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Allie GI/Renal > 3 - Gastric Motility and Satiety PPT > Flashcards

3 - Gastric Motility and Satiety PPT Flashcards

GI Tract, ROLL OUT!

1
Q

What are the three parts of the stomach?

A
  1. Fundus
  2. Body
  3. Antrum
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2
Q

Name the two regions of the stomach.

A

Orad and Caudad

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3
Q

What is the mucosa layer?

A

It is the innermost layer and it is modified: it contains various glands filled with different cells and it secretes components of gastric juice (JUNGLE JUICE)

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4
Q

The mucosa contains four different secretory cells, what are they?

A
  1. Parietal cells
  2. Chief cells
  3. Mucous cells
  4. G Cells
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5
Q

What are parietal cells?

A

Mucosa cells also known as oxyntic that secrete HCL and intrinsic factor

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6
Q

What is the special function of intrinsic factor?

A

It absorbs Vit. B12 (Cobalamin)

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7
Q

What are Chief cells?

A

Mucosa cells that secrete pepsinogen

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8
Q

What is pepsinogen?

A

An inactive enzyme that’s activated by HCL and helps break down protein

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9
Q

What factor of HCL tells pepsinogen to activate?

A

Its low pH

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10
Q

What are Mucous cells?

A

Mucosa cells that secrete (guess what) mucus, which protects the stomach lining from the acidic environment

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11
Q

What are G cells?

A

Mucosa cells that secretes Gastrin (hormone) into the blood

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12
Q

G cells secrete Gastrin. What does Gastrin do?

A

Increases secretions of HCL and pepsinogen and increases contractions of the stomach

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13
Q

What does the Submucosa layer of the stomach contain?

A

Contains the submucosal plexus (Meissner’s plexus) and blood vessels

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14
Q

What does the submucosal plexus (Meissner’s plexus) control?

A

It controls secretions and gastric blood flow

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15
Q

What is unique about the Muscularis Externa?

A

It is modified with three layers of its own that involuntarily contract to produce peristalsis!

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16
Q

What are the three layers of the stomach’s Muscularis Externa?

A
  1. Outer longitudinal
  2. Middle circular
  3. Inner oblique
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17
Q

Which layer of the stomach’s Muscularis Externa is unique to only the stomach?
Test Q

A

Inner oblique layer

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18
Q

What purpose does the inner oblique layer aid?

A

Helps provide more forceful contraction in the stomach

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19
Q

What is the outermost layer of the stomach?

A

The Serosa

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20
Q

What are the three components of gastric motility?

A
  1. Receptive relaxation
  2. Gastric contractions
  3. Gastric emptying
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21
Q

What occurs during the receptive relaxation component of gastric motility?

A
  • Relaxation of lower esophageal sphincter
  • Orad region of stomach receives B O L U S
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22
Q

Which cranial nerve is involved with receptive relaxation?

A

CN 10 (Vagus)

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23
Q

What occurs during the gastric contraction component of gastric motility?

A
  • BOLUS gets frickin’ obliterated
  • BOLUS remains are mixed with gastric secretions to initiate digestion
24
Q

What occurs during the gastric emptying component of gastric motility?

A

Chyme is propelled to the small intestine

25
Q

How is the gastric emptying rate determined?

A

It is HORMONALLY determined, which allows adequate time for the small intestine’s digestion and absorption

26
Q

What is important to remember as far as flow rate goes for gastric emptying?

A

Liquids move faster than solids!!

27
Q

Back to the receptive relaxation component- what duh hec is the Vagovagal reflex?

A

A reflex in which both afferent and efferent signals are carried by the Vagus nerve (CN X) from stomach to brain, then brain to stomach.

28
Q

Which region of the stomach produces strong contractions needed to πŸ…³πŸ…΄πŸ…²πŸ…ΈπŸ…ΌπŸ…°πŸ†ƒπŸ…΄ the BOLUS?

A

Caudad region!

29
Q

Where do contraction waves begin in the stomach body?

A

The mΜ²iΜ²dΜ²dΜ²lΜ²eΜ² stomach body

30
Q

Contraction waves steadily increase in strength as the BOLUS approaches the…

A

… pylorus.

31
Q

Periodically, these contractions in the middle stomach body will do what with the gastric contents?

A

They propel the gastric contents through the pylorus and into the duodenum.

32
Q

What is retropulsion of gastric contents?

A

When the gastric contents get propelled back into the stomach for further mixing.

33
Q

Why can’t all of the chyme be shot into the duodenum at once?
(This was asked in class)

A

The lining can’t handle the acidity all at once, it must be slowly and periodically put into the duodenum.

34
Q

What three factors 𝐒𝐧𝐜𝐫𝐞𝐚𝐬𝐞 the frequency of AP and force of contraction?

A
  1. Parasympathetic stimulation
  2. Gastrin
  3. Motilin

Parasympathetic: rest and digest. The body can focus entirely on processing the BOLUS!!!

35
Q

What three factors 𝐝𝐞𝐜𝐫𝐞𝐚𝐬𝐞 the frequency of AP and force of contraction?

A
  1. Sympathetic stimulation
  2. Secretin
  3. Gastric inhibitory peptide (GIP)

Sympathetic: fight or flight. Screw digesting the QT taquito you just ate, there’s a coked out homeless guy chasing you with a whip he fashioned out of his own hair!!!

36
Q

Just to refresh- where are the hormones Secretin and GIP secreted from?

A

Secretin: duodenal S cells
GIP: intestinal K cells

Idea: β€œSecretin Seeps (for S cell), GIP Kascades (for K cells)”

37
Q

How long does it take to empty the stomach of its contents?

A

3 hours

38
Q

Why on God’s green earth does it take so dadgum long to empty the stomach?

A

BECAUSE, the stomach acid must be properly neutralized and the adequate absorption of nutrients must occur.

39
Q

When we talk about factors that will increase gastric emptying time, we are essentially talking about factors that will…

A

… slow the gastric emptying process. Increasing the time it takes to empty will slow the overall process.

40
Q

What are two factors that increase the gastric emptying time?

A
  1. pH in the duodenum (presence of H+ ions)
  2. Increased fatty acids
41
Q

What does a higher concentration of H+ ions mean for gastric emptying time?

A

The contents are more acidic (lower pH) and this acidity is detected by H+ receptors. They activate interneurons in the myenteric plexus (Auerbach’s plexus), which tell the smooth muscle to slow gastric emptying. This gives the GI tract ample time to neutralize the acidity with ππ€ππ‚π‘π„π€π“πˆπ‚ π‡π‚πŸŽπŸ‘- (ππˆπ‚π€π‘ππŽππ€π“π„).

42
Q

What should we always think of when we see ππˆπ‚π€π‘ππŽππ€π“π„?

A

π˜½π˜Όπ™Žπ™„π˜Ύ

43
Q

A high-fat meal will slow gastric emptying time. What is secreted that increases gastric emptying time to allow for the complete digestion of the fats?

A

Cholecystokinin (CCK) (from duodenal 𝐼 cells)

44
Q

What part of the brain controls appetite and satiety?

A

The hypothalamus

45
Q

What are the three parts of the hypothalamus that regulate food intake?

A
  1. Ventromedial nuclei
  2. Lateral hypothalamic area
  3. Arcuate nucleus
46
Q

Which of these three parts controls your satiety (fullness)?

A

Ventromedial nuclei

47
Q

Which of these three parts controls your feeding (hangry)?

A

Lateral hypothalamic area

48
Q

Which of these three parts controls both sensations by circulating the two signals to reflect energy stores (am I actually hungry or do I just want to snack on something)?

A

Arcuate nucleus

49
Q

Okay expert, tell me what happens during a hunger sensation.

A

Well, acktchually,
1. Mechanoreceptors activate and slowly fire through the Vagus (CN X) towards the solitary nucleus
2. Solitary nucleus then stimulates the arcuate nucleus (do we feed or do we ignore)
3. Low blood glucose levels trigger G cells in the stomach lining to release Ghrelin (hunger hormone)
4. Ghrelin goes directly to the arcuate nucleus, stimulating the feeding center and inhibiting the satiety center
Duh.

50
Q

List in great detail all of the steps of satiety as seen on slide 7 of the PPT, no bulletpoints, minimum 4000 words.

A

Just kidding, we won’t do that. I’ll simplify it to the best of my ability. How about you take a sec to drink some water?

51
Q

What happens during satiety (simplified version)?

A
  1. Mechanoreceptors activate, send info via Vagus (CN X) that tells the arcuate nucleus to decrease feeding stimulation, increase satiety stimulation
  2. Breakdown of BOLUS by various chemical means triggers chemoreceptors
  3. Chemoreceptors send enteric signals to stimulate the release of various hormones by enteroendocrine cells
  4. 𝐼 cells release CCK after stimulation via presence of fats and proteins, which triggers gallbladder contraction and gut motility
  5. Ghrelin secretion inhibited, insulin secretion increased
  6. Leptin is released alongside insulin to tell you, β€œYou’re done dawg”
52
Q

Which hormones are considered short-term/acute satiety hormones?

A
  • CCK
  • Peptide YY
  • Peptide 1
  • Insulin
53
Q

Why is Leptin considered a long-term satiety hormone?

A

Its level in the blood remains stable throughout the day

54
Q

What produces Leptin?

A

Adipose cells

55
Q

What part of the brain does Leptin act upon to reduce hunger/increase satiety?

A

Hypothalamus

56
Q

Why is Leptin crucial to maintaining a healthy weight?

A

Because it helps prevent overeating and obesity by telling you when to quit- you’re full!

Allie GI/Renal (18 decks)

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