Endocrinology Flashcards

1
Q

Regarding metabolism in the fed state, where are glucose and AAs transported

A

From intestine to the blood

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2
Q

Regarding metabolism in the fed state, where are dietary lipids transported

A

From the lymphatic system to the blood

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3
Q

What does insulin stimulate

A

Storage of fuels and synthesis of proteins

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4
Q

What is the fuel reserve of a well-fed human

A

161,000 kcal

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5
Q

Energy needed for a 24 hr period

A

1600-6000 kcal

  • sufficient reserves for starvation up to 1-3 months
  • however glucose reserves are exhausted < 1 day
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6
Q

Even under starvation what must the blood-glucose level be above

A

40 mg/100 ml

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7
Q

In prolonged starvation, what is the first priority

A

Sufficient glucose for brain, nervous tissue, RBC

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8
Q

In prolonged starvation, what is the 2nd priority

A

Preserve protein - lipolysis & gluconeogenesis

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9
Q

After 3 days of starvation what do the brain and heart start to do

A

Use ketones as fuel

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10
Q

After several weeks of starvation, what is the major fuel of the brain

A

Ketone bodies

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11
Q

What happens when TAG stores must be used (prolonged starvation)

A

Increase protein degraded

Decrease heart, liver and kidney function

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12
Q

What happens to 1. Glucose 2. Ketone body and 3. FA conc in plasma during starvation

A
  1. Decreases but remains above 3-4 mM
  2. Increases rapidly
    3, Increases slowly
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13
Q

Decreasing order of total body metabolic fuel

A
  1. Fat
  2. Protein
  3. Muscle glycogen
  4. Hepatic glycogen
  5. Circulating nutrients
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14
Q

Decreasing order of circulating fuel

A
  1. glucose

2. TAGs & free FAs

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15
Q

What is the exocrine pancreas associated with

A

Acini - digestion (99%)

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16
Q

What is the endocrine pancreas associated with

A

Islets of Langerhans - control of blood glucose (1%)

17
Q

What do the beta cells of the islets of langerhans release

A

Insulin (see photo)

18
Q

What do the alpha cells of the islets of langerhans release

A

glucagon (see photo)

19
Q

What do the gamma cells of the islets of langerhans release

A

Somatostatin

20
Q

Where are pancreatic polypeptides found and what do they do

A

Found between acinar cells and inhibit pancreatic secretion of fluid

21
Q

What is optimal blood glucose concentration

A

Normal fasting level = 90-100mg/100 mls (5mM)

22
Q

Effect of an increase in glucose on insulin

A

Increased insulin

23
Q

Effect of a decrease in glucose on insulin

A

Decreased insulin

24
Q

Vascularisation of islets

A

Richly vascularised

- 1-2% of pancreas but 10-15% pancreatic blood flow

25
Effect of increasing plasma AAs on insulin
Large increase in insulin
26
Effect of increasing free FAs on insulin
Increase in insulin
27
Effect of increasing Glucagon on insulin
Increase in insulin
28
Effect of increasing GH & GIT hormones on insulin
Increase in insulin
29
What are the islets modulated by
ANS innervation - modulate insulin and glucagon secretion
30
Which has a greater effect - orally administered glucose or IV administered glucose
Orally administered | - glucagon, glucagon derivatives, secretin, cholecystokinin & gastric inhibitory peptide stimulate insulin secretion
31
What is the incretin effect
Gut-derived factors that enhance glucose-stimulated insulin secretion from the islet beta-cell ie a graph re-iterating that oral glucose has a greater effect than IV glucose infusion
32
Where is Glucagon-like polypeptide 1 (GLP-1) synthesised
Within L cells located predominantly in ileum and colon & a lesser number in the duodenum and jejunum
33
What does GLP-1 do
- stimulates insulin secretion - suppresses glucagon secretion - slows gastric emptying - reduces food intake - increases beta cell mass - maintains beta cell function (decreases beta cell apoptosis) - improves insulin sensitivity (muscle) - enhances glucose disposal (decreases glucose production in liver) - Increases cardiac protection and CO - decreases appetite - increases neuroprotection
34
What effect of GLP-1 is preserved in type 2 diabetes
Glucose lowering effects
35
1. Tissue distribution & 2. Special properties of GLUT 1
1. Most cells 2. High capacity Relatively low Km (5mM) => high substrate affinity
36
1. Tissue distribution & 2. Special properties of GLUT 2
``` 1. Liver beta cells hypothalamus basolateral membrane of SI 2. High capacity but low affinity => high Km (15-20mM) Part of the glucose sensor in beta-cells ```
37
1. Tissue distribution & 2. Special properties of GLUT 3
1. Neurons Placenta testes 2. Low Km (1mM) and high capacity
38
1. Tissue distribution & 2. Special properties of GLUT 4
``` 1. Skeletal muscle Cardiac muscle Fat 2. Activated by insulin Km = 5mM ```
39
1. Tissue distribution & 2. Special properties of GLUT 5
1. SI mucosal surface sperm 2. Primarily fructose carrier in intestine