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Flashcards in histology of the gut Deck (76):
1

name the functional compartments of the alimentary tract and their function

oral cavity - ingestion and fragmentation

simple passages (oesophagus and anus) - transport of food/waste

digestive tract (stomach and intestine) - digestion/absorption

2

what type of epithelium is found in the oral cavity?

stratified squamous

3

what type of epithelium is found in the simple passages?

stratified squamous

4

what makes up the digestive tract?

mucosal glands
accessory glands like pancreas and liver
enterocytes

5

describe the stages of absorbing nutrients from ingested food from top to bottom

fragmentation
digestion
absorption
elimination

6

where does fragmentation of food occur and what aids it?

oral cavity and stomach

aided by saliva from the salivary glands

7

where does digestion occur and what aids it?

starts in the stomach but continues down the duodenum

pancreatic enzymes, bile salts and brush border enzymes

8

where does absorption occur and what aids it?

mostly in the jejunum and the ileum

enterocytes absorb nutrients
capillaries and lacteals transport these from the mucosa

9

where does elimination occur?

colon and anal canal

10

where is water absorbed from liquid residue?

colon

11

where is solid faeces expelled from?

the anal canal

12

what are the four layers of the gut?

mucosa
submucosa
muscularis propria
adventitia/serosa

13

what are the layers of the mucosa?

epithelium
lamina propria
muscularis mucosae

14

what makes up the submucosa

a thick layer of fibrocollagenous tissue

15

what is a feature of the fibrocollagenous tissue?

shock absorbing

16

what does the submucosa carry?

vessels and nerves and the submucosal neural plexus

17

what are the layers of the muscular propria?

inner circular
outer longitudinal

18

where is adventitia found?

where the gut is retroperitoneal

most of the oesophagus
duodenum
ascending and descending colon
rectum

19

what gives input to the enteric nervous system?

parasympathetic and sympathetic systems

20

what are the two plexuses of the enteric nervous system?

myenteric plexus
submucosal

21

what does the submucosal plexus innervate?

muscularis mucosae
mucosal glands

22

what does the myenteric plexus innervate?

muscularis propria

23

what does MALT stand for?

mucosa associated lymphoid tissue

24

what does MALT contain?

intraepithelial lymphocytes
lymphocytes
plasma cells of the lamina propria - IgA production
lymphoid follicles

25

name the main structures of the alimentary tract

mouth
oropharynx
oesophagus
stomach
small intestine
large intestine
anus

26

what is the main function of the oesophagus?

transport of fragmented food

27

what does swallowing involve?

relaxation of cricopharyngeal part of inferior constrictor muscle

28

what mediates peristalsis?

smooth muscle

29

what type of epithelium is found in the mucosa of the oesophagus?

nonkeratinised stratified squamous epithelium

30

what does the submucosa of the oesophagus contain?

mucous glands
blood vessels
nerves and ganglion cells
lymphoid tissue

31

describe the parts of the muscularis propria of the oesophagus and their function

top 1/3 - skeletal for swallowing

bottom 1/3 - smooth for peristalsis

32

what is the oesophagogastric junction?

the junction between the oesophagus and the stomach

33

how does the mucosa change at the oesophagogastric junction?

goes from stratified squamous to simple columnar

34

what is the function of the stomach?

acting in mechanical and chemical digestion

35

what does glandular mucosa in the stomach do?

produce gastric juice which helps reduce contents to chyme

36

what is the mucosa in the stomach covered in and why?

thick layer of mucous for protection from stomach acid

37

what are the parts of the stomach?

cardia
funds
body
pylorus

38

what are rugae?

ridges formed by the non-distended mucosa of the stomach

39

which cells in the stomach secrete mucus?

columnar surface
mucous neck cells

40

what substances are secreted into the stomach?

gastric acid
intrinsic factor
pepsinogen

41

what regenerates epithelium?

stem cells

42

how many layers to the muscularis propria in the stomach and what are they?

3
inner oblique
middle circular
outer longitduinal

43

what is the pyloric sphincter?

thickening of the muscularis propria at the gastroduodenal junction

44

what are the functions of the small intestine?

continues the digestion started in the stomach

absorbs molecules from digested food

45

what are the parts of the small intestine?

duodenum
jejenum
ileum

46

what is the function of the duodenum?

digestion continues from the stomach

47

what glands are found in the duodenum and what do they secrete?

Brunner's glands in the submucosa
secrete alkaline mucus in response to luminal chyme

48

what does the duodenum receive and what does it receive this from?

bile and pancreatic juice via the Ampulla of Vater

49

what controls the Ampulla of Vater?

the Sphincter of Oddi

50

what is the function of the jejunum?

most absorption occurs here

51

what is the function of the ileum?

absorption

52

how is the surface area for absorption increased in the small intestine?

plicae circulares
villi
microvilli

53

what are plicae circulares?

circular folds in the submucosa in the jejunum and ileum

54

what are vili?

extensions of the mucosa

55

what is found at the base of vili?

the intestinal glands (crypts of Lieberkuhn)

56

what is the brush border?

the apical processes on cells

57

what do microvilli do?

aids terminal digestion of proteins and carbohydrates

58

what connective tissue is in the lamina propria of villi?

areolar connective tissue

59

what is the function of enterocytes in the lining villus?

digestion using brush border enzymes and absorption

60

what is the function of enterocytes in the crypts?

secretion of watery intestinal juice

61

what is the function of goblet cells?

mucus secretion for protection/lubrication

62

where are goblet cells found in the small intestine?

scattered along villus

63

how does the distribution of goblet cells change along the digestive tract?

increase in numbers distally

64

where are endocrine cells found in the small intestine?

crypt

65

what is the function of endocrine cells?

regulation of gut function
secrete motilin

66

what is the function of stem cells?

regeneration of epithelium

67

where are stem cells found in the small intestine?

crypt

68

where are paneth cells found in the small intestine?

crypt

69

what is the function of paneth cells?

antimicrobial agents
defensives
lysozyme

70

how is the large intestine specialised for its functions?

enterocytes - water and salt absorption
mucus secretion - abundant goblet cells

71

where are villi found?

only in the small intestine

72

what are the taenia coli?

3 longitudinal bundles of muscularis propria of the large intestine

73

what are haustra?

small pouches of the colon

74

what is sacculation?

sac formation

75

what is the function of the taeniae coli?

act to sacculated the colon to form haustra

76

why are the posterior aspects of the ascending and descending segments covered in adventitia?

bc they're retroperitoneal