Control of blood glucose & endocrine pancreas Flashcards

1
Q

How does glucose get into cells?

A

→ Secondary active transport
→ SGLT 1
→ Sodium transports glucose into the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does glucose get reabsorbed in the kidney?

A

→ SGLT 1 and SGLT2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is GLUT 1 found and in what ranges does it work?

A

→ In the brain + erythrocytes
→ High affinity for glucose
→ Constant uptake at 2-6mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is GLUT 2 found and what is the affinity like?

A

→ liver,kidney,pancreas,gut
→ Low affinity
→ Transport rate increases with glucose concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is GLUT 3 found and what is its affinity?

A

→Brain

→ High affinity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is GLUT 4 found and what is its affinity?

A

→ muscle and adipose tissue
→ Medium affinity
→ Insulin recruits transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does high affinity mean?

A

→ rate of transport does not depend on the concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the islets of Langerhans?

A

→ Clusters of endocrine cells surrounded by an exocrine pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do alpha cells in the pancreas produce?

A

→ Glucagon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do beta cells in the pancreas produce?

A

→ Insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do the delta cells in the pancreas produce?

A

→ Somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the steps for insulin production?

A

1) original transcript is pre-pro insulin
2) Signal sequence is removed ( in RER)
3) Transferred to Golgi apparatus
4) Peptidases break off the C peptide leaving an A and B chain linked by disulfide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

For every mole that is secreted of insulin how many C peptides do you get?

A

one

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the clinical significance of C peptide

A

→ It is inert

→ good index of insulin circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the blood supply of the pancreas?

A

→ Branches of celiac, superior mesenteric and splenic arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the venous drainage of the pancreas?

A

→ Into the portal system

17
Q

Describe the path insulin takes

A

→ Insulin is secreted in circulation
→ drained into portal vein
→ Metabolized by the liver
→ remainder is diluted in circulation

18
Q

Where is the insulin most concentrated?

A

→ in the portal vein

19
Q

Why is C peptide a more accurate index of insulin secretion?

A

→ It is not metabolized by the liver

20
Q

What stimulates the secretion of insulin from Beta cells ?

A
→ rise in plasma glucose 
→ amino acids - arginine
→ Glucagon 
→ Parasympathetic effects
→ Incretin hormones
21
Q

What inhibits insulin?

A

→ Alpha adrenergic receptors

→ somatostatin

22
Q

What stimulates glucagon secretion from alpha cells?

A

→ Amino acids
→ beta adrenergic
→ parasympathetic

23
Q

What inhibits glucagon secretion?

A

→ Plasma glucose
→ Somatostatin
→ Insulin

24
Q

How do beta cells sense a rise in glucose?

A

→ Increase in glucose through the GLUT 2
→ glucose is metabolized into ATP
→ ATP closes a K+/ATP channel
→ Depolarized the cell
→ Activates VG calcium channels
→ rise in iCa stimulates vesicular release of insulin

25
What family is the insulin receptor a part of?
→ Tyrosine Kinase
26
How does the insulin receptor work?
→ Insulin binds | → Starts many protein activation cascades
27
What are the protein cascades activated by the insulin receptor?
→ Translocation of the GLUT 4 transporter to plasma membrane and influx of glucose → Glycogen synthesis → Glyolysis → Fatty acid synthesis
28
What enzyme starts lipogenesis and how?
→ACC starts lipogenesis | → Insulin reduces PKA which inhibits ACC
29
Why is insulin resistance not down to one reason?
→ could be something highly selective | → because there are many intracellular pathways
30
How does the glucagon receptor work?
→ Glucagon binds to its receptor → Adenylate cyclase converts ATP to cAMP → PKA is activated
31
How do insulin counter regulatory hormones work?
→ phosphorylation of enzymes