Flashcards in Histology Deck (39):
1
What type of epithelium is the oral cavity, oropharynx and laryngopharynx covered by
Generally non-keratinised (Except hard palate and gingiva) stratified squamous epithelium
2
What type of epithelium is the nasal cavity and nasopharynx covered by?
Respiratory epithelium
3
What type of epithelium covers the anterior 2/3rds of the tongueHow does this vary between the ventral and dorsal surface
Stratified squamous epithelium Thin on ventral surfaceThick with papillae on the dorsal surface
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Epithelium on the posterior 1/3rd of the tongue
Smooth stratified squamous epithelium which lacks papillae, except the circumvallate papillae, but does have some lymphoid follicles in the submucosa
5
What are the 4 types of taste buds present on the tongue?
FungiformCicumvallateFoliateFiliform (no tastebuds - occupy much of the dorsal surface of the tongue)
6
What are the 4 major layers of the digestive tract (from the oesophagus to the anal canal)
Mucosa (epithelium, lamina propria, muscularis mucosae)SubmucosaMuscularis externaSerosa or adventitia
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What are the 3 layers of the mucosa?
Epithelium (sits on a basal lamina)Lamina propria (loose connective tissue)Muscularis mucosae (thin layer of smooth muscle)
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What is the submucosa
Loose connective tissue
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What is the muscularis externa
2 thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer)
10
What is the serosa or adventitia
An outer layer of connective tissue that ether suspends the digestive tract or attaches it to other organs
11
What happens in terms of the epithelium at the cardia of the stomach
There is an abrupt transition from stratified squamous epithelium of the oesophagus t to simple columnar epithelium of the stomach
12
What are the holes in the surface of the stomach and what is at the bottom of these
Holes = gastric pitsThere are 1-7 gastric glands at the bottom of these
13
What are gastric pits lined by
Surface mucous cells
14
In terms of the cells gastric gland, what does the pit contain mostly?Isthmus?Neck?Base?
Pit = surface mucous cellsIsthmus = parietal cellsneck = neck mucous cells and stem cellsBase = chief cells (few parietal cells and neuroendocrine cells)
15
What are chief cells of gastric glands?
digestive enzyme secreting cells
16
What are parietal cells of gastric glands
HCl acid producing cells
17
How does the mucosa of the stomach differ across the cardia, body and pylorus?
The cardia contains deep gastric pits that branch into loosely packed, tortuous glandsThe body contains shallow gastric pits with long straight gastric glandsThe pylorus contains deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia
18
What is unusual about the muscularis externa of the stomach?
It contains an additional oblique layer which located internal to the circular layer and aids in the churning action of the stomach
19
What creates the pyloric sphincter?
The inner circular layer of smooth muscle is markedly thickened
20
Epithelium of the small intestine
Simple columnar epithelium with villi and tubular glands
21
Epithelium of the large intestine
Simple columnar epithelium with tubular glands
22
What are the crypts called between the bases of adjacent villi in the small intestine?
Crypts of Lieberkuhn
23
What makes the duodenum different from any other region of the GI tract
It contains glands within the submucosa called Brunner's glands which when stimulated by the presence of chyme, produce a thin, alkaline mucous to neutralise the chyme
24
What part of the small intestine has the tallest villi
The jejunum (located on the plicae circulars)
25
What are the permanent circular folds on the mucosa and submucosa of the small intestine (except the first part of the duodenum) called?
Plicae Circularis (these are not just folds of the mucosa, but also contain submucosa)
26
What are the cells of the small intestinal epithelium
EnterocytesGoblet cellsPaneth cellsNeuroendocrine cellsStem cells
27
What are enterocytes
Most numerous cell in small intestinal epitheliumTall columnar cells with a brush border Principle absorptive cell
28
What are goblet cells
Produce mucin to protect epithelium and lubricate passage of material
29
What are paneth cells
Found at the base of the crypts of Lieberkuhn and have a defensive function and role in regulating bacterial flora (secrete lysozyme and definsins)
30
What do neuroendocrine cells produce?
Hormones that contribute to the control of secretion and motility e.g. CCK, gastrin, VIP
31
Purpose of stem cells in small intestinal epithelium
Found at the base of the crypts of LieberkuhnDivide to replenish the epithelium
32
What does GALT stand for?
Gut associated lymphoid tissue - the gut has a substantial amount of lymphoid tissue associated with it
33
What are Peyer's patches
Areas of relatively large aggregations of lymphoid tissue, particularly in the ileum
34
What are the 2 principal cell types present in the epithelium of the large intestine
Absorptive cells - for removal of salts and thereby waterGoblet cells - for the secretion of mucus to lubricate the colon (these are arranged in straight tubular glands referred to as crypts that extend down to the muscularis mucosae
35
What is different about the outer, longitudinal smooth muscle in the large intestine
Is not continuous but instead found in 3 muscular strips called teniae coli
36
What is different about the structure of the appendix compared to the rest of the colon
The crypts are far less abundantThere is typically a circular arrangement of lymphoid tissue in the submucosa and often the lamina propria (the lymphoid tissue tends to decline with age)
37
What type of epithelium does the anal canal have
Stratified squamous epithelium
38
Where do most of the neurones of the enteric nervous system live?What is this interconnected of fibres called?What does it control?
In groups called ganglia between the 2 muscle layers that make the muscularis externaMyenteric plexusGut motility
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