Control

Question 1

Leptin, what is it?

Answer 1

hormone that provides long term appetite regulation

Question 2

Where is the arcuate nucleus found?

Answer 2

Base of brai

Question 3

What is ghrelin?

Answer 3

peptide hormone that regulates short-term appetite control by promoting eating behaviours.
‘hunger hormone’ and is secreted from cells in the stomach in increasingly higher quantities in the build up to a meal

Question 4

What is peptide YY

Answer 4

Peptide hormone that regulates short-term appetite control by suppressing eating behaviours.

Question 5

What do NPY/Agrp neurons do? Where are they located

Answer 5

Stimuate food intake and are located medially

Question 6

What do POMC neurones do?

Answer 6

Inhibit food intake and are located more laterally

Question 7

What is POMC

Answer 7

Long peptide that can be cleaved in many ways for many different purposes

Question 8

What is the key site for axons of neurones what’s cell bodies lie in arcuate nucleus for appetite

Answer 8

Paraventricular nucleus

Question 9

What does Agrp; POMC form?

Answer 9

Alpha melanocyte stimulating hormone - alpha MSH

Question 10

What does alpha MSH do?

Answer 10

Bind to receptors in paraventricular nucleus eg melanocortin 4 receptor MC4R which is involved in regulation of food intake, and receptor when activated decreases food intake behaviours

Question 11

What are the actions of alpha MSH and Agrp to MC4R

Answer 11

alpha-MSH binds to MC4R, which responds by reducing food intake behaviours
Agrp binds to MC4R and competitively blocks the satieting signal (i.e. I’m full and I don’t need to eat) from α-MSH. This causes an increase in food intake behaviours

Question 12

What does POMC deficiency and MC4R mutation cause

Answer 12

Morbid obesity

Question 13

Where is leptin secreted?

Answer 13

Cells in white adipose tissue

Question 14

What does leptin do? What does it bind to?

Answer 14

Receptors in the hypothalamic circuits and stimulates anorexigenic behaviours (i.e. suppresses appetite).

Question 15

What is leptin resistance associated with

Answer 15

Obesity

Question 16

What does ghrelin do and what does it bind to?

Answer 16

binds to hypothalamic receptors and increases the perception of hunger and the urge to eat.

Question 17

Where is peptide YY secreted?

Answer 17

from cells in the ileum and colon in response to a meal.

Question 18

What does peptide YY bind to? What does it do?

Answer 18

PYY3-36 binds to hypothalamic receptors and reduces the perception of hunger and the urge to eat.

Question 19

What are the sensing organs for solute concentration?

Answer 19

Osmoreceptors
Found in brain adjacent to structures with incomplete blood brain barrier - principally hypothalamus, within the OVLT and SFO regions

Question 20

What does vasopressin do

Answer 20

To insert aquaporin-2 channels into the collecting duct of renal nephrons to increase water reabsorption
To stimulate vasoconstriction
which conserves blood volume and increase BP
Stimulate thirst

Question 21

Where is vasopressin produced and released?

Answer 21

Produced in the hypothalamus and released from the posterior pituitary gland.

Question 22

What do osmoreceptive cells do in response to changes in osmolarity?

Answer 22

affect the firing rate of these cells, which will adjust the basal level of ADH being secreted. Increased ADH secretion will lead to water retention (and a decreased osmolality).

Question 23

How can thirst be satisfied?

Answer 23

Presence of water in the GI tract can quench thirst, for a short period of time at least - receptors in the upper GI tract (mouth to oesophagus) - short term feedback
Once the original stimulus (osmolality or blood pressure) has been corrected, then the perception of thirst is no longer felt - long term feedback

Question 24

What are the 5 primary effects of angiotensin II

Answer 24

It binds to receptors on vascular smooth muscle cells to stimulate VASOCONSTRICTION
It upregulates activity of the sympathetic nervous system - VASOCONSTRICTION
It stimulates ALDOSTERONE SECRETION, which increases NA+ REABSORPTION in nephron - osmotic gradient for water reabsorption
It directly influences sodium reabsorption, causing water reabsorption
It stimulates ADH RELEASE and stimulates thirst

Question 25

Where is angiotensinogen produced?

Answer 25

Liver

Question 26

Where is angiotensinogen converted to angiotensin I

Answer 26

Kidney

- renin secreted in response to low BP

Question 27

How is Angiotensin I converted to angiotensin II? What cells express the enzyme

Answer 27

Angiotensin converting enzyme ACE

Expressed on vascular endothelial cells of pulmonary and renal microvessels