Homeostasis and obesity

Question 1

What are orexigenic and anorerxigenic signals? What do they act on?

Answer 1

orexigenic: hunger (ie fasting, ghrelin)-> AgRP/NPY
anorexigenic: full (ie leptin, insulin) -> POMC
Arcurate hypothalmic nucleus

Question 2

POMC neurons express which neurotransmitter and do what when activated?

Answer 2

α- MSH
Anorexogenic, decrease food intake

Question 3

Describe the leptin signalling pathway, how is it negative feedback?

Answer 3

• Leptin binds, JAK2 phosphorylates sites on the receptor
• STAT3 (TF) binds those sites, is phosphorylated, then sent to nucleus
• pSTAT3 alters transcription of target genes
• SOC3 is induced by pSTAT3 and inhibits phosphorylatioon of the receptor

Question 4

What are normal glucose levels?

Answer 4

2.5-6 mmol/L = normal fasting range
6-10 mmol/L= normal post-meal range

2.5-10 mmol/L blood glucose

Question 5

How does insulin control glucose metabolism?

Answer 5

Insulin binding to its receptor stimulates glucose transporter-4 to let glucose into cells, stored as glycogen
lowers blood sugar

When theres excess pyruvate it gets turned to fatty acids

Question 6

How does glucagon control glucose metabolism?

Answer 6

Glucagon binds its receptor on liver cells, stimulates PKA, which stimulates glycogen breakdown/ glucose synthesis
Raises blood sugar

protein kinase A= PKA

Question 7

A blood glucose test on a type II diabetic would show what?

Answer 7

Blood glucose conc of 140-200 mg/dl

normal= 90-120 mg/dl

Question 8

What does gestational diabetes increase the risk of?

Answer 8

• 3x more likely to hv a baby with a congenital anomaly
• Early birth
• C-section

Question 9

Where is leptin released from?
Where is ghrelin released from?

Answer 9

Leptin= Adipocytes
Ghrelin = stomach