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29 Cards in this Set

  • Front
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1. After a high carbohydrate meal how is the blood glucose level 1, 4, and 8 hours after the meal?
1 hour
-spike in blood glucose levels (highest)

4 hours
-decrease significantly

8 hours
-very low
2. How are insulin levels 1, 4, and 8 hours after a meal?
1 hour
-spike (highest)

4 hours
-decreased significantly

8 hours (over night fast)
-almost no insulin
3. How are glucagon levels 1, 4, and 8 hours after a meal?
1 hour
-very low

4 hours
-still low (slight increase though)

8 hours
-high levles
4. What happens to every molecule of glucose that is consumed?

When glucose is gone what two hormone levels increase and why?
Either use it (growth) or store it

1. Glucagon
-glucose is gone so mobilize and make it

2. Stress hormones
-boost available energy

*Epinephrine is released and on short term basis it increases mobilization of glucose

*Cortisol works on a longer term
5. What is the major anabolic hormone?

What does it do?

Three things...

What does it prevent?
Insulin

1. Increases protein synthesis

2. Increases cell growth

3. Increases fuel storage (glucose as glycogen)

**Prevents breakdown of glycogen
6. What is the first tissue that sees high levels of glucose?

What happens when there is high levels of glucose?
Liver

1. Store it as glycogen
2. Convert it to FA
-exported to adipose tissue a VLDL

3. Muscles can uptake glucose to make ATP and store it as glycogen
7. Other than glucose, what dietary component does insulin affect?
Amino Acids

Stimulate uptake of AA by liver and skeletal muscle to a make proteins

**Net protein synthesis
8. What does the presence of glucagon in the blood signal?

What does glucagon primarily promote?
Absence of dietary glucose

Glucose production via....

1. Glycogenolysis
-glycogen degradation

2. Gluconeogensis
-glucose synthesis from AA and other non-carbohydrate precursors
9. Other than affected glucose what does glucagon do?

What other hormones have an affect on fuel metabolism which oppose those of insulin?
Stimulates mobilization of FA from adipose tissue

Epinephrine and cortisol
10. In the fasting state what is stimulated by glucagon?
1. Glycogen to glucose

2. Amino acids to glucose

3. TG to FA in adipose cell to free FA
-heart and muscles use FA

*brain and RBC cannot use FA
11. What is the purpose of muscle glycogen?

What controls the breakdown of muscle glycogen?
For exercise

**never supplies glucose to blood no matter what

Epiniephrine
12. Where is insulin synthesized?

Where is glucagon synthesized?

Why do they have different function?
β-cells in islets of Langerhans in pancreas

α-cells in islets of Langerhans in pancreas

Have different structure so have different functions
13. How are both insulin and glucagon synthesized?
From prohormones

Insulin
-Larger precursoe (proinsulin)
-Proinsulin is cleaved into mature insulin and C-peptide

Glucagon
-Proglucagon which is cleaved before secretion into blood
14. What happens to β-cells in type I diabetes?

What happens as a result?
Destroyed by an autoimmune response

No insulin is made
15. What is the main trigger for release of insulin?

What does this do to glucagon?
Glucose

Suppresses glucagon release
15. What is the general mechanism of action for both insulin and glucagon?
1. Bind to receptors on cell surface

2. Initiate sequence of intracellular events
**signal transduction

3. Action inside cell but hormone is outside cell
16. During the fasting state, what is the signal transduction by glucagon?

(steps 1-4)
1. Binds to and activates receptor on outer cell surface

2. Receptor activates G protein

3. G protein binds to and activates adenylate cyclase

4. Adenylate cyclase catalyzes ATP to cAMP (intracellular second messenger)
17. During the fasting state, what is the signal transduction by glucagon?

(steps 5-7)
5. cAMP activates protein kinase A (PKA)

6. PKA phosphorylates key regulatory enzymes
*use ATP

7. Phosphorylated protein induces a cellular response
18. How does cAMP activate protein kinase A?

When is the glucaon signal terminated?
It binds to inactive protein kinase A and knocks off the regulatory subunit

PKA now becomes active

When blood glucagon levels fall after a meal
19. In the fed state, what is the signal transduction by insulin?
1. Bind to receptors

2. Auto phosphorylation of receptor at tyrosine residues

3. Subunits also phosphorylate other protein kinases at tyrosine residues
20. Generally, what three things does the binding of insulin to its receptor cause?
1. Phosphorylation of certain proteins (including insulin receptor)

2. Induction or repression of certain genes

3. Stimulates general protein synthesis
21. How does the signal transduction of insulin oppose glucagon?
1. Stimulates phosphodiesterase
-removes cAMP by degrading it to AMP

2. Activates a protein phosphatase
-dephosphorylate enzymes that were phosphorylated in response to glucagon

3. Protein kinase A will also be inactivated
22. Generally speaking, what does insulin do to proteins?

What does glucagon do to proteins?
Dephosphorylate

Phosphorylate
23. What characterizes type II diabetes?

What can cause it?
Insulin resistant

Defects in the insulin receptor itself or in any of the post-receptor steps in insulin signaling
24. How is the signal from a single glucagon molecule highly amplified?
1. Each activated receptor protein activates many G protein molecules

2. Each activated adenylate cyclase molecule generates many cAMP

3. cAMP (enzyme) can act on many of the same subunit

4. Each kinase molecule phosphorylates and activates many molecules of phosphorylase kinase
25. Insulin stimulates glucose transport to which tissues?

How does this happens?
Adipsoe and Muscle

Causes the recruitment of glucose transporters

Binding of insulin to receptors causes vesicles containing glucose transport proteins to move from inside cell to cell membrane
26. Insulin does not stimulate glucose transport into which tissues?

Why?
Liver, Brain, and RBC

Live - produces glucose
-glucose transporters are on cell membrane b/c w/o them couldn't release glucose

Brain and RBC - not insulin dependent b/c need constant glucose
27. Why is glucose transport stimulated to muscles and adipose tissues in the fed state by insulin?

During fasting, why is glucose transport to these tissues lowered?
Provide these tissues w/ glucose needed to rebuild glycogen stores and store excess glucose as fat

Spare glucose for glucose-dependent tissues (brain and RBC)
28. What else mimics the effects of insulin?
Exercise