L27 - GI tract microanatomy

Question 1

What type of epithelium lines the oesophagus

Answer 1

Stratified squamous non keratinising epithelium

Question 2

What do the oesophageal glands in the submucosa secrete

Answer 2

An equal amount of serous and mucus

Question 3

what epithelium lines stomach

Answer 3

simple columnar

Question 4

shape of gastric glands (stomach)

Answer 4

compound tubular

Question 5

what do glands of the gastro-oesophageal junction secrete and what is the function of these secretions

Answer 5

mucus

coats stomach with protective layer

Question 6

how many types of gastric glands

what are their names

Answer 6

3
gastric glands
brunners glands
gland of crypt of lieberkuhn

Question 7

what are folds in the gastric mucosa called and what is their function

Answer 7

rugae

accumulate different volumes

Question 8

what do gastric glands of stomach secrete

Answer 8

hcl
mucus
zymogen granules

Question 9

visual characteristics of parietal cells

Answer 9

rounded
central nucleus
pink (eosinophilic)

Question 10

what do stomach parietal cells secrete

Answer 10

HCL

intrinsic factor

Question 11

function of intrinsic factor

Answer 11

aids vitamin b12 absorption

Question 12

visual characteristics of chief cells

Answer 12

speckled (zymogen granules)

purple (basophilic)

Question 13

what colour do chief cells stain

what colour do parietal cells stain

Answer 13

purple

pink

Question 14

what layer are stomach glands in

Answer 14

mucosa

Question 15

what layer are crypts of L found in

Answer 15

lamina propria (mucosa)

Question 16

example of specialisation of duodenum epithelial cells and what it does

Answer 16

microvilli to increase SA

Question 17

what do brunners glands (of duodenum ) secrete

Answer 17

thin alkaline mucus

secretin into crypts

Question 18

function of the crypts of Lieberkuhn?

Answer 18

1. release protective enzymes (paneth cells)
2. secrete hormones (enteroendocrine cells)
3. cell replacement (stem cells) (MAINLY)

Question 19

what are folds of mucosa of small intestine called and what is their function

Answer 19

plica circulares

increase SA

Question 20

why does colon contain many goblet cells

Answer 20

Lubrication to ease passage of semi solid waste material

Question 21

What is the function of the lymphoid tissue in the colon

Answer 21

inflammatory response

Question 22

in what regions can glands be sometimes found in submucosa

Answer 22

oesophagus and duodenum

Question 23

what parts of the tract have no glands in the submucosa

Answer 23

stomach
ilium
jejunum

Question 24

what are the 5 phases of the GI tract

Answer 24

1. ingestion
2. fragmentation
3. digestion
4. absorption
5. elimination

Question 25

name the 4 layers of the GI tract

Answer 25

1. mucosa (lumen) 2. submucosa 3. muscularis externa (/propria) 4. adventitia (outer)

Question 26

what are the 3 layers of the mucosa

Answer 26

1. specialised surface epithelium (innermost) 2. lamina propria 3. muscularis mucosae (outer, in contact with submucosa)

Question 27

describe the lamina propria

Answer 27

loose connective tissue contains blood and lymph vessels contains nerve fibres contains smooth muscle

Question 28

what does the epithelium of the mucosa layer rest on?

Answer 28

basal lamina

Question 29

describe the muscularis mucosae

Answer 29

thin double layer of smooth muscle

Question 30

what is the muscularis mucosae SM controlled by?

Answer 30

Meissner’s (submucosal) plexus (PNS)

Question 31

what are the roles of the mucosa epithelium in different parts of the body?

Answer 31

protective - mouth/pharynx/oesophagus/anal canal secretory - stomach absorptive - SI absorptive&protective - LI

Question 32

describe the structure (and components) of the submucosa

Answer 32

- loose connective tissue - contains blood vessels - contains nerves which form the Meissner’s (submucosal) plexus - contains leukocytes - contains variable amounts of lipids -glands in oesophagus

Question 33

where is the Meissner’s plexus located

Answer 33

submucosa

Question 34

how is the submucosa of the oesophagus and duodenum different to the rest of the GI tract

Answer 34

can contain glands

Question 35

describe the structure of the muscularis externa

Answer 35

2 thick SM layers - inner circular - outer longitudinal

Question 36

how does the structure of the muscularis externa differ in the stomach from the rest of GI tract

Answer 36

has 3 layers in the stomach rather than 2

Question 37

what is found between the two layers of the muscularis externa

Answer 37

(auerbachs) myenteric plexus.

Question 38

function of the muscularis externa

Answer 38

responsible for peristaltic waves

Question 39

describe adventitia structure

Answer 39

thin connective tissue continuous with surrounding organs

Question 40

what epithelium is the adventitia and what is its correct name

Answer 40

simple squamous | mesothelium

Question 41

function of mesothelium

Answer 41

bounds adventitia to cavity

Question 42

how does the muscularis externa differ down the oesophagus

Answer 42

starts as skeletal then gradually smooth as initiation of swallowing is voluntary

Question 43

how does epithelium change from the oesophagus to the stomach

Answer 43

stratified squamous to simple squamous to simple columnar

Question 44

what are the layers of muscularis externa in the stomach

Answer 44

1. oblique layer (inner, in contact with stomach contents) 2. circular layer 3. outer longitudinal layer

Question 45

name the 3 regions of the stomach

Answer 45

fundus (food first arrives) body antrum

Question 46

properties of the cardia mucosa

Answer 46

mucous secreting | few glands

Question 47

properties of the fundus/body mucosa

Answer 47

densely packed glands secreting mucus, gastric juice, acid and enzymes

Question 48

what is secreted from glands in the fundus

Answer 48

mucus acid gastric lipase

Question 49

properties of the pyloric mucosa

Answer 49

deep gastric pits mucus secreting glands endocrine glands secreting gastrin

Question 50

how are gastric pits formed and what are they connected to

Answer 50

invaginations of the epithelium | glands

Question 51

what cells types are found in gastric pits and glands?

Answer 51

1. surface mucus cells 2. mucus neck cells 3. stem cells 4. endocrine cells 5. parietal cells 6. chief cells

Question 52

function of gastric surface mucus cells

Answer 52

secrete mucus and bicarbonate to protect from stomach acid

Question 53

where are gastric mucous neck cells located and what do they do

Answer 53

upper parts of the gastric glands | secrete mucus

Question 54

where are gastric stem cells located

Answer 54

neck region of gland

Question 55

function of gastric endocrine cells in glands

Answer 55

secrete gastrin + somatostatin (hormones)

Question 56

where in the gastric gland are parietal cells located and what are their function

Answer 56

throughout the gland 1. make and secrete HCL 2. secrete intrinsic factor

Question 57

where in gastric glands are chief cells located and what is their function

Answer 57

``` lower regions secrete zymogens (enzymes) in response to gastrin ```

Question 58

what layer of the SI would you find plicae circularis

Answer 58

mainly mucosa sometimes submucosa

Question 59

what is found on the plicae circularis?

Answer 59

villi which have a brush border or microvilli

Question 60

what surface epithelium do villi have

Answer 60

simple columnar

Question 61

what is found within villi

Answer 61

goblet cells endocrine cells blood vessels micrvilli lining

Question 62

what lines microvilli

Answer 62

glycocalyx coating - wherever there is no cilia

Question 63

in what layer of the duodenum are brunners glands

Answer 63

submucosa

Question 64

what cells are found in the crypts of L

Answer 64

stem cells paneth cells enteroendocrine cells

Question 65

where are crypts of L located

Answer 65

between villi | from pyloric mucosa of stomach to colon

Question 66

where are paneth cells located and what is their function

Answer 66

lower 1/3 of crypt | release protective enzymes to destroy bacteria

Question 67

how are enteroendocrine cells stimulated and what do their hormones stimulate

Answer 67

by acidic chyme from stomach enzyme secretion release of bile from gall bladder

Question 68

what part of the SI has the tallest villi

Answer 68

jejunum

Question 69

order of large intestine

Answer 69

``` caecum appendix ascending colon transverse colon descending colon sigmoid colon rectum anal canal ```

Question 70

what is different about the muscularis externa layer of the colon

Answer 70

the outer longitudinal layer has 3 bands called tenia coli for powerful peristalsis of solid faeces

Question 71

role of the muscularis mucosae in the colon

Answer 71

prevents clogging of glands and helps mucus expulsion

Question 72

how do the no. of goblet cells increase throughout the GI tract

Answer 72

increase towards rectum

Question 73

what epithelium in anal canal

Answer 73

stratified squamous

Question 74

where are peyers patches found

Answer 74

musosa (lumen) of ileum mainly

Question 75

function of peyers patches

Answer 75

removal of pathogens

Question 76

what are peyers patches

Answer 76

bulging lymphoid follicles

Question 77

what is MALT and where is it found

Answer 77

mucus associated lymphoid tissue | in mucosa layer