Physiology: pancreas

Question 1

ANATOMY
The pancreas has two types of tissues
- What is the exocrine tissue?
- What is the endocrine tissue?

Answer 1

Exocrine tissue: acinar cells (and duct cells)
Endocrine tissue: Islets of Langerhans

Question 2

ANATOMY
What are the 4 cell types in the Islets of Langerhans?

–> How to remember?

Answer 2

Beta cells (60%): secrete insulin and amylin

Alpha cells (25%): secrete glucagon

Delta cells (10%): secrete somatostatin

PP cells (smaller numbers): secrete pancreatic polypeptide, which has an unknown role

–> In diabetes, you get a bad PP

Question 3

ANATOMY
The Islets of Langerhans are well vascularised.

Describe their venous drainage; implications for hormone concentrations

Answer 3

Hormones enter the pancreatic vein and then travel to the hepatic portal vein

Pancreatic enzymes have higher concentrations in the liver versus peripheral tissues

Question 4

INSULIN
- Two stimuli for insulin secretion

Answer 4

Increased BGLs
Amino acids

Question 5

INSULIN
Role of beta cells in regulating insulin secretion?

Answer 5

ATP binds to K+ channels, closing them –> depolarisation

This depolarisation leads to opening of voltage gated Ca2+ channels –> Ca2+ influx –> exocytosis of insulin granules

Question 6

INSULIN
Describe how insulin binds to receptors on target cells

Answer 6

Insulin binds to the alpha subunit of insulin receptor

This triggers the autophosphorylation of the beta subunit, which induces tyrosine kinase activity

Phosphorylation events mediate the cellular impacts of insulin

Question 7

INSULIN
Effects
- What impact does it have on BGLs?
- What 3 tissues does it act on?

Answer 7

Increased glucose uptake and utilisation; and storage.
Acts to decreased BGLs overall –> restoring them to normal levels

Liver, skeletal muscle, adipose tissue

Question 8

INSULIN
Effects
- Fill in this table

Answer 8

Question 9

GLUCAGON
- What are its two stimuli?

Answer 9

Decreased BGLs

Amino acids (eg. protein rich meal)

Question 10

GLUCAGON
Describe its effects

Answer 10

Stimulates glycogenolysis and GNG in the liver —> increased BGLs (restored to normal levels)

Question 11

Amino acids stimulate the release of both insulin and glucagon.
Impact on BGL?

Answer 11

Minimal impact on BGLs - as it doesn’t change the insulin : glucagon ration much

Question 12

DIABETES MELLITUS
Glucose tolerance testing in heatlhy person vs person with type I diabetes?

Answer 12

Question 13

DIABETES
What are the three cardinal symptoms of diabetes?

Answer 13

Polyuria - impaired glucose reabsorption –> glucose builds up in kidney tubules –> creates osmotic pressure which drives water into the tubules

Polydipsia - from water loss due to polyuria

Polyphagia - cells cannot take up glucose and are “starving”

Question 14

DIABETES
What are the microvascular and macrovascular complications of diabetes?

Answer 14

Microvascular complications: neuropathy, retinopathy, nephropathy

Macrovascular complications: CVD

Question 15

DIABETES
What occurs when insulin isn’t produced