Water, glucose and hunger control

Question 1

What detects high/ low blood osmolality?

Answer 1

osmoreceptors in hypothalamus

Question 2

What is the response to high blood osmolality detection, where does this occur?

Answer 2

ADH secretion from posterior pituitary

Thirst stimulation

Question 3

What effect does ADH have?

Answer 3

increased resorbtion of H20 from urine into blood in kidneys

Question 4

What happens in response to plasma glucose increasing?

Answer 4

• pancreas releases insulin
• this activates GLUT4 receptors to uptake more glucose into tissues
• also glycogenesis in liver
• blood glucose levels decrease to normal

Question 5

What happens in response to plasma glucose decreasing?

Answer 5

• glucagon secretion from pancreas
• stimulates glycogenolysis, and gluconeogenesis
• plasma glucose increases

Question 6

Where is the appetite control center?

Answer 6

the acurate nucleus of the hypothalamus

Question 7

What neurotransmitters are released by the stimulatory primary neurones of the acurate nucleus which stimulate hunger?

Answer 7

• Neuropeptide Y (NPY)

- agouti- related peptide (AgRP)

Question 8

What neurotransmitters are released by the inhibitory primary neurones which promote satiety?

Answer 8

• pro- opomelancortin (POMC) breaks down into a- MSH which acts on MC4 receptor
• B- endorphine

Question 9

What effect do neurotransmitters released from primary neurones of the acurate nucleus have?

Answer 9

• they act on secondary neurones

- which go on to modulate feeding behaviour

Question 10

What hormones act on the primary stimulatory neurones of the acurate nucleus, what effect do they have and where are they released from?

Answer 10

• PYY from small intestine is released when full and so inhibits the stimulatory neurone
• Ghrelin from the stomach is released when not full and so stimulates to it produce hunger
• leptin from adipose tissue is released when stores are full and so inhibits the stimulatory neurone

Question 11

What hormones act on the primary inhibitory neurone of the acurate nucleus?

Answer 11

• leptin stimulates it to promote statiety

- insluin has minor stimulatory effect

Question 12

What effect does amylin secretion from the pancreas have?

Answer 12

• supresses appetite
• decreases glucagon secretion
• slows gastric emptying
• theyre not sure how but trialling it as a treatment for type 2 diabetes