The Endocrine Pancreas

Question 1

What fuses to form pancreas

Answer 1

2 pancreatic buds at junction of foregut and midgut

Question 2

The pancreas is posterior to ____ curvature of stomach

Answer 2

greater

Question 3

How long is the pancreas

Answer 3

12-15cm

Question 4

Where do the larger ducts travel?

Answer 4

Connect to common bile duct form liver and gallbladder, then enter duodenum as a common duct through the the hepatopancreatic ampulla

Question 5

Pancreas is formed of small clusters of ___ epithelial cells

Answer 5

glandular

Question 6

the clusters of cells in the pancreas are called

Answer 6

acini

Question 7

Exocrine activity of pancreas is performed by

Answer 7

acinar cells (make and secrete fluid and digestive enzymes = pancreatic juice)

Question 8

Endocrine activity of pancreas is performed by

Answer 8

Islet cells (make release several peptide hormones into portal vein)

Question 9

What digestive enzymes does the pancreas release?

Answer 9

Amylase - carb
Trypsin, chymotrypsin, elastase - protein
Lipase - triglycerides

Question 10

What is the site of insulin and glucagon secretion in the endocrine pancreas?

Answer 10

Islet of Langerhans

Question 11

What cells secret glucagon?

Answer 11

alpha cells

Question 12

What cells secrete insulin

Answer 12

Beta cells

Question 13

What cells secrete somatostatin (SST)

Answer 13

Detta cell

Question 14

What is paracrine “crosstalk” in pancreas?

Answer 14

Communication between alpha and beta cells (local insulin release inhibits glucagon)

Question 15

Role of insulin

Answer 15

Stimulates glucose uptake in to cells and carb catabolism.
Stimulates lipid synthesis by adipose tissue and stimulates protein synthesis

Question 16

Role of glucagon

Answer 16

Glycogenolysis in liver

Lipid hydrolysis in adipose tissue which leads to increase ketogenesis

Increase gluconeogenesis from available amino acids

Question 17

What does insulin suppress?

Answer 17

Lipolysis
Breakdown of muscle (decreased ketogenesis)
Glycogenolysis
Gluconeogenesis

Question 18

Glucagon inrcreases

Answer 18

hepatic glucose output (increased glycogenolysis, increased gluconeogenesis)

Peripheral release of gluconeogenic precursors (lipolysis, muscle glycogenolysis and breakdown)

Question 19

Pathway of insulin secretion in beta cell

Answer 19

Glucose enters cell via GLUT2 glucose transporter (amount depends on conc. of glucose)

Glucokinase activated

The glucose is phosphorylated to glucose 6-phosphate

Rate of glycolysis is increased

ATP generated, closes KATP channel, stopping efflux of K+.
Membrane becomes depolarised, allowing opening of voltage-dependent calcium channels

Rapid influx of calcium

Triggers insulin exocytosis.

Question 20

What is stored together with insulin in secretory granules and released in equimolar concentration

Answer 20

C-peptide

Proinsulin contains alpha and beta chains of insulin, joined by the C-peptide.
Presence implies endogenous insulin production

Question 21

Biphasic insulin release

Answer 21

B-cells sense rising glucose and aim to metabolise it

1st phase = Rapid release of stored products
2nd phase = slower release of newly synthesised hormone

Question 22

Insulin action in muscle and fat cells

Answer 22

GLUT4 insulin receptor is a high affinity large transmembrane glycoprotein

Mechanisms not fully understood.

Causes exocytosis of GLUT4 vesicles, increasing glucose transporter in cell membrane and rapid uptake of glucose.

Question 23

What is a short-term glucose buffer

Answer 23

Liver glycogen

(Glucose concentrations in portal venous blood can eaily reach 20mM after a meal.
Much of this removed by liver
Insulin allows peripheral muscle and adipose tissue to take up glucose from the circulation
Some of the surplus glucose is stored locally as glycogen, but it is mostly converted into fats)

Question 24

Where are glucose sensors located?

Answer 24

Pancreatic islets
Medulla, hypothalamus and carotid bodies

Inputs from eye, nose, taste buds

Sensory cells in gut wall (incretins)

Question 25

Do you get a greater insulin response following intravenous or oral intake of glucose?

Answer 25

Oral.

Due to gut hormones called incretins stimulate insulin release

Question 26

Postprandial glucose levels are regulated by what 3 mechanisms?

Answer 26

Insulin, glucagon and gastric emptying

Question 27

In the fasting state, all glucose comes from…

Answer 27

the liver

(breakdown of glycogen, gluconeogenesis)

Question 28

Pathway when blood sugar is low and then high

Answer 28

Stimulates release of glucagon

Glucagon acts on liver to convert glycogen to glucose and glucose to be made from lactic acid and amino acids.

Glucose released from liver raises blood glucose to normal
Hyperglycaemia inhibits release of glucagon.

Stimulate release of insulin.

Insulin acts on cells so blood glucose levels fall.

Hypoglycaemia inibits release of insulin.

Question 29

Does exercises enhance or prevent glucagon release?

Answer 29

Enhance by increasing sympathetic autonomic division of nervous system

Question 30

What characterises diabetes mellitus

Answer 30

Hyperglycaemia (disorder of carb metabolism)

Question 31

Diabetic ketoacidosis (Type 1)

Answer 31

No insulin made.

Glucose levels in blood are high.

Unrestrained breakdown of other sources of glucose (proteins and fats).
By product is plasma ketones.

Less glucose enters peripheral tissues

Hyperglycaemia and raised plasma ketones

Glycosuria and ketonuria.