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An Sc 311 Midterm 1 > Lecture 4 - Regulation > Flashcards

Lecture 4 - Regulation Flashcards

1
Q

What kind of receptors does the gut sense with

A

Chemoreceptors
Mechanoreceptors (stretch)

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2
Q

Chemoreceptors sense a change in…

A

nutrient concentration
nutrient degradation products
osmotic pressure
pH

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3
Q

What does gastrin induce? When?

A

Acid secretion
pH too neutral

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4
Q

Wall stretch activates

A

acetylcholine

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5
Q

What does low pH in the bloodstream activate

A

Release of secretin, goes into bloodstream then to pancreas, activates bicarbonate release (increase pH)

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6
Q

What cells release bicarbonate

A

Duct cells

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7
Q

What cells lower the pH of the stomach

A

Parietal

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8
Q

What are endocrine hormones? Where do they bind?

A

Hormones released into general circulation
Specificity to property of target tissue, binds specific receptors

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9
Q

Examples of endocrine hormones

A

gastrin, secretin, cholecystokinin, motilin

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10
Q

What are paracrine hormones

A

Released from endocrine cells, diffuse through extracellular space to neighbouring target cell

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11
Q

What are autocrine and neurocrine hormones

A

Autocrine = released substance regulates cell’s own function
Neurocrine = sensory cells secrete neurotransmitter

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12
Q

What activates
1. gastrin
2. GLP
3. CCK
4. secretin

A
  1. peptides, AA
  2. glucose, AA, FA
  3. FA, AA
  4. acid
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13
Q

Roles of CCK (4)

A

Gallbladder = contraction (secrete bile)
Pancreas = acinar secretion (pancreatic enzymes)
Stomach = reduced emptying
Sphincter of oddi = relaxation (opening)

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14
Q

Gastrin stimulates… Secretin stimulates…

A

Gastric secretion and mucosal growth

Pancreatic HCO3 secretion (increases pH)

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15
Q

Three steps of endocrine system and their roles

A
  1. signaling cells (organ): physiological stimulus, hormone synthesis, secretion
  2. transport by the circulatory system
  3. target cells (organ): receptor, biological effects
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16
Q

If the endocrine hormone is hydrophilic, it will also require…

A

Storage for hormone in signaling cell, second messengers in target cell

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17
Q

Can hydrophobic hormones cross the membrane?

A

Yes, hydrophilic hormones cannot (require secondary messenger)

18
Q

Memorize slides 11, 13**

A

Hydrophobic/hydrophilic hormone pathways

19
Q

Difference btw hydrophobic and hydrophilic hormones in signaling and target cells

A

Signaling cells = hydrophobic are synthesized on demand (no storage) and diffused, hydrophilic cells are exocytosed (cannot cross membrane)

Target cells = hydrophilic require transmembrane receptors (cannot enter) and second messengers and are rapid. Hydrophobic diffuse, bind inside cell, alter mRNA transcription, slower

20
Q

How are hydrophobic hormones transported through the blood

A

Carrier proteins (most have specific)

21
Q

What acts as a non-specific carrier for hydrophobic hormones

A

Serum albumin

22
Q

What does glucagon-like peptide 1 respond to? Enhance? Inhibit? What degrades it? Where is it produced?

A

Responds to nutrients and short chain f.a.
Enhances insulin secretion
Inhibits gastric emptying
Degraded by DPP IV
Produced in L-cells in intestine and colon

23
Q

Where is ghrelin produced? When is it secreted? Detects…

A

Produced by cells lining the fundus of the stomach
Secreted when the stomach is empty
Detects hunger

24
Q

Ghrelin acts on the hypothalamus to…

A

increase hunger, gastric secretions, GIT motility

25
Q

What are the GIT factors that regulate satiety

A
  1. Stretch (via vagal afferent nerves)
  2. CCK (via vagal afferent nerves)
  3. Nutrient receptors in liver (via vagal afferent nerves)
  4. Peptide YY (acts on vagal afferents and hypothalamus)
26
Q

Non-GIT factors regulating satiety

A

Adipose (leptin acts on hypothalamus)
Pancreas (insulin)

27
Q

Where is leptin produced?

A

Adipocytes

28
Q

Leptin acts on the hypothalamus to…

A

Reduce hunger (binds leptin receptor)

29
Q

How does leptin affect fat reserves

A

Inhibits feeding
Inhibits fat synthesis

30
Q

Slides 32/33 **

A

Regulation of leptin/ghrelin

31
Q

Deletion of what gene is related to obesity in labs

A

POMC gene

32
Q

Slide 36**

A

Review leptin, ghrelin, PYY, insulin

33
Q

Do fat animals have leptin?

A

Yes, lots, but their cells have become resistant to it

34
Q

Slide 38

A

Leptin responsiveness vs resistance

35
Q

What is the epigenetic effect

A

Exposure to excessive nutrients in utero or in early postnatal period = hyperphagia
Utero environment affects POMC expression

36
Q

What is an additional food intake factor to consider

A

Hedonic regulation of food intake (reward/pleasure seeking areas of the brain control hypothalamic area)

37
Q

Is acetylcholine a peptide

A

No

38
Q

Which of gastrin, somatostatin, cholecystokinin, GLP and secretin are peptides?

A

All

39
Q

What is an anorexic vs orexic hormone

A

Anorexic = stop eating (leptin)
Orexic = hungry (ghrelin)

40
Q

What neurons drive anorexic signals? Orexic?

A

Anorexic = POMC/CART
Orexic = ArRP/NPY

An Sc 311 Midterm 1 (8 decks)

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