Histology Flashcards

1
Q

what 4 layers make up the basis of the GI tract?

A

Mucosa
Submucosa
Muscularis externa
Serosa/Adventitia

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2
Q

what is the mucosa made up of?

A

Mucous membrane
Lamina propria
Muscularis mucosae

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3
Q

describe what the submucosa generally contains.

A

CT, larger blood and lymph vessels, glands and submucosal plexus

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4
Q

describe what the mucosa generally contains.

A

Mucous membrane containing epithelium and maybe gland cells
Lamina propria containing loose CT, capillaries, enteric neurons and lymphoid tissue
Muscularis mucosae which is a thin layer of smooth muscle

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5
Q

describe what the muscularis externa generally contains.

A

Circular muscle, longitudinal muscle with the myenteric plexus inbetween

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6
Q

describe what the serosa generally contains.

A

CT which either suspends or attaches the organ to other organs

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7
Q

what are the varying functions of the mucosa throughout the GIT?

A

Proctective, secretory, absorptive

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8
Q

what type of epithelium it the oral cavity, pharynx, oesophagus and anal canal lined with?

A

Non-keratinised stratified squamous

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9
Q

what type of epithelium lines the stomach?

A

simple columnar epithelium with extensive tubular glands

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10
Q

which type of epithelium lines the small intestine?

A

simple columnar epithelium with villi and tubular glands

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11
Q

which type of epithelium lines the large intestine?

A

simple columnar epithelium with tubular glands

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12
Q

what is the sulcus terminalis?

A

a v-shaped depression separating the anterior and posterior parts of the tongue

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13
Q

what are the differences in the histology of the anterior 2/3 and posterior 1/3 of the tongue?

A

Anterior is thick with papillae on the dorsal surface

Posterior is smooth and lacks papillae (except circumvallate) BUT has lots of lymphoid aggregates in the submucosa

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14
Q

what are the 4 types of papillae found on the tongue?

A

Filiform
Fungiform
Circumvallate
Foliate

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15
Q

describe structure of filiform papillae.

A

conical, elongated projections of CT covered with highly keratinised stratified squamous epithelium

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16
Q

Which papillae is the smallest and most frequent?

A

filiform

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17
Q

describe the structure of the fungiform papillae.

A

mushroom shaped projections scattered amongst the filiform papillae

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18
Q

where are fungiform papillae located?

A

all over the anterior tongue but mostly at the tip

19
Q

where are the filiform papillae located?

A

all over the anterior tongue

20
Q

describe the structure of the circumvallate papillae.

A

large, dome-shaped structures surrounded by moat-like invaginations, which contain numerous taste buds.

21
Q

where are circumvallate papilae located?

A

just anterior to the sulcus terminalis

22
Q

how many circumvallate papillae are there?

A

8-12

23
Q

where are foliate papillae located?

A

on the posterior lateral edges of the tongue

24
Q

describe the structure of the foliate papillae

A

parallel low ridges separated by deep mucosal clefts aligned at right angles to the long axis of the tongue

25
Q

which papillae have taste buds?

A

fungiform, foliate and circumvallate

26
Q

which type of papillae become less frequent with time?

A

Foliate papillae

27
Q

what surrounds the entrance to the oesophagus?

A

a ring of lymphoid tissue made up of palatine, lingual, tubal and pharyngeal tonsils

28
Q

what causes the lumen of the oesophagus to appear branches?

A

the longitudinal folds in the mucosa

29
Q

what distinguished the oesophagus histologically from other parts of the GIT?

A

it has submucosal glands

30
Q

what type of muscle makes up the upper 1/3 and lower 1/3 of the oesophagus?

A

upper 1/3 = striated muscle (continuation from pharynx)

lower 1/3 = smooth muscle

31
Q

what innervates the upper and lower parts of the oesophagus?

A

Upper: somatic motor neurons of vagus
Lower: visceral motor neurons of vagus

32
Q

what change is seen at the gastro-oesophageal junction in the mucosa?

A

epithelium changes from stratified squamous to simple columnar epithelium.

33
Q

what are the rugae of the stomach composed of?

A

mucosa and submuscosa

34
Q

what lines the surface of the stomach and the gastric pits?

A

surface mucous cells (epithelial cells with mucous granules in a cup at the apical end)

35
Q

how do prostaglandins protect and repair the mucosa of the stomach?

A

by stimulating secretion of bicarbonate and increasing the thickness of the mucosa causing vasodilation of the lamina propria to improve nutrient delivery to the damaged area, optimising repair

36
Q

what effect does aspirin have in the stomach?

A

it supresses the production of prostaglandins and if it gets in direct contact with the stomach wall it interferes with hydrophobic properties of the gastric mucosa

37
Q

Into which layer do the gastric glands extend down into?

A

the muscularis mucosae

38
Q

the cells of the gastric glands create gastric juice, what does this contain?

A

HCl
Pepsin
Mucous
Intrinsic factor

39
Q

what do chief cells in the gastric glands secrete?

A

pepsinogen

40
Q

what is the intrinsic factor produced by parietal cells in the gastric glands?

A

a glycoprotein which binds to B12 allowing its absorption

41
Q

what do enteroendocrine cells produce and what is their function?

A

Gastrin and other hormones which are secreted into the lamina propria where they enter circulation and act locally on other gastric cells

42
Q

how do the gastric pits and glands differ in the different parts of the stomach?

A
Cardia = deep gastric pits branching into loosely packed torturous glands
Fundas = shallow gastric pits with long straight gastric glands
Pylorus = deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia
43
Q

which part of the GIT has an additional muscle (to the circular and longitudinal) layer and why?

A

stomach, to aid in the churning action