Histology

Question 1

what is the role of the oral cavity, teeth and tongue

Answer 1

mechanical processing, moistening, mixing with salivary secretion

Question 2

what is the role of the salivary glands

Answer 2

secretion of lubricating fluid containing enzymes that break down carbohydrates

Question 3

what is the role of the pharynx

Answer 3

pharyngeal muscles propel materials into the oesophagus

Question 4

what is the role of the oesophagus

Answer 4

transport of material into the stomach

Question 5

what is the role of the stomach

Answer 5

chemical breakdown of materials via acid ans enzymes

Question 6

what is the role of the liver

Answer 6

secretion of bile (lipid digestion), storage of nutrients, many other vital functions

Question 7

what is the role of the pancreas

Answer 7

exocrine cells secrete buffers and digestive enzymes

endocrine cells secrete hormones

Question 8

what is the role of the gall bladder

Answer 8

storage and concentration of bile

Question 9

what is the role of the small intestine

Answer 9

enzymatic digestion and absorption of water, organic substrates, vitamins and ions

Question 10

what is the role of the large intestine

Answer 10

dehydration and compaction of indigestible materials in preparation for elimination

Question 11

what cells cover the oral cavity, oropharynx and laryngopharynx

Answer 11

stratified squamous epithelium- generally not keratinized

Question 12

what cells cover the nasal cavity and nasopharynx

Answer 12

respiratory epithelium

Question 13

what cells cover the anterior 2/3 of the tongue

Answer 13

stratified squamous epithelium, thin on ventral (forward) surface, thick and with papillae on the dorsal (backwards) surface

Question 14

what cells cover the posterior 1/3 of the tongue

Answer 14

smooth stratified squamous epithelium which (expect for the circumvallate) lacks papillae. Does have substantial lymphoid aggregates in the submucosa

Question 15

what are the papillae of the tonuge

Answer 15

fungiform, circumvallate, foliate, filiform

Question 16

what are the different structures present in the posterior 1/3rd of the tongue

Answer 16

stratified squamous epithelium, crypts, lymphoid tissue with some lymphoid follicles

Question 17

(from the oesophagus to the anal canal) what are the 4 main layers of the GI tract from the lumen outwards

Answer 17

mucosa,
submucosa,
muscularis externa,
serosa/ adventitia

Question 18

what are the three layers of the mucosa

Answer 18

epithelium (sits on a basal lamina)
lamina propria (loose connective tissue)
muscularis mucosae (thin layer of smooth muscle)

Question 19

what is the submucosa

Answer 19

loose connective tissue

Question 20

what is the muscularis externa

Answer 20

two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer

Question 21

what is the serosa or adventitia

Answer 21

outerlayer of connective tissue that either suspends the digestive tract or attaches it to other organs

Question 22

what are the holes in the epithelium called

Answer 22

gastric pits, at the bottom of these are gastric glands

Question 23

what lines gastric pits

Answer 23

surface mucous cells

Question 24

what are the parts of the from top to bottom

Answer 24

pit
isthmus (mostly parietal cells)
neck (mucous and stem cells)
base (chief, parietal, enteroendocrine cells)

Question 25

what is the role of the chief cell

Answer 25

digesting enzyme secreting cell

Question 26

what is the role of the parietal cells

Answer 26

hydrochloric acid producing cell

Question 27

describe the mucosa of the cardia of the stomach

Answer 27

deep gastric pits that branch into loosely packed tortuous glands

Question 28

describe the mucosa of the body of the stomach

Answer 28

shallow gastric pits with long straight gastric glands

Question 29

describe the mucosa of the pylorus of the stomach

Answer 29

deep gastric pits with branched coiled gastric glands at a higher density than in the cardia

Question 30

what is different about the muscularis externa of the stomach

Answer 30

in areas has additional layer which is oblique to the usual circular and longitudinal muscle layers, and is located internal to the circular layer. this layer aids in churning

Question 31

describe the gastroduodenal junction

Answer 31

abrupt transition from stomach mucosa to duodenal mucosa. the inner layer of circular smooth muscle is markedly thickened to form the pyloric sphincter

Question 32

what is seen on the surface view of the small intestine

Answer 32

villi and crypt of lieberkuhn

Question 33

how long is the duodenum

Answer 33

25cm

Question 34

how long is the jejunum

Answer 34

2m long

Question 35

how long is the ileum

Answer 35

2.75m

Question 36

where are peyers patches found

Answer 36

in the ileum

Question 37

describe enterocytes

Answer 37

the most numerous, tall columnar cells with a brush border, the principle absorptive cells

Question 38

describe goblet cells

Answer 38

produce mucin to protect epithelium and lubricate passage of material

Question 39

describe paneth cells

Answer 39

Found at the base of the crypts of Lieberkuhn, they have a defensive function and have a role in regulating bacterial flora (secrete lysozyme and definsins)

Question 40

describe enteroendocrine (neuroendocrine) cells

Answer 40

produce hormones that contribute to the control of secretion and motility (e.g. gastrin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP)

Question 41

describe stem cells

Answer 41

found at the base of the crypts of lieberkuhn, they divide to replenish epithelium

Question 42

how is the duodenum different from any other part of the GI tract below the oesophagus

Answer 42

has glands within the submucosa called brunners glands which produce a thin alkaline mucous to neutralised the chyme

Question 43

what type of tissue are peyers patches

Answer 43

lymphoid

Question 44

what are the two principle cell types of the large intestinal epithelium

Answer 44

``` absorptive cells (remove salt and water) goblet cells (secrete mucous to lubricate the colon) ```

Question 45

what is the appendix

Answer 45

blind ending hollow extension of the cecum

Question 46

what is the 2-3cm of the anal canal continuous with

Answer 46

the stratified squamous epithelium of the surrounding skin

Question 47

what controls gut motility

Answer 47

enteric nervous system, via myenteric plexus. most neurons in ganglia between two muscle layers of the muscularis externa

Question 48

what is the submucosal plexus

Answer 48

second network of neurons found in the submucosa that controls the muscle of the muscularis mucosae and also helps regulate secretion in the epithelium