9 - Insulin counter-regulatory hormones

Question 1

What is the function of glucagon

Answer 1

Reciprocal response to insulin

causes glucose release when glucose levels are too low

Question 2

What are levels of glucagon at a meal

Answer 2

120pg/ml

Question 3

How many AA is glucagon

Answer 3

29aa

Question 4

what are the precursors of glucagon

Answer 4

Preproglucagon –> proglucagon –>glucagon

Question 5

What blood glucose levels stimulate glucagon secretion

Answer 5

80-90mg/100mg

Question 6

What else can stimulate glucagon release

Answer 6

increased levels of arginine and alanine in blood

glucagon converts AA –> Glucose

Question 7

What sort of receptor is the glucagon receptor

Answer 7

GPCR

Question 8

What occurs when the glucagon receptor is activated

Answer 8

Glucagon activates adenylate cyclase –> increases cAMP –> Increases PKA –> phosphorylase kinase –> increased glycogenolysis and gluconeogenesis and decreased glycogenesis and glycolysis

Question 9

Gluconeogenesis

Answer 9

o Increased uptake of a.a by amino acids
o Inhibition of PFK-1 via F2,6 BP (mediated by PKA)
o Inhibition of pyruvate kinase (mediated by PKA)

Question 10

What is lipolysis

Answer 10

o Breaking down of triglycerides

o Mediated by hormone sensitive lipase which is activated by glucagon/PKA

Question 11

What are fatty acids used for

Answer 11

ATP

Question 12

How are fatty acids transported into the mitochondria

Answer 12

Carnitine shuttle
 CPT-1 inhibited by insulin and activated by glucagon
 CPT-1 used in carnitine shuttle
 Once inside, fa –> acetyl coA –> ketone bodies

Question 13

What inhibits glucagon and how

Answer 13

SS + Insulin
activate phosphodiesterase
Breaks down cAMP –> 5’AMP
Cannot signal the glucagon

Question 14

Catecholamines on glucagon

Answer 14

Short term
= released in response to hypoglycaemia and stress
Synthesised from phenylalanine and tyrosine

Question 15

Adrenaline

Answer 15

Inhibits insulin
o Stimulates glycogenolysis in the liver and muscle
o Stimulates glucagon release
o Increases lipolysis in adipose tissue

Question 16

Cortisol effect

Answer 16

	Enhances gluconeogenesis
	Inhibits glucose uptake
	Stimulates muscle proteolysis
	Adipose tissue lipolysis
	All of which rapidly mobilises other sources of metabolites from the body. OTHER THAN NEURON PROTEINS AND CONTRACTILE PROTEIN.

Question 17

Growth hormone

Answer 17

o	Similar to glucagon
	Increase HSL + lipolysis
	Increase B oxidation
	Reduce glucose uptake
	Increase VLDL secretion in Liver
	Increase uptake of LDL IDL and HDL in Liver

Question 18

Thyroid hormone

Answer 18

Enhance glucose uptake in muscle

increase hepatic gluconeogenesis