Food Intake Regulation Flashcards

1
Q

Where are the neuronal control centers for feeding and satiety?

A

Hypothalamus

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2
Q

What are the main neuronal control center nuclei in the hypothalamus that control feeding and satiety behaviors?

A

Arcuate nucleus

Paraventricular nucleus

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3
Q

In general, neurons from ______ are sent to synapse to neurons in _______

A

Arcuate nucleus neurons are sent to synapse to neurons in the paraventricular nucleus

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4
Q

What pathway tries to decrease food intake and increase energy expenditure?

A

Anorexigenic pathway

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5
Q

What pathway tries to increase food intake and decrease energy expenditure?

A

Orexigenic pathway

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6
Q

For the anorexigenic pathway, what type of neurons are used in the arcuate nucleus?

A

Pro-opiomelanocortin (POMC) neurons

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7
Q

What do POMC neurons release at their synapse?

A

Alpha-MSH

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8
Q

POMC neurons release Alpha-MSH to what receptor?

A

MCR-4

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9
Q

For the orexigenic pathway, what type of neurons are used in the arcuate nucleus?

A

AGRP/NPY neurons

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10
Q

What do AGRP/NPY neurons release at their synapse?

A
Neuropeptide Y (NPY) OR
AGRP
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11
Q

Neuropeptide Y (NPY) binds to what receptor?

A

Y1R

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12
Q

AGRP binds to what receptor?

A

It is an ANTAGONIST for MCR-4

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13
Q

The anorexigenic pathway and the orexigenic pathway try to antagonize each other. Explain the ways they do so.

A
  1. POMC neurons can release Alpha-MSH to NPY/AGRP neurons
  2. NPY/AGRP neurons can release NPY to POMC neurons
  3. AGRP can try to bind the MCR-4 receptor at the paraventricular neurons so that POMC neurons cannot have Alpha-MSH bind them
  4. Stimuli that activate one pathway will also try and inhibit the other pathway
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14
Q

What kind of stimuli will activate the Anorexigenic pathway?

A

Leptin
Insulin
CCK

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15
Q

What kind of stimuli will activate the Orexigenic pathway?

A

Ghrelin

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16
Q

If the Anorexigenic pathway is activated, what is the end result?

A

Decreased food intake

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17
Q

If the orexigenic pathway is activated, what is the end result?

A

Increased food intake

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18
Q

Describe the Anorexigenic pathway

A
  1. Leptin, Insulin, CCK activate POMC neuron in the arcuate nucleus
  2. POMC neuron travels to the paraventricular nucleus
  3. POMC releases Alpha-MSH
  4. Alpha-MSH binds to MCR-4 receptor
  5. Paraventricular neuron signals for decreased food intake
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19
Q

Describe the Orexigenic pathway

A
  1. Ghrelin activates NPY/AGRP neuron in the arcuate nucleus
  2. NPY/AGRP neuron travels to the paraventricular nucleus
  3. NPY/AGRP releases NPY (neuropeptide Y)
  4. NPY binds to Y1R receptor
  5. Paraventricular neuron signals for increased food intake
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20
Q

What are 4 GENETIC causes of obesity?

A
  1. Prader-willi syndrome
  2. Leptin deficiency
  3. POMC neuron deficiency
  4. MCR-4 mutation
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21
Q

Prader-willi syndrome is caused from?

A

Partial deletion of chromosome 15 OR

Loss of paternally expressed genes

22
Q

Mutations in ____ pathway may cause obesity

A

Anorexigenic

23
Q

What components of the Anorexigenic pathway can have mutations that lead to obesity?

A

POMC neuron and MCR-4 receptor

24
Q

The _____ nerve is also important in controlling feeding behavior and metabolism

A

Vagus nerve

25
Q

Where do the vagal afferents project?

A

Nucleus Tractus Solitarius

26
Q

Vagal signaling to the NTS is integrated with information received by the hypothalamus to?

A

Produce appropriate feeding behavior and metabolic responses

27
Q

_____ can also regulate food intake even in absence of higher center’s input

A

Hindbrain

28
Q

If vagal activity is BLOCKED, what happens?

A

Amount of material in the stomach NO longer influences meal size!

29
Q

What secretes Ghrelin and what does it bind to?

A

Stomach endocrine cells

GHSR

30
Q

Ghrelin stimulates release of _____

A

NPY

31
Q

What is the main hormone that initiates the feeding response?

A

Ghrelin

32
Q

Effects of Ghrelin

A

Increased appetite, GI motility and GI acid secretion

33
Q

What secretes Insulin and what does it bind to?

A

Beta cells in the pancreas

POMC AND NPY systems

34
Q

Insulin effects on the POMC and NPY systems

A

(+) POMC

(-) NPY

35
Q

Effects of insulin

A

Increased metabolism and decreased appetite

36
Q

With what disease were the insulin effects seen to be true?

A

Type 1 Diabetes

  • No insulin = increased appetite
  • normal insulin = decreased appetite
37
Q

What secretes CCK and what does it act on?

A

I cells in the duodenum

Acts on the Vagal-NTS-hypothalamic circuit

38
Q

Effects of CCK

A

Elicits satiety

Decreased Ghrelin and gastric emptying

39
Q

What secretes PYY and what does it bind to?

A

L cells in the ileum and colon

Y2R receptor in hypothalamus

40
Q

Effects of PYY

A

(-) NPY neurons

41
Q

What secretes Leptin and what does it bind to?

A

Adipose tissue

POMC and NPY systems

42
Q

Effects of Leptin

A

Decreased appetite and ghrelin

Increased metabolism

43
Q

Normally, obesity in humans is associated with what type of leptin levels?

A

HIGH = leptin resistance!

44
Q

_____ signals long term regulation of energy balance

A

Adipose

45
Q

______ modulate food intake on a meal - by - meal basis

A

Gut peptides

46
Q

What are 5 other hormones that DECREASE food intake?

A
GLP-1
Glucagon
Pancreatic Polypeptide
Amylin
Oxyntomodulin
47
Q

Anorexia Nervosa

A

Self-starvation and weight loss

- possibly due to polymorphisms in genes involved in eating attitudes and behaviors

48
Q

What may be a factor in diet restriction for anorexia nervosa?

A

Ghrelin resistance

49
Q

Levels of PYY are ______ with anorexia nervosa

A

Increased

50
Q

What other unrelated hormones can be decreased due to anorexia nervosa?

A

Leptin
TSH/T3
Testosteron/Estrogen

51
Q

What other hormones can be increased due to anorexia nervosa?

A

Ghrelin
PYY
Cortisol