GI tract

Question 1

what are the 3 types of oral mucosa?

Answer 1

• lining mucosa
• masticatory mucosa
• specialized mucosa

Question 2

what does oral mucosa consist of?

Answer 2

1. Stratified squamous epithelium.
2. Lamina propria of dense connective tissue
3. Submucosa of loose connective tissue

Question 3

where is masticatory mucosa found?

Answer 3

covering the hard palate and the gingiva (gums around the teeth). The epithelium here is keratinized or parakeratinized

Question 4

where is lining mucosa found?

Answer 4

Inside of the lips, lining the buccal surfaces, covering the soft palate and lining the floor of the mouth and the inferior surface of the tongue. The epithelium here is not keratinized

Question 5

what is the epithelium of the tongue?

Answer 5

Anterior 2/3: Stratified squamous epithelium, thin on ventral surface, thick and with papillae on the dorsal surface.

Posterior 1/3: Covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papillae but does have substantial lymphoid aggregates in the submucosa

Question 6

what covers the dorsal surface of the tongue?

Answer 6

keratinized stratified squamous epithelium with a dense irregular connective tissue lamina propria that ties the epithelium to the underlying muscle

Question 7

what are the 4 types of tongue papillae?

Answer 7

• Filiform
• fungiform
• foliate
• circumvallate

Question 8

what are the muscles in the tongue?

Answer 8

• extrinsic skeletal muscles

- intrinsic skeletal muscles bundles in longitudinal, transverse and vertical planes

Question 9

what is covered by stratified squamous epithelium which is generally not keratinized?

Answer 9

Oral cavity, oropharynx and laryngopharynx

Question 10

what covers the nasal cavity and nasopharynx?

Answer 10

respiratory epithelium

Question 11

what are the 4 major layers (starting from the lumen and going out) that make up the digestive tract from the oesophagus to the anal canal?

Answer 11

1. Mucosa: 3 parts
2. Submucosa: loose connective tissue
3. Muscularis Externa: two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
4. Serosa or Adventitia: outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs

Question 12

what are the 3 parts of the mucosa?

Answer 12

a. Epithelium: sits on a basal lamina
b. Lamina Propria: loose connective tissue
c. Muscularis Mucosae: thin layer of smooth muscle

Question 13

what is the gastro-oesophageal junction?

Answer 13

Abrupt transition from stratified squamous epithelium of oesophagus to the simple columnar epithelium of the cardia of the stomach

Question 14

what lines gastric pits?

Answer 14

mucous cells

Question 15

what is a chief cell?

Answer 15

digestive enzyme secreting cell

Question 16

what is parietal cell?

Answer 16

hydrochloric acid producing. cell

Question 17

what aids the churning action of the stomach?

Answer 17

The muscular external layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer

Question 18

what is the gastroduodenal junction?

Answer 18

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

Question 19

what are the cells of the small intestinal epithelium?

Answer 19

• enterocytes
• goblet cells
• paneth cells
• Neuroendocrine cells
• Stem cells

Question 20

what does the duodenum do?

Answer 20

receives the acidic, partly digested semifluid material called chyme from the stomach

Question 21

what happens when Brunner glands are stimulated?

Answer 21

stimulated by the presence of chyme they produce a thin, alkaline mucous to neutralise the chyme

Question 22

what are the 3 regions of the small intestine ?

Answer 22

Duodenum: Contains Brunner’s glands in the submucosa.

Jejunum: Tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae circularis. Lymphoid follicles infrequent.

Ileum: Characterized by shorter villi and aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and often extending into the lamina propria

Question 23

what are the two principal cell types of the large intestinal epithelium?

Answer 23

Absorptive cells: For removal of salts and thereby water

Goblet cells: For the secretion of mucus to lubricate the colon

Question 24

what is the rectoanal junctions?

Answer 24

There is a distinct junction between the mucosa of the rectum and the non-keratinized stratified squamous epithelium of the anal canal

Question 25

what is the nervous system of the digestive tract called?

Answer 25

enteric nervous system

Question 26

Describe the enteric nervous system.

Answer 26

This interconnected network of fibres has two plexuses, one in the submucosa (submucosal) and one between the muscle layers of the muscularis externa (myenteric)

Question 27

what plexus controls gut motility?

Answer 27

myenteric plexus

Question 28

what plexus controls the muscle of the muscles mucosae and also helps regulate secretion in the epithelium?

Answer 28

submucosal plexus

Question 29

what are the variations in mucosa?

Answer 29

• Protective: non-keratinized stratified squamous epithelium
• Secretory: simple columnar epithelium with extensive tubular glands
• Absorptive: simple columnar epithelium with villi & tubular glands
• Protective & absorptive: simple columnar epithelium with tubular glands