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3 Gastrointestinal System > 7 Functions of the Stomach > Flashcards

7 Functions of the Stomach Flashcards

1
Q

What are the 2 families of hormones that have roles in the GI tract?

A
  • Gastrin family
  • Secretin family
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2
Q

What structural component of the stomach gives it its ability to distend?

A

Rugae (temporary folds) in the mucosa of the stomach

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3
Q

How many layers of muscle does the stomach have?

A

3 layers

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4
Q

What does the stomach do to help with protein digestion? (2)

A
  1. Unravel proteins- larger surface area
  2. Activates proteases
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5
Q

Name the cells that are responsible for acid production in the stomach. What are they stimulated by?

A

Parietal cells

Stimulated by gastrin, histamine, Ach (acting through CCK, H2, Mcr receptors on parietal cell)

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6
Q

What 2 factors will increase acid production from parietal cells?

A
  • Amino acids/peptides detected in stomach lumen
  • When stomach= distended
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7
Q

What 2 factors cause a reduction in stomach acid production?

A
  • When stomach distension reduces
  • Low pH detected in stomach
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8
Q

What are the 3 phases of digestion?

A
  1. Cephalic
  2. Gastric
  3. Intestinal
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9
Q

In simple terms, how does the stomach defend itself from its acidic environment?

A

Produces thick layer of alkaline mucus

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10
Q

What roles do the enteroendocrine and enterochromaffin cells have in the gut?

A

Enteroendocrine

  • Secrete hormones
  • (genrally identified by letters G, S, D)

Enterochromaffin

  • Secrete histamine
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11
Q

What veins drain the liver?

A

Hepatic veins drains liver

Portal vein DOESN’T drain liver

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12
Q

Give an example of neurocrine control of the stomach .

A

Gastrin releasing peptide

GRP released from post ganglionic fibres of vagus nerve

Increases release of Gastrin from G cells

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13
Q

Two hormones in the gastrin family are Gastrin and CCK (cholecystokinin). Where are these hormones released from and what are their functions?

A
  • Gastrin
    • Released: G cells in antrum of stomach
      • Increases gastric acid secretion
  • CCK (Cholecytokinin)
    • Released: I cells in duodenum and jejunum
      • Increases pancreatic and gallbladder secretions
        • Stimulated by fat and protein
        • Gall bladdder contracts
        • Pancreas stimulated

(Gastrin and CCK very similar- some of the receptors are interchangeable)

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14
Q

Two hormones in the secretin family and Secretin and Gastric Inhibitory Polypeptide. Where are each of these hormones secreted from and what are their functions?

A
  • Secretin
    • S cells in duodenum
    • Stimulated by H+ and fatty acids
      • Increase HCO3 from pancreas/gallbladder
      • Decreases gastric acid secretion
  • Gastric Inhibitory Polypeptide
    • Cells in duodenum and jejenum
    • Stimulated by sugars, amino acids and fatty acids
      • Increase insulin
      • Decreased gastric acid secretion
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15
Q

Locate the stomach on this image.

A
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16
Q

Fill in the missing labels:

A
17
Q

Describe the transition of epithelial cell types from the lower oesophagus to the stomach.

A

Abrupt transition

Stratified squamous–> columnar

18
Q

Fill in the missing gaps 1-5:

A
19
Q

Fill in the missing labels:

A
20
Q

Different cell types are distributed differently in the stomach. What substances are primarily secreted in the:

Cardia

Fundus/body

Pylorus

A
21
Q

Fill in the missing labels on the coeliac trunk: 1-11

(Watch video again: https://youtu.be/5ZWooxbJCEg)

A
22
Q

If a patient has an ulcer in the first part of the duodenum which artery could it perforate into? What will happen to the patient?

A

Gastroduodenal artery

Patient will vomit up blood/ have blood in peritoneal cavity

23
Q

Name the vein that drains evrything from the gut

A

Portal vein

24
Q

Relaxation of the stomach is vagally mediated and the rugae facilitate the distension of the stomach. Why is the stomachs ability to relax so important?

A

We consume food faster than we can digest it

  • Need to store food
  • Allow food to enter stomach without raising intra-gastric pressure
  • Prevent reflux of stomach contents
25
Q

Stomach acid unravels ingested proteins and also activates proteases eg. pepsinogen to pepsin. Why is this necessary?

A

Unravel proteins to help with digestion

So we don’t break our own cells down

26
Q

Name 3 substances/molecules that stimulate parietal (oxyntic) cells (to release HCl).

A
  1. Gastrin
  2. Histamine
  3. Ach
27
Q

There are 3 ‘ON’ buttons that cause parietal (oxyntic) cells to release HCl. How do eahc of these work? (Ach, Histamine, Gastrin)

A
  1. Gastrin
    1. Stimulate CCK (cholecystokinin) receptors on parietal cell
    2. Acid released
  2. Histamine (like amplifier)
    1. Modulates input from gastrin
  3. Ach
    1. Vagus nerve stimulates muscarinic receptor using ACh
28
Q

Where is gastrin secreted from and how is it controlled?

A

Secreted from:

  • G cells in antrum of stomach

Stimulated by:

  • Peptides and amino acids in stomach lumen
  • Vagal stimulation
    • Acetylcholine
    • Gastrin releasing peptide
29
Q

At a molecular level- describe how the parietal cell produces acid.

A
  • H+/K+ ATPase
    • Pumps hydrogen out into stomach lumen
  • Water split inside cell

Venous blood leaving blood made slightly more alkaline- bicarbonate used later on in GI tract

30
Q

Need to be able to explain stomach secretions. Use these diagrams- talk it through.

A
31
Q

What are the 3 phases of digestion and what happens during each phase?

A
  1. Cephalic (30% HCl Production)
    1. Parasympathetic stimuli
      1. Vagus nerve stimulates parietal cells and G cells (before food swallowed- anticipating food)
    2. Increased gastric motility
  2. Gastric (60% HCl production)
    1. Food distends stomach
        • stimulates Vagus
          1. Stimulates parietal cells and G cells
    2. Amino acids and peptides stimulate G cells
    3. Food acts as buffer- removes inhibition on gastrin secretion
    4. Enteric nervous system causes strong smooth muscle contractions
  3. Intestinal (10% HCl production)​
    1. ​Chyme initally stimulates gastrin secretion
    2. THEN inhibition of G cells
      1. enterogastric reflex-activated by presence of lipids
        1. reduce vagal stimulation
32
Q

How does the stomach protect itself from its own secretions?

A
33
Q

What is the effect of NSAIDs on prostaglandin release?

A

Decrease prostaglandin release

34
Q

Give examples of sunstances that can breach the stomach defences

A
35
Q

Which arteries supply the greater and lesser curves of the stomach?

A
  • Lesser curve
    • Left and right gastric arteries
  • Greater curve
    • Left and right gastroepiploic arteries

3 Gastrointestinal System (19 decks)

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