Functional Histology of the Gut Flashcards Preview

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Flashcards in Functional Histology of the Gut Deck (51):
1

What structures does the oral cavity consist of?

salivary glands and teeth

2

What is the function of the oral cavity and what type of epithelia is present?

ingestion, fragmentation and has stratified squamous epithelium

3

What do the simple passages of the alimentary tract consist of, what's their function and what type of epithelium is present?

Oesophagus and anus, involved in transport of food and waste and has stratified squamous epithelium

4

What does the main body of the digestive tract consist of, and what is it's function?

stomach, intestines and glands which are involved in digestion and absorption

5

What type of epithelium is present in the stomach?

simple columnar epithelia

6

What type of epithelium is present in the small intestine?

simple columnar of villi

7

Name the 4 components of nutrient absorption and elimination

fragmentation, digestion, absorption and elimination

8

Describe 'fragmentation'

where food is chewed and broken down by enzymes in the oral cavity using saliva containing amylase

9

Describe 'digestion'

where food is broken down by enzymes in the stomach and duodenum

10

Describe 'absorption'

where enterocytes absorb nutrients and capillaries and lacteals transport these nutrients from the mucosa

11

Describe 'elimination'

liquid residue is passed to the colon where water is absorbed from it and solid faeces is expelled through the anal canal

12

Outline the structures that food passes through after it is ingested

mouth, oropharynx, oesophagus, stomach, duodenum, jejunum, ileum, large intenstine, anus

13

What are the four basic layers of the wall of the alimentary tract?

1) mucosa
2) submucosa
3) muscularis propria
4) serosa/adventitia

14

Describe the mucosa of the gut wall

consists of a lumen, epithelium, lamina propria and muscularis mucosae and varies with region and function

15

Describe the submucosa of the gut wall

this is a thicker layer of fibrocollaginous tissue which carries vessels and nerves as well as the submucosal neural plexus

16

Describe the muscularis propria of the gut wall

this consists of two layers; an inner circular layer and an outer longitudinal layer

17

Describe the adventitia/serosa of the gut wall

the most external part of the gut wall

18

When is the outside called the adventitia?

where the gut is retroperitoneal it is called adventitia, is referred to as serosa when intraperitoneal

19

Describe what is meant by the enteric nervous system

consists of autonomic functioning ganglia with inputs from the parasympathetic and sympathetic nervous systems

20

What does the submucosal plexus innervate?

muscularis mucosae and mucosal glands

21

What does the myenteric plexus innervate?

muscularis propria (inner circular and outer longitudinal layers)

22

Define 'MALT'

mucosa associated lymphoid tissue

23

Define 'GALT'

gut associated lymphoid tissue

24

Name four characteristics that prevent gastroesophageal reflux

the oesophagus joins the stomach at an acute angle (at the cardia), the contracn of the diaphragm on the oesophagus prevents reflux, intra-abdominal pressure on the oesophagus at rest prevents reflux, there is unidirectional peristalsis

25

Describe the mucosa in the oesophagus

non-kertainised stratified squamous epithelium

26

Describe the submucosa in the oesophagus

contains mucous glands, blood vessels, nerves, ganglion cells and lymphoid tissue

27

Describe the muscularis propria in the oesophagus

the top 1/3 is skeletal muscle to facilitate swallowing and bottom 2/3 is smooth muscle for peristalsis

28

Does the oesophagus have adventitia or serosa?

adventitia

29

Outline the gross anatomy of the stomach

cardia, body, fundus (above body), antrum, pylorus then duodenum

30

Which secretions are facilitated in the cardia of the stomach?

mucus from mucous neck cells

31

Which secretions are facilitated in the fundus/body of the stomach?

mucus from mucous neck cells, HCl and intrinsic factor from parietal cells, pepsin from chief cells and gut hormones from endocrine cells

32

Which secretion are facilitated in the pylorus of the stomach?

mainly mucus from MNC and gut hormones from endocrine cells

33

How many layers are there in the muscularis propria of the stomach?

Three instead of two: inner oblique, middle circular and outer longitudinal

34

How do parietal cells appear in a stain?

have a lot of cytoplasm and central nucleus

35

How do chief cells appear in a stain?

dark staining and are smaller

36

How do mucous neck cells appear in a stain?

small cells with light staining within the epithelium

37

What is the pyloric sphincter?

a marked thickening of the circular layer of the muscularis propria

38

Describe the structure of the duodenum

has Brunner's glands in the submucosa (secrete alkaline mucus), receives bile and pancreatic juice through the ampulla of vater controlled by the sphincter of oddi

39

Describe the structure of the jejunum

has the most specialised surface area for absorption

40

Describe the structure of the ileum

greatest amount of GALT in the form of Peyer's patches

41

What are the plicae circulares?

circular folds including the submucosa in the jejunum and ileum

42

What are villi?

extensions of the mucosa that possess the central core of the lamina propria and at their bases are the crypts of Leiberkuhn

43

What are microvilli?

apical processes known as the brush border

44

What are the crypts of Leiberkuhn

the crypts of the small intestine, which have a secretory and stem cell role

45

Describe the lamina propria of the cells of the small intestine

there is areolar connective tissue containing strands of smooth muscle from the muscularis mucosae as well as GALT

46

Which cells of the small intestine are involved in absorption?

villus enterocytes

47

Which cells of the small intestine are involved in secretion?

crypt enterocytes

48

What types of cells are found in the crypts of Leiberkuhn in the small intestine?

endocrine cells, stem cells (involved in epithelium regeneration) and paneth cells (secrete antimicrobial agents)

49

Describe the histology of the large intestine

abundant goblet cells, no villi, and the outer longitudinal muscularis propria is organised into 3 bundles known as taeniae coli which act to sacculate the colon and form haustra

50

What is taeniae coli?

three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colon

51

What is haustra?

small pouches which give the colon its segmented appearance