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ENDO > Wk 8 > Flashcards

Wk 8 Flashcards

Endocrine Function of the Pancreas and Diabetes Mellitus

1
Q

What is the role of the Islets of Langerhans?

A

Endocrine cells that secrete pancreatic hormones.

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2
Q

What are the five cell types of the Islets of Langerhans and what do they secrete?

A
  1. Alpha cells - secrete glucagon
  2. Beta cells - secrete insulin, amylin
  3. Delta cells - secrete somatostatin
  4. PP cells - pancreatic polypeptide
  5. Epsilon cells - ghrelin
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3
Q

How are the hormones regulated?

A

Somatostatin - inhibits alpha & beta (glucagon & insulin)

Insulin - inhibits alpha (glucagon)

Glucagon - stimulates beta (insulin)

Ghrelin - inhibits alpha and beta (glucagon & alpha)

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4
Q

What are the effects of insulin of carbohydrate metabolism?

A

Promotes uptake and storage of glucose.

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5
Q

What are the effects of insulin of protein metabolism?

A

Promotes protein synthesis.

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6
Q

What are the effects of insulin of fat metabolism?

A

Promotes fat storage.

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7
Q

What is the biosynthesis pathway of insulin (beta cells)?

A

Preproinsulin –> proinsulin –> insulin & C-peptide

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8
Q

What is C peptide used for?

A

Used as a useful marker of beta-cell function (more C peptide = greater insulin secretion in blood).

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9
Q

What are the steps for the process of insulin secretion?

A
  1. Glucose transported by facilitated diffusion into beta cells via GLUT-2
  2. Increase in glucose conc. (beta cells)
  3. Increase in glucose metabolism (beta cells)
  4. Increase in ATP:ADP ratio within cell
  5. K+ channels close (depolarises cell)
  6. Ca2+ channels on membrane open
  7. Influx of extracellular Ca2+ ions
  8. Insulin released by exocytosis
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10
Q

What are the three main effector organs for insulin?

A
  1. Liver cells
  2. Muscle cells
  3. Adipose tissue
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11
Q

What is the role of insulin in the liver cells?

A
  • increased metabolism of glucose as fuel
  • increased storage of glucose as glycogen
  • stimulates hepatic protein synthesis
  • inhibits protein breakdown
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12
Q

What is the effect of insulin in the muscle cells?

A
  • increased glucose uptake through GLUT4
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13
Q

What is the effect of insulin in adipose tissue?

A
  • stimulates glucose uptake in adipose tissue via GLUT 4
  • increases glucose storage as a triglyceride within the adipocytes
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14
Q

What is glucagon?

A
  • secreted by alpha cells (Islets of Langerhans)
  • antagonises insulin to increase blood glucose (causes hyperglycemia)
  • target organ is the liver
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15
Q

What regulates glucagon?

A

Stimulated - hypoglycemia (low BG)
Inhibited - hyperglycemia (high BG)

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16
Q

What are the actions of glucagon?

A
  • breakdown of liver glycogen
  • increases gluconeogenesis
  • inhibits storage of triglycerides
  • increases fatty acids (ketogenic)
17
Q

What are the actions of glucagon in the liver?

A
  • increased glycogenolysis (breakdown of glycogen)
  • increased gluconeogenesis
    (formation of glucose from non-carbohydrates)
18
Q

What are the actions of glucagon in the adipose tissue?

A
  • increased lipolysis (breakdown of fats)
19
Q

What is the mechanism of action of glucagon?

A

Glucagon activates G protein stimulating adenylate cyclase (cAMP pathway).

20
Q

What are incretins?

A

Digestive tract hormones that increase insulin secretion from beta cells in pancreas.

21
Q

What are the two major incretins?

A
  1. Glucagon-like peptide 1 (GLP-1)
  2. Glucose-dependant insulinotropic polypeptide (GIP)
22
Q

What is the main action of GLP-1?

A

Stimulation of glucose-dependant insulin release from the pancreatic islets.

23
Q

What is the main action of GIP?

A

In fasting state - enhances glucagon activity (wants to increase BG as it is low).

During hyperglycemia - maintains BG level.

24
Q

What are the hormones that regulate blood glucose conc?

A

Insulin & Glucagon

Fed state:
- insulin dominates (lowers BS)
Fasting state:
- glucagon dominates (raises BS)

25
Q

What is diabetes mellitus?

A

A condition where there is too much glucose in the blood.
(sweet urine).

26
Q

What is type 1 diabetes mellitus?

A

Beta cell destruction leading to insulin deficiency (can’t make insulin).

27
Q

What is type 2 diabetes mellitus?

A

A progressive insulin secretory defect on the background of insulin resistance (makes insulin but due to an insulin resistance it is ineffective).

28
Q

What are symptoms of type 1 diabetes mellitus?

A
  • weight loss
  • young age
  • ketonuria (high levels of ketones in urine)
  • severe symptoms (life-threatening)
29
Q

What are symptoms of type 2 diabetes mellitus?

A
  • usually overweight/obese
  • no ketoacidosis
  • minimal symptoms
  • c-peptide detectable
30
Q

What are common symptoms of diabetes mellitus?

A
  • polyphagia (always being hungry)
  • polydipsia (excessive thirst)
  • polyuria (frequent urination)

ENDO (10 decks)

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