Physiology: pancreas Flashcards

1
Q

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

A

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

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2
Q

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

–> How to remember?

A

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

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3
Q

ANATOMY
The Islets of Langerhans are well vascularised.

Describe their venous drainage; implications for hormone concentrations

A

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

Pancreatic enzymes have higher concentrations in the liver versus peripheral tissues

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4
Q

INSULIN
- Two stimuli for insulin secretion

A

Increased BGLs
Amino acids

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5
Q

INSULIN
Role of beta cells in regulating insulin secretion?

A

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

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

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6
Q

INSULIN
Describe how insulin binds to receptors on target cells

A

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

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7
Q

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

A

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

Liver, skeletal muscle, adipose tissue

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8
Q

INSULIN
Effects
- Fill in this table

A
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9
Q

GLUCAGON
- What are its two stimuli?

A

Decreased BGLs

Amino acids (eg. protein rich meal)

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10
Q

GLUCAGON
Describe its effects

A

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

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11
Q

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

A

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

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12
Q

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

A
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13
Q

DIABETES
What are the three cardinal symptoms of diabetes?

A

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”

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14
Q

DIABETES
What are the microvascular and macrovascular complications of diabetes?

A

Microvascular complications: neuropathy, retinopathy, nephropathy

Macrovascular complications: CVD

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15
Q

DIABETES
What occurs when insulin isn’t produced

A
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