium channel- inward movement of potassium.

Depolarisation of the cell.

Inward calcium movement: by voltage-gated calcium channel.

This calcium stimulates the release of the insulin vesicles.

16

Regulators of insulin secretion?

Stimulators:

Increase in serum glucose.

Hormones.

 

Inhibitors:

Decrease glucose

Hormone: SS.

 

17

What level of plasma glucose when no insulin is produced?

below 50mg/dl

18

What level of plasma glucose when half-maximal insulin response occurs?

At 150mg/dl

19

What level of plasma glucose conc when a maximum insulin response occurs?

At 300mg/dl

20

Insulin is biphasic?

Meaning

It has two phrases of production

upon glucose stimultion: initial burst.

second phase: gradual increment. Lasts as long as blood glucose levels are high

21

Graph representing the insulin secretion?

Peak straight after increase in glucose levels.

 

A image thumb
22

Glucagon?

Polypeptide hormone

Potent hyperglycemic agent.

Produced by alpha cells in the pancreas

23

What does glycagon target and what does it promote?

Major target is the liver.

Promotes glycogenolysis: breakdown of glycogen to glucose.

Gluconeogenesis: synthesis of glucose from lactic acid.

Release of glucose to the blood from liver cells.

24

Glucagon synthesis?

DNA in alpha cells

mRNA

Preproglycagon

Proglycagon

Glycagon

25

Factors affecting glucagon secretion?

Stimulation:

decrease in blood glucose, Increase in serum amino acid, stress and exercise.

 

Inhibitiors:

SS, Insulin, increase in blood glucose

26

What kind of feedback happens on glucagon when the plasma glucose increase?

Negative feedback onto the alpha cells

Decreases the glycagon levels

27

Insulin and Glucagon together?

Regulate metabolism

A balancing act. 

Levels of glucose in blood low: glucagon needed.

Level of glucose are high: insulin needed.

28

Somatostatin?

Secreted by delta cells.

Inhibitory effects.

Released to same stimuli as insulin.

 

29

Pancreatic polypeptide hormone?

Secreted by the F cells

Release in response to the high protein meal, low blood sugar and stenous exercise.

Inhibits gall bladder and pancreatic exocrine secretion.