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2.8 BRS Gastroenterology > Upper GI > Flashcards

Upper GI Flashcards

1
Q

What are the components of the GI system?

A
  1. Salivary glands
    • parotid, sublingual, sub-mandibular
  2. Oesophagus
  3. Stomach
  4. Small bowel
    • duodenum, jejenum, ileum
  5. Liver and gall bladder
  6. Large bowel
    • appendix, ascending, transverse, descending,
      sigmoid colon
  7. Rectum
  8. Anus
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2
Q

What are the 4 layers of the gut wall?

A
  1. Mucosa —> innermost
    • epithelium, lamina propria (connective),
      muscularis mucosae
  2. Sub-mucosa
    • connective tissue
    • meissners plexus
    • submucosal glands
  3. Muscularis
    • longitudinal, circular (+oblique in stomach) muscle
    • myenteric plexus
  4. Serosa/Adventitia —> outermost
    • connective tissue (+epithelium)
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3
Q

What is the arrangement of teeth in the oral cavity?

A

32
- 8 incisors
- 4 canines
- 8 premolars
- 12 molars

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4
Q

Which muscle is responsible for biting?

A

Masseter —> largest jaw muscle

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5
Q

What are the 3 salivary glands?

A
  1. Parotid —> down from ear
  2. Sublingual —> under tongue
  3. Submandibular —> furthest down
    - aqueous —> soften food
    - enzymes —> salivary amylase
    —> lingual lipase
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6
Q

What are the 2 sets of muscles of the tongue?

A
  1. Intrinsic - only in tongue
    —> alter shape
  2. Extrinisic - attach to other structure
    —> move position of tongue
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7
Q

What is the structure of the oesophagus?

A
  • 25cm —> C5/6 to T10/11
  • in posterior mediastinum
  • start —> upper oesophageal sphincter (under
    cricopharyngeus muscle)
  • end —> cardia of stomach
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8
Q

What is the 15-25-40 rule?

A

Endoscopy —> marks constrictions:

  • 15 cm —> cricopharyngeal constriction
    - oesophagus starts
    - striated muscle (voluntary control)
  • 25 cm —> aortic and bronchial constriction
  • 40cm —> diaphragmatic and sphincter constriction
    - oesophagus ends (Z-line)
    - smooth muscle (involuntary control)
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9
Q

What is the function of the oesophagus?

A

Move food from pharynx to stomach
- Epithelium - non-keratinised, stratified, squamous
- damaged by extreme temps/textures
- lubricated by mucus
- Muscle - peristalsis
- upper —> striated
- closed at rest
lower —> mainly smooth
- vagus —> myenteric plexus

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10
Q

What are the 4 stages of swallowing?

A

Stage 0: Oral phase
- mouth forms bolus
- oesophageal sphincters closed

Stage 1: Pharyngeal phase
- bolus from pharynx to oesophagus
- oesophageal sphincters open

Stage 2: Upper oesophageal phase
- superior circular rings contract
inferior circular rings dilate
longitudinal muscle sequentially contracts
- upper sphincter closes

Stage 3: Lower oesophageal phase
- bolus to stomach
- lower sphincter closes

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11
Q

What is the gastro-oesophageal Z line?

A

Visible junction between oesophageal and gastric mucosa
- epithelial transition: stratified squamous —> simple
columnar (stomach acid protection)

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12
Q

What are the 3 functions of the stomach?

A
  1. Break down food
  2. Release food to duodenum steadily
  3. Kill parasites/bacteria
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13
Q

What is the structure of the stomach?

A
  1. Cardia —> joins to oesophagus
  2. Fundus —> top bend
  3. Body
  4. Pyloric —> bottom (antrum and canal)
    - rugae —> allow for expansion
    —> crypts for glands
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14
Q

Which 4 chemicals are secreted by the stomach?

A
  1. Mucus —> gel coat to protect tissue (+ rapid
    epithelial turnover)
    —> trap HCO3-
  2. HCl —> kill microorganisms
    - 2L/day
    - 150mM H+ conc
    - lumen pH 1-2 (epithelial surface 6-7)
  3. Pepsinogen —> denatures proteins
  4. Gastrin —> stimulates HCl production
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15
Q

What are the 5 secretory cells of the stomach?

A
  1. Chief —> pepsinogen
  2. Parietal —> HCl
  3. Mucus neck —> mucus
  4. Surface mucus —> mucus (traps HCO3-)
  5. Enteroendocrine —> gastrin
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16
Q

What is secreted from where in the stomach? (3)

A
  1. Cardia and pyloric —> mucus
  2. Body and fundus —> mucus
    —> HCl
    —> pepsinogen
  3. Antrum —> gastrin
17
Q

What is the function of gastric chief cells and how are they adapted?

A

Secrete pepsinogen (HCl cleaves to pepsin)
- inc RER
- inc golgi
- inc apical secretion granules

18
Q

What is the function of gastric parietal cells and how are they adapted?

A

Produce HCl
- inc mitochondria —> for H+/K+ ATPase
- internal canaliculi —> secretory
- project into canaliculi
- cytoplasmic tubulovesicles —> H+/K+ ATPase
- fuse with membrane

19
Q

How is stomach acid produced?

A
  1. CO2 diffuse from blood into parietal cell
  2. H2O into parietal cell via aquaporin
  3. CO2 + H2O —> H2CO3 using carbonic anhydrase
  4. H2CO3 —> H+ + HCO3
  5. H+ into lumen via H+/K+ ATPase
  6. HCO3- to blood via HCO3-/Cl- antiport —> Cl- in
  7. Cl- into lumen via fac diff
  8. H+ + Cl- —> HCl in lumen
20
Q

What are the 3 stimulants of HCl production?

A
  1. ECL cells produce histamine —> binds H2 receptor
  2. G cells produce gastrin —> binds to gastrin receptor
  3. Vagus nerve releases ACh —> bind to muscarinic
    receptor
21
Q

Which drugs inhibit stomach acid production and how? (3)

A
  1. Pantoprazole —> inhibits H+/K+ ATPase
    - PPI (proton pump inhibitor)
  2. Omeprazole —> inhibits H+/K+ ATPase
    - PPI (proton pump inhibitor)
  3. Ranitidine —> inhibits H2 receptor
22
Q

What is the function of gastrin?

A

Stimulates HCl production
- binds to parietal cell receptors
- stimulates histamine release from chromaffin cells
- secreted from pyloric antrum
- secretion stimulated by stomach distension, small
peptides and amino acids, vagus nerve

23
Q

What are the 3 phases of gastric secretion?

A
  1. Cephalic phase:
    • thought/sight —> cerebral cortex —>
      hypothalamus + medulla oblongata —> vagus
      nerve —> stomach secretions
    • taste/smell —> hypothalamus + medulla
      oblongata —> vagus nerve —> stomach secretions
  2. Gastric phase:
    • food in stomach —> distension —> stretch
      receptors —> medulla —> vagus nerve —>
      stomach
    • food chemicals/pH change —> chemoreceptors
      —> gastrin to blood
  3. Intestinal phase:
    • stomach emptying —> low pH in duodenum —>
      gastrin to blood
      *************

2.8 BRS Gastroenterology (13 decks)

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