Insulin counter-regulatory hormones Flashcards Preview

MET2 > Insulin counter-regulatory hormones > Flashcards

Flashcards in Insulin counter-regulatory hormones Deck (16):
1

What are the key properties of glucagon?

29 amino acid peptide
made by alpha cells in islets of langerhans in the pancreas

2

How is glucagon formed?

preproglucagon -> proglucagon -> glucagon

3

In what conditions are glucagon secreted?

low blood glucose levels
increase amino acid levels (arginine and alanine)
exercise

4

What is the glucagon receptor like?

7 fold transmembrane GPCR receptor

5

How does glucagon signalling work?

glucagon binds to the GPCR receptor -> activates cAMP -> protein kinase A activation -> phosphorylates phosphorylase kinase -> glycogen phosphorylase converts glycogen to glucose-6-phosphate

6

What are the effects of glucagon?

glycogenolysis
amino acid uptake
gluconeogenesis
glycolysis inhibited (PFK1 inhibited)
lipolysis (HSL activation)
ketogenesis
beta oxidation of fatty acids (CPT-1 activation)

7

What happens in prolonged fasting?

oxaloacetate replaces amino acids for gluconeogenesis
formation of acetoacetate (ketone) inhibited by glucagon so don't get excess cholesterol or TGA

8

What are the adrenocortical hormones?

Steroid hormones - mineralocorticoids, glucocorticoids, androgens

9

What are the main examples of catecholamines?

Epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine

10

Where are catecholamines and glucocorticoids made?

- adrenal gland medulla (catecholamines)
- adrenal cortex (glucocorticoids)

11

What is the function of catecholamines?

Released during stress/hypoglycaemia
ST: increase glucose and lipid levels
Inhibit insulin secretion, glycogenolysis, glucagon secretion, lipolysis

12

What is the function of glucocorticoids?

Steroid hormone
LT: protein and lipid use

13

What is ACTH, what does it do?

Glucocorticoid
released in anterior pituitary gland causing cortisol secretion which maintains bp and inflammation and:
Allows gluconeogenesis, inhibits glucose uptake, allows muscle proteolysis -> muscle wasting, allows lipolysis

14

Where are growth hormones found and what do they do?

In adipose tissue -> lipolysis, decreased glucose uptake, decreased lipogenesis
In skeletal muscle -> decreased glucose uptake, increased lipoprotein lipase activity
Liver -> increased VLDL secretion, HDL and LDL production and secretion

15

What is the function of thyroid hormones?

increase metabolic rate
increase mitochondrial number and activity = increased ATP synthesis
Glucose uptake, glycolysis, gluconeogenesis, insulin secretion
lipids mobilised from adipose so increased fatty acid concentration

16

What do incretins do?

GLP1 increases insulin secretion
slows gastric emptying = satiety
increased B cell function + differentiation