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Physiology > Pancreas > Flashcards

Pancreas Flashcards

1
Q

Exocrine

A

secretions get dropped into a duct and the duct takes it to where it needs to go

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2
Q

endocrine

A

dump secretions into blood and they go everywhere

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3
Q

Anatomy of pancreas

A
  • Head- mostly exocrine
  • body- mostly endocrine
  • Tail
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4
Q

Islets of Langerhans

A

Group of Endocrine cells

  • alpha- releases glucagon (18-20% of endocrine cells)
  • beta- releases insulin (73-75% of endocrine cells)
  • delta- somatostatin (4-6% of endocrine cells)
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5
Q

What stimulates insulin secretion?

A

glucose

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6
Q

What inhibits glucagon secretion?

A

insulin

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7
Q

What is insulin composed of?

What is it synthesized from?

A
  • Insulin is a peptide hormone
    • composed of A and B chain joined by disulfide bonds
  • synthesis: preproinsulin→proinsulin→insulin + c peptide
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8
Q

What is the half life of insulin?

where is it metabolized?

A

3-8 minutes

degraded by liver and kidney

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9
Q

What does C-peptide measurement indicate?

Half life of C-peptied?

A

C-peptide is measured as an index of endocrine capacity of the pancreas

about 15 minutes

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10
Q

What is the process for insulin secretion?

A
  • glucose enters beta cell through GLUT2 transporter by diffusion
  • glucose goes through glycolysis, turning ADP into ATP
  • ATP is the ligand for the K channel. K channel closes.
    • cell starts to depolarize with K channel closed
  • Once cell depolarizes to threshold of voltage gated calcium channel, Ca channel opens and Ca rushes in
  • Calcium causes release of insulin vesicles and the making of more insulin
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11
Q

When is glucagon released?

What is the target organ for glucagon?

A

when insulin levels are low

Target: liver

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12
Q

How does glucagon work when it gets to the liver?

A
  • Glucagon binds to a GCPR (Gs)
  • GPCR stimulates adenylyl cyclase and increases cAMP and thus PKA to phosphorylate target proteins
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13
Q

How does insulin get glucose into the cell?

A
  • insulin binds to the GPCR
  • GLUT4 transporter is recruited to the plasma membrane and facilitates glucose into the cell along with amino acids, K, Mg, and Phosphate.
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14
Q

GLUT1

A

widely distributed; gets glucose into cells all over

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15
Q

GLUT2

A
  • found on Beta cells, kidney, intestines, liver
  • low affinity, high capacity
  • does not rely on insulin to transport glucose
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16
Q

GLUT3

A

supplies neurons with glucose

17
Q

GLUT4

A
  • Found in muscle and fat
  • depends on insulin to get glucose into the cells
18
Q

GLUT5

A

Intestines

can also transport fructose

19
Q

SGLT1, SGLT2

A

Sodium dependent glucose transporters

found in Intestines and Kidney

Na-glucose co-transporters

20
Q

Effects of insulin

A
  • decreased appetite
  • decreased glucagon
  • increased glucose uptake by muscles and fat
  • increased glycolysis
  • increased glycogen synthesis
  • increased triglyceride synthesis
  • increased amino acid uptake
  • increased protein synthesis
21
Q

Effects of lack of Insulin

primarily because of glucagon

A
  • increased appetite
  • increased glucagon
  • decreased glucose uptake by muscle and fat
  • increase blood glucose
  • increase gluconeogenesis
  • increased lipolysis
  • increased protein breakdown
  • increase glycogenolysis
  • Increase ketone body production
  • decrease protein synthesis
22
Q

What happens to:

insulin

glucagon

free fatty acids

blood glucose

liver glycogen

blood ketone bodies

As hours of starvation increases?

A
23
Q

Type 1 Diabetes mellitus

A

Autoimmune destruction of Beta cells

about 10% of diabetes

24
Q

Type 2 diabetes mellitus

A

Insulin resistance

about 90%

25
Q

Mature onset diabetes of youth (MODY)

A
  • Genetic defect in insulin production or release
    • insulin will help, but not as much as oral meds that increas K channel sensitivity
  • about 2% of young diabetics
26
Q

Gestational diabetes

A

Any diabetes identified during pregnancy

*precursor to actual diabetes

27
Q

How does Type 1 diabetes happen?

A
  • Pancreatic Beta cells get destroyed.
    • person gets some kind of bug
    • body makes antigen
    • proteins coming off the beta cell matches antigens too closely
    • Beta cell gets attacked by immune system
    • body continues to make the beta cells, but they all get killed by the antibodies
28
Q

lipolysis

A

breakdown of fat

29
Q

glycogen synthesis

A

liver making glycogen from glucose

30
Q

gluconeogenesis

A

making glucose from non carbohydrates; lactate, glycerol, amino acids

*Important to get glucose to the brain. Everything else can survive on ketones. Happens in liver.

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