Pancreas physiology

Question 1

What is the difference between endocrine and exocrine glands?

Answer 1

Endocrine - secretes products directly into the blood stream (ductless gland)

Exocrine - secretes products into a duct by which it travels to its destination

Question 2

What is the function of exocrine region of the pancreas?

Answer 2

Secretes pancreatic fluid that contains digestive enzymes that pass to the small intestine

Question 3

What regulates the release of digestive exocrine hormones from the pancreas?

Answer 3

CCK and secretin
which are hormones secreted by the stomach and duodenum in response to distention and food
Vagus nerve to a small extent

Question 4

Name the exocrine substances of the pancreas.

Answer 4

Amylase, lipase, proteases (tripsinogen & proteolytic enzymes activated in duodenum), HCO3- to neutralise chyme.

Question 5

Describe how exocrine secretions get from their origin to their destination.

Answer 5

Produced in acini
Secreted into lumens of acini
Secretions accumulate in interlobular ducts
Which drain into main pancreatic ducts
Which drains into duodenum and aids digestion

Question 6

What is the function of the endocrine region of the pancreas?

Answer 6

Secretes important hormones into the blood

Question 7

Name the cells that make up islets of Langerhans.

Answer 7

Alpha
Beta
Delta
Gamma

Question 8

What do alpha cells do?

Answer 8

Detect a decrease in blood glucose

So they secrete glucagon into blood

Question 9

What does glucagon do?

Answer 9

Binds to liver receptors
Which stimulates glycogenesis (glycogen>glucose)
And production of enzymes needed for gluconeogenesis (Amino acids>glucose)

Ultimately results in increase in blood glucose!

Question 10

What do beta cells do?

Answer 10

Detect and increase in blood glucose

So they secrete insulin into the blood

Question 11

What does insulin do?

Answer 11

Bind to receptors on cells which changes the shape of GLUT4 channels

Which results in increased uptake of glucose by cell
Increased glycogenesis (glycogen synthesis)
Increased glycolysis (glucose to pyruvate)

Results in lower blood glucose

Question 12

What do delta cells secrete?

Answer 12

Somatostatin - which regulates alpha and beta cell function

Question 13

What do gamma cells secrete?

Answer 13

Pancreatic polypeptide - which regulates pancreatic secretion activities

Question 14

Describe the blood supply to the endocrine region of the pancreas.

Answer 14

Very good

Most endocrine cells are in direct contact with blood vessels

Question 15

Name the endocrine hormones of the pancreas.

Answer 15

Insulin, glucagon and somatostatin

Question 16

Describe briefly how insulin is secreted. Describe the 2 phases!

Answer 16

Insulin is stored in the pancreas in granules. It is release when metabolic signals are received.

Beta cells release insulin in two phases

1. FAST - rapid release in response to increased blood sugar
2. SLOW - released slowly triggered independently of sugar

Question 17

What are the main destinations of insulin?

Answer 17

Liver
Fat cells
Muscle cells

Question 18

What does insulin do when it gets to its destination?

Answer 18

Insulin gets to a muscle, fat or liver cell via the blood stream

It binds with insulin receptors on the cell membrane - which triggers the cell to display GLUT4 channels on the cell membrane

GLUT4 channels allow the excess glucose to go from the blood to inside cells for storage

Question 19

What is the body’s response to raised glucose?

Answer 19

Insulin secreted from pancreas into blood
Insulin allows glucose to be absorbed by body cells
Liver coverts glucose into glycogen