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Gastro Yr 2 > Appetite > Flashcards

Appetite Flashcards

1
Q

how does the body control thirst?

A

body fluid osmolality increase (most potent stimulus)
Blood vol reduced
Blood pressure reduced

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2
Q

What is ADH?

A

Also known as vasopressin - act on collecting duct in kidney on aquaporin 2 channels - increased water absorption

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3
Q

What is water diuresis?

A

Plasma ADH is low = large vol of water excreted

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4
Q

What is anti diuresis?

A

Plasma ADH is high = small vol of urine excreted

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5
Q

where is ADH stored?

A

posterior pituitary gland

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6
Q

How does the body measure osmolality?

A

Osmoreceptors - v sensitive to changes in blood osmolality

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7
Q

Where are the osmoreceptors found?

A

Organum vasculosum of the lamina terminalis

subfornical organ

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8
Q

How to osmoreceptors lead to ADH release?

A

Plasma more conc = cells shrink = proportion of cation channels increases so membrane depolarises = sends signal to ADH producing cells = ADH released

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9
Q

What affect does ADH have?

A

increased fluid retention

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10
Q

Where are the receptors that detect thirst?

A

mouth/ pharynx/ oesophagus

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11
Q

How is BP/ vol controlled?

A

Drop in BP causes release of renin from kidneys = renin cleaves angiotensin 1 to 2 which has effects on the body to combat

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12
Q

what does angiotensin 2 do?

A

Increases in sympathetic activity leading to vasoconstriction

induces thirst

Release of aldosterone

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13
Q

what does aldosterone do?

A

water retention via sodium/ chloride absorption an potassium excretion

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14
Q

How does weight homeostasis work?

A

central circuit defends against the reduction or rapid expansion of adipose tissue (body wants to go back to original form from the overfed or underfed state)

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15
Q

Where is appetite regulates

A

hypothalamus

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16
Q

Which hormones affect appetite

A

Ghrelin + other gut hormones
LEPTIN

  • neural input from the periphery + other brain regions
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17
Q

What two things contribute to being in an overfed or underfed state?

A

Energy expenditure

Food intake

18
Q

what is the arcuate nucleus?

A

Neurones in medial basal part of hypothalamus - releases appetite suppressive + stimulants

19
Q

what is an appetite suppressive called?

A

Anorectic

20
Q

what is an appetite stimulant called?

A

Orexigenic

21
Q

what is the paraventricular nucleus?

A

Neurones which project to posterior pituitary (where ADH is stored) = release ADH + oxytocin

22
Q

How does the arcuate ncleus have access to peripheral hormones

A

blood brain barrier is incomplete - allows access

23
Q

What are the two populations in the arcuate nucleus

A 
POMC neurone (inhibitory)
NOY/ Agrp neurone (stimulatory)
24
Q

How do NOY/ Agrp neuron stimulate appetite?

A

Increases NPY signalling + reducing POMC signalling via increase of Agrp

25
Q

How does leptin affect neurones in hypothalamus

A

Receptors - leptin inhibits NPY/ AGRP + stimulates POMC (decreased food intake)

26
Q

Explain the melanocortin system?

A

Increase in Agrp in arcuate nucleus inhibits MC4R in paraventricular nucleus/ increase in POMC stimulates MC4R release (MC4T decreases food intake)

27
Q

Which mutations can affect appetite

A

No NPY/ Agrp mutations
POMC deficiency/ MC4R mutations can cause morbid obesity
Not responsible for prevalence of obesity however

28
Q

what is the adipostat mechanism

A

hypothalamus alters neuropeptide to increase/ decrease food intake according to hormone level released by adipose tissue

29
Q

what is leptin?

A

made by adipocytes + enterocytes

Acts on hypothalamus regulating intake + expenditure

30
Q

congenital leptin deficiency

A

Very rare

causes severe obesity very early in life (constantly hungry due to no appetite control)

31
Q

What is the level of leptin when low body fat?

A

Leptin is low

32
Q

What is the level of leptin when high body fat?

A

Leptin is high

33
Q

what is leptin resistance

A

leptin doesn’t signal effectively so appetite + thermogenesis control does not work

34
Q

Leptin as a drug?

A

DOES NOT WORK as a weight control drug

35
Q

Why do we feel less hungry after a meal?

A

Gastrointestinal hormones like ghrelin and peptide YY

36
Q

Where are gastrointestinal hormones released

A

Gastrointestinal hormones secreted by enteroendocrine cells in stomach/ pancreas/ small bowel

37
Q

what does ghrelin do?

A

Increases appetite by increasing gastric motility + acid secretion

38
Q

how do concentrations of ghrelin change in a day?

A

increases two fold before meal times/ follows diurnal cycle

39
Q

what does peptide YY do?

A

Reduces appetite

Inhibits NPY release

40
Q

Comorbidities associated with obesity

A

Cardiovascular - stroke/ MI/ hypertension etc
Osteoarthritis/ gout
Sleep apnoea
Depression

Gastro Yr 2 (7 decks)

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