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Physiology 2 > Exam 4: Gastric Secretion > Flashcards

Exam 4: Gastric Secretion Flashcards

1
Q

What are the 3 muscle layers of the stomach?

A

Outer longitudinal layer
Middle circular layer
Inner oblique layer

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2
Q

What is receptive relaxation?

A

When distention of the lower esophagus relaxes the LES and also orad stomach

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3
Q

Other than receptive relaxation, what else relaxes the LES?

A
  • Vasovagal reflex (afferent and efferents carried by vagus)

- VIP induced relaxation, released by vagus

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4
Q

What are gastric pits also known as and where in the stomach are they found?

A

Aka oxyntic glands

In the body of the stomach

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5
Q

Where in the stomach are pyloric glands found? What kind of cells do they contain?

A

Found in the antrum

Contain G cells and mucous neck cells

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6
Q

Where are chief cells found and what do they secrete?

A

Body of stomach

Pepsinogen

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7
Q

Where are parietal cells found and what do the secrete?

A

Body of stomach

HCL and intrinsic factor

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8
Q

Who do G cells secrete?

A

Gastrin

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9
Q

What do mucus cells secrete?

A

Mucus and pepsinogen

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10
Q

What are the 4 major components of gastric juice?

A

HCL, pepsinogen, mucus, and intrinsic factor

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11
Q

What does HCL in the stomach do?

A

Reduces the pH, activates pepsin, aids in protein digestion, and kills bacteria

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12
Q

What does pepsinogen do in the stomach?

A

Digests proteins

**pepsinogen is inactive, pepsin is active

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13
Q

What does mucus do in the stomach?

A

Protects the gastric mucosa from the corrosive actions of HCl

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14
Q

What does intrinsic factor do in the stomach?

A

Necessary for absorption of Vitamin B12 in the ileum

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15
Q

In the formation of HCl, what enzyme catalyzes the formation of H and HCO3?

A

Carbonic anhydrase

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16
Q

Where does HCl formation take place?

A

Gastric parietal cells

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17
Q

In HCL formation, after H is made via carbonic anhydrase, H is moved into the lumen in exchange for ** via **.
This is blocked by what drug?

A

K+
ATPase
Omeprazole

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18
Q

How does Cl get into the gastric parietal cells, so it can ultimately move across the apical membrane and form HCl?

A

Cl is exchanged for HCO3 on the basolateral membrane

19
Q

What is the function of gastrin?

A
  • stimulate acid and pepsinogen secretion
  • stimulate growth of gastric and intestinal mucosa
  • stimulate natural and intestinal motility
20
Q

Gastrin is released from G cells of the antrum when stimulated by what 3 things?

A
  • small peptides and amino acids in the stomach
  • distention of stomach
  • vagal stimulation
21
Q

What inhibits gastrin release?

A

Low ph (<3), somatostatin, and PGE2

22
Q

What are the 3 things that stimulate HCl release?

A

1) Gastrin stimulates partial cells via CCKb receptor
2) Gastrin stimulates ECL cells which release histamine, which bind to an H2 receptor on parietal cells
3) ACh

23
Q

What is the treatment of H. Pylori?

A

Antibiotics (clarithromycin or amoxicillin)

24
Q

What kind of drugs are Cimetidine and Ranitidine?

A

H2 blockers

25
Q

What kind of drugs are omeprazole and lansoprazole?

A

PPIs

26
Q

What causes peptic ulcer disease?

A
  • Excess acid secretion and/or damage to mucosal barrier (acid destroys mucosal cells and liberates histamine and histamine stimulates acid secretion
  • NSAIDS, inhibit COX and decrease PGs
  • H. Pylori infection
27
Q

What causes vomiting to occur?

A
  • The diaphragm lowers to the inspiratory position and the glottis closes
  • abdominal wall muscles contract increasing intra-abdominal pressure
  • stomach, esophagus, and LES relax and stomach gets squeezed between diaphragm and viscera
  • UES relaxes and vomit is projected into mouth
28
Q

How do ECL cells play a role in HCl secretion?

A

Gastrin stimulates ECL cells, which release histamin, which binds to H2 receptors on the parietal cells

29
Q

How does Atropine block HCl secretion?

A

It blocks M3 receptors

-when the vagus nerve releases ACh, atropine blocks the receptor that ACh is supposed to bind to

30
Q

How is HCl secretion controlled in the cephalexin phase?

A
  • PNS via the vagus directly stimulates parietal cells and also stimulates G cells to release gastrin
  • Gastrin conveyed by circulation, stimulates parietal cells
31
Q

What do the PNS nerves release in the cephalic phase that stimulate G cells to release gastrin?

A

Gastrin releasing peptide (GRP)

32
Q

What stimulates HCl release in the gastric phase?

A
  • release of amino acids and small peptides from parietal cells
  • distention of the stomach by local and vagovagal reflex arcs
  • histamine via H2 receptors
  • Alcohol and caffeine
33
Q

Is more HCL release in the gastric or cephalic phase?

A

Gastric

34
Q

What is pepsinogen released from?

A

Chief cells

35
Q

What converts inactive pepsinogen to its active form pepsin?

A

Acid, optimum pH is 1.5-2 and is denatured at 7

36
Q

What is the function of pepsin?

A

Cleave proteins to peptides at aromatic links

-digests 10-20% protein in the typical meal

37
Q

What stimulates the release of pepsinogen in the cephalic phase?

A

Vagus nerve

38
Q

What stimulates the release of pepsinogen in the gastric phase?

A

Luminal HCl locally stimulates release

Gastrin and secretin stimulate release

39
Q

What cells secrete gastric mucus?

A

Neck cells and surface epithelium

40
Q

Is gastric mucus acidic or alkalotic?

A

Alkaline- possess high bicarb level

41
Q

What stimulates mucus secretion?

A

PNS (Vagus), gastric distention, and PGs stimulate mucus and bicarb secretion

42
Q

What increases gastric mixing and emptying?

A

PNS stimulation, gastric distention, gastrin, and motilin

43
Q

What decreases gastric mixing and emptying?

A

-SNS stimulation, secretin, CCK, GIP, H+, digestion products of fats and proteins in the duodenum, and duodenal distention

Physiology 2 (13 decks)

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