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Histology CAM202 > 2. Oesophagus and Stomach > Flashcards

2. Oesophagus and Stomach Flashcards

1
Q

WHAT are the 4 Layers of the GIT

A
  1. Tunica Mucsa
  2. Tunica Submucosa
  3. Tunica Muscularis
  4. Tunica Serosa
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2
Q

What is in the first layer?

A

TUNICA MUCOSA

  • Epithelium (simple columnar except for oral cavity/oropharynx, laryngopharynx, oesophagus, anal canal - which are all stratified squamous epithelium)
  • LAMINA PROPRIA
  • MUSCULARIS MUCOSA
  • most of the structural changes seen as you pass along the alimentary tract involve the tunica mucosa. There are changes in the epithelium and associated glands. The functions of the GIT include secretion, absorption, excretion, contraction, peristalsis, mixing, protection, lubrication etc. The structure reflects the function
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3
Q

What is the second layer and whats in it

A

TUNICA SUBMUCOSA

- Dense irregular Connective tissue- may find glands and MALT also

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4
Q

What is the third layer and whats in it?

A

TUNICA MUSCULARIS

  • Inner circular
  • Outer Longitudinal
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5
Q

What is the fourth layer and whats in it

A

TUNICA SEROSA or ADVENTITIA
- Simple squamous epithelium (mesothelim) and/or Connective tissue

simple squamous epith provides low friction surface.

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6
Q

Oesophagus

A

Joins the pharynx to the stomach.

Function: transport food to stomach.

What sort of mucosa?
- a protective epithelium: STRATIFIED SQUAMOUS NON KERATINISED EPITHELIUM. Lubrication provided by saliva from the oral cavity. Muscles for movement.

Has a collapsed lumen.
Tunica submucosa: glandds
Tunica Muscularis: can be smooth and/or skeletal muscle.
Tunica ADVENTITIA predominantly- why? Because oesophagus doesnt move hence adventitia.

In the oesophagus-= skeletal muscle has more eosinophilic bands than smooth muscle.

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7
Q

Where in the oesophagus do we find skeletal muscle and where do we find smooth muscle?

A

Upper 1/3 = skeltal

Lower 2/3 = mixed (mainly smooth)

Muscularis mucosa is where you find most of the muscle

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8
Q

Explain the cario-oesophageal junction

A

The junction between the oeosphagus and the stomach displays an abrupt change in the epithelium of the mucosa. There is a change from stratified squamous epithelium to SIMPLE COLUMNAR. Also the epithelium of the stomach mucosa quickly arranges itself into gastric glands. These are mucosal glands.

CARDIAC REGION of Stomach: Gastric pits; gastric glands; lymphatic nodules

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9
Q

What are the 3 main histological regions of the stomach?

A
  1. Cardiac
    2- Fundus + Body
    3- Pyloric Region
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10
Q

Muscularis Layer is UNIQUE in the stomach- how so?

A
  • -> Innermost oblique layer- which is incoplete on the sides
  • -> middle circular layer
  • -> Outer longitudinal layer
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11
Q

Clinical Consideration- Gastric Reflux

A

Backward glow of gastric contents up the oesophagus even as high as the larynx and pharynx (laryngopharyngeal reflux ; LPR)

GER can lead to heart burn, mucosal ulceration, narrowing of the oesohagus, Barretts metaplasia, and eventually oesophageal cancer

LPR can lead to vocal changes (Clinton), narrowing of the larynx, laryngospasm or even head and neck cancers.

A whole range of factors have been suggested to contribute to reflux including transient relaxations of the LOS, hypotension of the LES, and poor oesophageal motility (and neutralisation by saliva)

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12
Q

Explain the histology of the stomach (general)

A

The stomach is lined by a simple columnar epithelium. there are no goblet cells.

All of the cells of the epithelium are secreting ALKALINE MUCOUS

There are depressions on the surface called GASTRIC PITS. These are lined by the same epithelium and cells as the surface epithelium- pits vary in depth depending on location in the stomach.

Several GASTRIC GLANDS open into the base of each pit. the glands form as down growths of the epithelium. The glands secrete different substances depending on location

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13
Q

Cardiac Region of the stomach

A

The cardiac region is so small- 1-2cm a tthe entrance of the oesopahgus.

Gastric pits are 3-40% of the entire mucosa. Scattered with SIGNIFICANT amounts of lamina propria (CT) present between pits and glands.

Glands are SPARSE, COILED, MUCOUS SECRETING (protection of oesophagus against reflux)

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14
Q

Pyloric Region of the stomach

A

Gastric pits are quite DEEEP, 50% of mucosa depth!!!!!

Glands are NUMEROUS,
COILED TUBULAR
MUCOUS SECRETING - alkaline, protection of duodenum against acid.

Significant amounts of lamina propria are present between the pits and glands

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15
Q

BODY or FUNDIC region of the stomach

A

MAJORITY OF THE STOMACH

Many GASTRIC PITS tightly packed together!!

Pits are SHALLOW- 10-15% of the mucosa depth

2 r 3 gastric glands opening into the base of each gastric pit- Lots of glands

Lamina Propria difficult to see.

Glandular area often appearsa as TWO LAYERS

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16
Q

Cell types in the body of the stomach

A

SURFACE of the STOMACH:
and the pits are covered by SIMPLE COLUMNAR epithelium where all the cells are described as SURFACE MUCOUS SECRETING CELLS- these are not goblet cells.

The GLANDS CONTAIN:

  1. Mucous Neck Cells
  2. Parietal Cells
  3. Chief cells
  4. Enteroendocrine cell

*The parietal cells are mostly in the upper part of the gland whereas the peptic cells are in the base of the gland.

Base => NECK => ISTHMUS => PIT

Parietal cells = eosinophilic
Chief Cells = Basophillic , responsible for banding when stained with H& E

17
Q

Explain the structure of the Parietal Cell- and what does it secrete?

  • also called oxyntic
A

Found mainly in upper areas of the glands “fried egg”

At high power light micrograph of the upper region of a fundic gland showing a group of parietal cells.

Note the round centrally placed nucleus and the abdundant eosinophilic cytoplasm.

Canaliculi in paler areas.

SECRETE: HCL and INTRINSIC FACTOR

Eosinophilic staining cells with mitochondria and smooth membrane tubulovesicular system.

Canaliculi obvious when secreting

18
Q

CHIEF or Zymogenic Cells

A

In the BASE of the gastric gland

PROTEIN SECRETING cells- PEPSINOGENS are secreted and converted to active PEPSIN by HCL within the lumen of the stomach.
have ‘zymogenic granules)

Basophilic staining particularly base of cell (rER)

Basal nucleus

Stimulated to secrete by parasympathetic (Vagus) nerve innervation and the secretion of gastrin and histamine from enteroendocrine cells of the stomach

19
Q

Enteroendocrine Cells

A

Cant identify with normal H&E staining.

An electonmicrograph of an enteroendocrine cell:
Note:
1. the Microvilli on the luminal surface to sample the luminal contents.
2. Secretory vesicles (endocrine) adjacent to the basement membrane.

Enteroendocrine cells are found throughout the GIT but particularly in the stomach and SI

Histology CAM202 (4 decks)

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