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Gastro > Appetite > Flashcards

Appetite Flashcards

1
Q

What factors determine when we get thirsty?

A

Body fluid osmolality
Blood volume is reduced
Blood pressure is reduced

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2
Q

Q. Which is the most potent stimulus?

A

Plasma osmolality increase is the more potent stimulus – change of 2-3% induces strong desire to drink
Decrease of 10-15% in blood volume or arterial pressure is required to produce the same response

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3
Q

What regulates osmolality and where does it work?

A

Antidiuretic hormone (ADH) or vasopressin

Acts on the kidneys to regulate the volume & osmolality of urine
—-Collecting duct - Aquaporin 2 channel

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4
Q

What happens when plasma ADH is low?

A

A large volume of urine is excreted (water diuresis)

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5
Q

What happens when plasma ADH is high?

A

a small volume of urine is excreted (anti diuresis)

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6
Q

Where is ADH stored?

A

posterior pituitary

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7
Q

What are osmoreceptors? What is their function? Where are they found?

A

Sensory receptors
Osmoregulation
Found in the hypothalamus

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8
Q

Which regions are these receptors found in the hypothalamus?

A

Organum vasculosum of the lamina terminalis (OVLT)

Subfornical Organ (SFO)

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9
Q

How do osmoreceptors work to release ADH>

A
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10
Q

How is thirst decreased? What receptors are involved? How is thirst completely satisfied?

A

-Thirst is decreased by drinking even before sufficient water has been absorbed by the GI tract to correct plasma osmolality
-Receptors in mouth, pharynx, oesophagus are involved
-Relief of thirst sensation via these receptors is short lived
-Thirst is only completely satisfied once plasma osmolality is decreased or blood volume or arterial pressure corrected.

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11
Q

What are changes in blood pressure and volume controlled by?

A

The renin-angiotensin-aldosterone system

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12
Q

How does the renin-angiotensin-aldosterone system work?

A
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13
Q

What does a reduction in fat mass increase?

A

Food intake and reduces energy expenditure

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14
Q

What does adipose tissue expansion reduce?

A

Food intake and increases energy expenditure

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15
Q

What happens in overfed state during weight homeostasis?

A
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16
Q

What happens in underfed state during weight homeostasis?

A
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16
Q

What information does the hypothalamus take in during appetite regulation?

A
17
Q

What does the hypothalamus control in appetite regulation?

A

-Food intake
-Energy expenditure

18
Q

What is the appetite stimulating peptide?

A

Orexigenic

19
Q

What is the appetite suppressive peptide?

A

Anorectic

20
Q

What is the arcuate nucleus’s function?

A

Synthesises information leading to the production of orexigenic and anorectic neuropeptides

21
Q

Where is the arcuate nucleus?

A

Basal medial aspect of hypothalamus
Surrounding third ventricle

22
Q

Where does the arcuate nucleus pass information to?

A

Paraventricular nucleus and this has neurones that terminate in the posterior pituitary

23
Q

What does the lateral hypothalamus do?

A

Produces orexigenic neuropeptides

24
Q

What do AGRP neurones do?

A

Inhibits POMC

25
Q

What mutation can cause morbid obestiy?

A

POMC deficiency and MC4-R mutations cause morbid obesity.

26
Q

What is involved in the melanocortin system?

A
27
Q

What other brain regions send signals that are involved in appeitite?

A
28
Q

Explain the Adipostat mechanism

A
29
Q

Where is leptin made and where is it circulating?
Where does it act and what does it do?

A

Made by adipocytes in white adipose tissue and enterocytes
Circulates in plasma.
Acts upon the hypothalamus regulating appetite (intake) and thermogenesis (expenditure).

30
Q

Explain the systemic effect of leptin?

A

Low when low body fat

High when high body fat

Replacement in the ob/ob mouse decreases weight

Hormone that decreases food intake and increases thermogenesis

31
Q

Explain leptin resistance

A

Leptin circulates in plasma in concentrations proportional to fat mass

Fat humans have high leptin

Obesity due to leptin resistance- hormone is present but doesn’t signal effectively

Leptin is ineffective as a weight control drug.

32
Q

Explain the mechanism of leptin

A
33
Q

Why do we feel less hungry after a meal?

A

Hormonal Signal from the gut

34
Q

Where are gastrointestinal hormones secreted from?
What are their functions?

A

Enteroendocrine cells in the stomach, pancreas & small bladder
Control various functions of digestive organs

35
Q

What does Ghrelin do?

A

Stimulate appetite, increases gastric emptying

36
Q

What does Peptide YY do?

A

Inhibits food uptake

37
Q

When is Ghrelin highest?
What does it do?
What neurones does it modulate?

A
38
Q

Why is PYY not a successful weight loss medication?

A

As the consequences are intolerable - nausea and vomitting

39
Q

What is PYY?
Where is it released?

A
40
Q

What are the consequences of obesity?

A

Depression
Sleep apnoea
Bowel cancer
Osteoarthritis
Gout
Stroke
Myocardial infarction
Hypertension
Diabetes
Peripheral vascular disease

Gastro (6 decks)

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