Fat

Question 1

White Vs Brown adipose tissue

Answer 1

▪️white
-fuel storage
-insulation 
-larger in size
▪️brown
-transfer energy from food into heat 
-lipid utilisation
-smaller in size

Question 2

Leptin

Answer 2

▪️produced by white adipose tissue- ob gene
▪️pro-hormone first, then gets cleaved off to make active version
▪️⬇️food intake- anorexigenic affect (similar to insulin), ⬆️energy expenditure
▪️mutation leads to obesity (recessive)
-hyperphagia, thermogenic defect
▪️receptor ObRb in the hypothalamus

Question 3

Ghrelin and appetite regulation

Answer 3

▪️produced by stomach
▪️orexigenic hormone- increases flood in take
▪️ghrelin receptor (GHS-R) is expressed in brain
▪️ghrelin acts in the brain to stimulate feeding

Question 4

Arcuate nucleus (ARC) in the Hypothalamus

Answer 4

▪️3rd ventricle above median eminence
▪️neutrons expressing orexigenic neuropeptides (hormone)
-neuropeptide Y (NPY)
-agouti-related peptide (AgRP)
▪️neurones expressing anorexigenic neuropeptides
-proopiomelanocortin (POMC)
▪️leptin receptors ObRb expressed in both NPY/AgRP and POMC

Question 5

Paraventricular nucleus (PVN) in hypothalamus

Answer 5

▪️top of 3rd ventricle and AH
▪️converging pathways going in to it and information out
▪️projections from ARC- communicating
▪️releases NPY, seratonin, melanocyte stimulating hormone

Question 6

Ventromedial nucleus (VMH) in hypothalamus

Answer 6

▪️satiety centre
▪️stimulation leads to a ⬇️ in feeding (mimicking leptin)
▪️lesions in the area can lead to over eating and obesity
▪️high amounts of ObRb, leptin receptor

Question 7

POMC Vs AGRP/NPY

Answer 7

▪️when POMC is stimulated it releases alpha melanocyte-stimulating hormone
▪️a-MSH stimulates melanocortin receptors (MCR-4) in PVN
▪️ this helps decrease food intake and increase energy expenditure
▪️insulin, leptin and CCK inhibit AGRP/NPY and stimulate POMC ⬇️food intake
▪️ghrelin stimulates AGRP/NPY to ⬆️food uptake