GI Tract Microanatomy Flashcards

1
Q

What is the inner lining of the GI tract called?

A

Mucosa

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2
Q

What is the support layer of the GI tract called?

A

Submucosa

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3
Q

What is the muscle layer of the GI tract called?

A

Muscularis externa/propria

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4
Q

What is the outer wrapping of the GI tract called?

A

Adventitia/serosa

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5
Q

Name the 4 layers of the GI tract from lumen outwards

A

Mucosa
Submucosa
Muscularis externa/propria
Adventitia/serosa

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6
Q

What 4 things make up the mucosa?

A

Epithelium, basement membrane, lamina propria, muscularis mucosa

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7
Q

What is the role of the lamina propria?

A

Supports the epithelium structurally and nutritionally

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8
Q

What type of epithelium lines the oral cavity, pharynx, oesophagus and anal canal?

A

Protective

Stratified squamous, non keratinising

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9
Q

What type of epithelium lines the stomach?

A

Secretory

Simple or branched tubular glands

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10
Q

Describe some features of the epithelium of the small intestine

A

Absorptive
Villi and crypts lines by columnar cells called enterocytes
Goblet cells producing mucus

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11
Q

Describe some features of the epithelium of the large intestine

A

Absorptive and protective
High number of goblet cells for lubrication
Presence of enterocytes

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12
Q

What is the submucosa made up of?

A

Connective tissue, blood vessels, lymphatics and nerves
Some glands
Submucosal (Meissner’s) plexus

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13
Q

What does the submucosal plexus innervate?

A

Glands

Muscularis mucosa

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14
Q

What is the muscularis externa/propria made up of?

A

Smooth muscle

Myenteric (Auerbach’s) plexus

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15
Q

What process does the myenteric plexus modulate?

A

Peristalsis

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16
Q

What is adventitia?

A

The outer wall of the gut tube, made up of a thin layer of connective tissue

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17
Q

What is serosa and where is it associated with?

A

A serous membrane covering the GI tract

Peritoneum

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18
Q

What kind of epithelium makes up a serous membrane?

A

Squamous epithelial cells secreting a small amount of fluid

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19
Q

What is a sphincter?

A

Thickening of the smooth muscle in the GI tract

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20
Q

Name the 4 sphincters of the GI tract

A

Oesophageogastric
Pyloric
Ileocaecal
Internal anal

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21
Q

Gut associated lymphoid tissue (GALT) is located in the …

A

Lamina propria

22
Q

What are Peyer’s patches and where in the GI tract are they located?

A

Collections of lymphoid follicles

Ileum

23
Q

The oral cavity and pharynx only have which 2 of the 4 layers?

A

Mucosa and submucosa

24
Q

Which part of the mucosa is not present in the oral cavity and pharynx ?

A

Muscularis mucosa

25
Q

Name the 3 paired salivary glands

A

Parotid
Submandibular
Sublingual

26
Q

All 3 paired salivary glands consist of …

A

Lobules of acini and ducts, divided by connective tissue septa

27
Q

The tongue is a bulk of interlaced bundles of … covered by …

A

Skeletal muscle

Oral epithelium

28
Q

Describe the pattern of the muscularis layer of the oesophagus

A

Skeletal in the first third
Smooth in the last third
Mixed in the middle third

29
Q

Describe the change in epithelium at the gastro-oesophageal junction

A

Changes from squamous to columnar epithelium (glandular)

30
Q

What type of epithelium is the luminar surface of the stomach made up of

A

Columnar epithelium mucous cells

31
Q

The oblique layer is an additional muscle layer lining which organ

A

Stomach

32
Q

What 4 types of cells line the gastric pits and glands

A

Mucous cells
Parietal cells
Chief cells
Enteroendocrine cells

33
Q

What do the mucous cells of the gastric pits and glands produce?

A

Mucous and bicarbonate

34
Q

What do the parietal cells of the gastric pits and glands produce?

A

HCl and intrinsic factor

35
Q

What do the chief cells of the gastric pits and glands produce?

A

Enzymes such as pepsinogen

36
Q

What do the enteroendocrine cells of the gastric pits and glands produce?

A

Hormones such as gastrin

37
Q

What epithelium lines the villi of the small intestine?

A

Simple columnar epithelium

38
Q

What is the function of enterocytes in the SI epithelium?

A

Absorption

Brush border enzymes aid digestion

39
Q

What is the function of goblet cells in the SI epithelium?

A

Secrete mucus

40
Q

What is the function of paneth cells in the SI epithelium?

A

Release defensins to protect against infection

41
Q

What is the function of enteroendocrine cells in the SI epithelium?

A

Secrete locally acting hormones regulating secretion and motility

42
Q

What is the function of stem cells in the SI epithelium?

A

Divide and replace the different cells contained in the SI epithelium

43
Q

The anal canal is a muscular canal controlled by 2 …

A

Sphincters

Internal and external

44
Q

Whats the difference between the internal and external anal sphincter

A

Internal- Smooth muscle, involuntary control

External- Skeletal muscle, voluntary control

45
Q

Change in epithelium from the rectum to anus

A

Columnar to stratified squamous

46
Q

… are responsible for the lubrication of passage of faeces

A

Anal glands

47
Q

Define exocrine

A

Containing glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood.

48
Q

Define endocrine

A

Containing glands which secrete hormones or other products directly into the blood.

49
Q

What are acini

A

Clusters of secretory cells (columnar) that surround ducts

50
Q

What is secreted by the duct epithelial cells in the pancreas

A

Bicarbonate ions and water (together make pancreatic juice)