Endocrine pancreas 2 - Glucagon

Question 1

define incretin hormones?

Answer 1

hormones released by GI tract during digestion - e.g. gastrin, secretin etc.

Question 2

what is glucagon?

Answer 2

peptide hormone produced by alpha cells

also a GLC-mobilising hormone

Question 3

glucagon 1y action?

Answer 3

raise BG

Question 4

half-life of glucagon?

Answer 4

5-10 mins, degraded by liver

Question 5

what is the Glucose counter-regulatory control system and when is it most active?

Answer 5

system involving:
-glucagon
-epinephrine
-cortisol
-GH (growth)
...which opposes insulin
most active during post-absorptive state

Question 6

how does glucagon increase BG?

Answer 6

1) increase glycogenolysis
2) increase gluconeogenesis
3) forms ketones from fatty acids (starvation/diabetes)

Question 7

why is it important that amino acids stimulate both insulin and glucagon?

Answer 7

increase in amino acids (e.g. protein-heavy meal) increases secretion of insulin and uptake of GLC into cells -
need glucagon to balance this as not enough GLC would be present for brain - leading to HYPOGLYCAEMIA

Question 8

Stimuli that promote glucagon release?

Answer 8

BG < 5mM
increased amino acid conc.
sympathetic innervation and epinephrine 
cortisol
stress

Question 9

Stimuli that inhibit glucagon release?

Answer 9

GLC
FFA (free fatty acids)
ketones
insulin 
somatostatin

Question 10

result of increase sympathetic innervation?

Answer 10

increases glucagon and epinephrine, decreases insulin

Question 11

result of increase parasympathetic innervation?

Answer 11

increases insulin (and a little glucagon) and epinephrine

Question 12

role of somatostatin?

Answer 12

to (gradually) inhibit activity of GI tract - slows down movement and absorption

Question 13

what can somatostatin treat?

Answer 13

life threatening diarrhoea

Question 14

effects of exercise on BG?

Answer 14

insulin-independent increase in the number of GLUT-4 transporters
insulin sensitivity of muscle increases
entry of GLC into muscles increases

Question 15

how to GLC get into active and non-active muscle cells?

Answer 15

active:
GLUT4s migrate to membrane without insulin dog GLC uptake is independent
also increases muscle’s sensitivity to insulin

non-active:
insulin binds to receptor THEREFORE GLUT4s go to cell membrane

Question 16

what happens during starvation?

Answer 16

brain and muscles use ketone bodies (converted from excess FAs),
most other tissues use the FAs

Question 17

how does the brain use ketones?

Answer 17

only works if pancreas is functioning properly as ketone body uptake is insulin dependent

Question 18

why is starvation dangerous for diabetics?

Answer 18

diabetics cannot produce enough insulin therefore ketone cannot be used by brain - results in LIFE THREATENING KETOACIDOSIS

Question 19

pH of ketoacidosis?

Answer 19

<7.1

Question 20

how to detect hyperglycaemia?

Answer 20

glucose tolerance test -

Patient ingests glucose load after fasting - [BG] measured - elevation after 2 hours is indicative of diabetes.

Question 21

diabetic complications of hyperglycaemia?

Answer 21

retinopathy
neuropathy
nephropathy
CVD