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Digestive MBChB 2 > Lecture 8; Salivary glands, oesophagus and stomach microanatomy > Flashcards

Lecture 8; Salivary glands, oesophagus and stomach microanatomy Flashcards

1
Q

What are the mucosal specialisations?

A

Stomach; gastric pits and glands
SI; Crypts of lieberhuhn and villi (small increase SA)

Transient folds; Rugae of stomach
Permanent folds; plicae circularis of SI

Lymphatic nodules

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2
Q

What are the tunics?

A
  1. Mucosa
    - Epithelium
    - lamina propria
    - Muscularis mucosae
  2. Submucosa
  3. Muscularis externa
  4. Adventitia or Serosa
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3
Q

Describe the mucosal function;

A

Epithelium;

  • Secretion (glands)
  • Mechanical protection (st. sq.)
  • Absorption

Lamina propria;

  • Support -> BV, lymph and nerve.
    - > Structural (collagen)

Muscularis mucosae;
- Movement of mucosae indp. of peristalsis i.e for secretions

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4
Q

What is the function of the submocosa?

A

Support like lamina propria

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5
Q

What is the function of the muscularis externa?

A

Co-ordinated contraction of inner circular and outer longitudinal layers (Smooth muscle) (some exceptions to the two layers).

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6
Q

Describe the adventitia and serosa;

A

Adventitia; Outermost connective tissue covering of any organ, vessel or other structure.

Serosa; a.k.a visceral peritoneum. Slippery outer covering for the gut tube; two layered, Outer mesothelium sitting on a bed of connective tissue. (Serous fluid)

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7
Q

What is ascites?

A
  • Accumulation of fluid from serosa lining (recycles fluid in peritoneum). leads to abdominal swelling, distortion of visceral organs.
  • Unusual conditions can lead to this; Liver disease, heart failure, electrolyte imbalance.
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8
Q

What is peritonitis?

A
  • Physical trauma, chemical irritation, bacterial invasion from surgery can cause peritonitis
  • Inflammation interferes with normal function.
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9
Q

What are the three major salivary glands?

A
  • Sublingual
  • Parotid
  • Submandibular
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10
Q

What are the fluids secreted by the three glands?

A

Sublingual -> Mixed, mainly mucous
Parotid -> Serous only
Submandibular -> Mixed serous and mucous

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11
Q

Describe the cells found in a serous acinar;

A
  • Zymogen granules near lumen
  • Large circular nuclei
  • Surrounded by myoepithelial cells
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12
Q

Describe the appearance of the mucous acinar;

A
  • Pushed squished peripheral nuclei

- No zymogen granules, but filled with many mucin granules.

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13
Q

Describe the ducts of the submandibular gland;

A
  • Intralobular ducts are striated peripherally as they are filled with mitochondria.
  • Intralobular lead to interlobular and submandibular ducts eventually.
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14
Q

Describe the composition of saliva;

A
  • Water

- CHO glycoproteins (Mucins)

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15
Q

What is the function of mucins in saliva?

A

Protection against

  • Bacterial adhesion and secretions
  • Vomit

Mucous filled with bi-carb which mediates protection.

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16
Q

What are some specific immune factors in saliva?

A
  • Lysozyme —-I B. cell wall
  • Lactoferrin —I Fe- dependent B.
  • IgA —–I Bac. / Virus
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17
Q

What are some specific enzymes in saliva?

A

Amylase (active pH 4-11)
Lipase (Optimal pH 4.0 (mainly stomach)
Haptocorrin
Kallikrein

18
Q

What controls saliva regulation?

A

ANS; PSN and SNS

19
Q

What can stimulate and decrease saliva regulation?

A

Increase: Sight, thought of food, nausea

Decrease: Fatigue, sleep, fear, dehydration, exercise.

20
Q

How does the PNS influence salivary glands?

A

= Accelerates secretion
Results in a large amount of watery saliva

Myoepithelial cells contract, increased blood flow

21
Q

How does the SNS influence salivary glands?

A

= Secretion of a small volume of viscous saliva containing high enzyme concentrations

dry mouth

blood vessels constrict.

22
Q

What cause xerostomia?

A

Dry Mouth

  • Mumps
  • salivary duct calculi (stones)
  • Salivary gland tumors (usually benign)
  • Sjogrens syndrome
  • Meds
23
Q

What causes hypersalivation?

A

Water brash

  • Associated with many conditions (peptic ulceration and IBD)
  • Meds
  • Toxins i.e organophosphates, arsenic
24
Q

Describe the fourth tunic of the oesophagus;

A
  • Adventitia mostly and serosa final portion
25
Q

What is the function of the oseophagus;

A

Peristalsis, thick muscular tube, collapses when empty with folds that stretch out with peristalsis.

26
Q

Describe the epithelium of the oesophagus;

A

Thick sacrificial stratified squamous (6-8 layers). Non-keratinised in humans.

Transitions into simple cuboidal/columnar as approaches stomach.

27
Q

Describe the muscularis mucosae of the oesophagus;

A

Absent/rare, develops near stomach. Longitudinal smooth muscle. aids digestion and absorption.

28
Q

Are there glands present in the oesophagus?

A

Yes. Dont need to know specific.

29
Q

Describe the muscularis externa of the oesophagus;

A
  • Two thick coats; Inner circular and outer longitudinal (with overlap).

Peristalsis -> moves bolus
Segmentation -> Churns food (circ. primary)

Pharyngeal end contains some skeletal muscle (striated) and stomach end is only smooth muscle.

Sphincters are more physiological, tonal contraction.

30
Q

What is the covering of the oesophagus?

A

Adventitia, 1-2cm before stomach it is serosa.

31
Q

What nerves supplies the oesophagus?

A

ANS. Coordinates movements involved in swallowing.

32
Q

What are some gastro-oesophogeal diseases?

A
  • Achalasia (lower sphincter doesnt relax)
  • Neurological disorders
  • Gastro-oesophogeal disease (GORD)
  • Reflux oesophagitis
  • Barrett’s oesophagus
33
Q

What are the three histologically distinct regions of the stomach;

A

Cardia: Mucous

Fundus: Parietal glands

  • HCl
  • Intrinsic factor
  • Pepsinogen
  • Somatostatin

Pylorus: Pylroic glands

  • Pepsinogen
  • Mucous
  • Gastrin
  • Somatostatin
34
Q

Describe the stomach;

A

1.5L J shaped bag, inflatable.

3 muscle layers

4 regions;

  • Cardia
  • Fundus
  • Body
  • Pylorus
35
Q

Describe the features of the stomach;

A

Muscles;

  • Longitudinal
  • Circular
  • Oblique

Rugae ; Crypts

36
Q

What cells around found in the villi of the stomach?

A
  • Simple columnar mucous cells
  • Mucous neck cells
  • Undifferentiated stem cells
  • Parietal cells
  • Chief cell
  • Enteroendocrine cells
37
Q

What is the function of the simple columnar mucous cells;

A

Secretes mucous; glycoproteins with bicarbonate act as barrier to epithelium.

Protect against;

  • Bacteria
  • pepsinogen
  • acid
38
Q

What is the function of mucous neck cells?

A

Secretes mucous in presence of food

39
Q

What is the function of the parietal cells?

A

Intrinsic factor important in Vit B12 absoprtion.

HCL sterilizes food and acidifies environment. As well as activating enzymes.

40
Q

What is the function of chief cells?

A

Releases pepsinogen

41
Q

What is the function of enteroendocrine cells?

A

i.e

G cells- Release gastrin
ECL cells - Histamine -> parietal cells
D cells- Somatostatin -> inhibits histamine and gastric production

Digestive MBChB 2 (31 decks)

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