General histology of GIT

Question 1

what is the function of gastrointestinal tract

Answer 1

to break down food for absorption into the body.

Question 2

Four layers of GIT

Answer 2

Mucosa
Submucosa
Muscularis propria
Adventitia

Question 3

Where does GIT start and end

Answer 3

from mouth to anus

Question 4

components of mucosa

Answer 4

Epithelium
Supporting Lamina propria
Smooth muscle layer – muscularis mucosae

Question 5

what does these components do?

Answer 5

These components produces local movement and folding of the mucosa.

Question 6

List and describe the four points of mucosa.

Answer 6

Gastro-oesophageal junction- stratified squamous epithelium in the oesophagus becomes simple columnar epithelium in the stomach
Gastroduodenal junction- long pits and short, coiled glands in the pyloric stomach to villi and crypts in the duodenum
Ileocecal junction- villi with crypts in the small intestine to only crypts in the large intestine
Rectoanal junction-simple columnar epithelium in the rectum to stratified squamous epithelium in the anus

Question 7

submucosa is a layer of loose connective tissue, it has … and supports….?

Answer 7

it supports mucosa and has large vessels, nerves and lymphatics

Question 8

muscularis propria has two layers arranged as ?

Answer 8

inner circular and outer longitudinal which contribute to peristaltic contraction.

Question 9

adventitia is often referred as ? and why?( outer layer of loose connective tissue)

Answer 9

Referred to as serosa – outer connective tissue layer lined by mesothelium and covers structures in the peritoneal cavity.
it also conducts nerves, major vessels and contain adipose tissue.

Question 10

Contraction of smooth muscle is initiated by pacemaker cells known as ?

Answer 10

interstitial cells of Cajal

Question 11

difference between Submucosal plexus and Myenteric plexus.

Answer 11

Submucosal plexus- a collection of small clusters of parasympathetic ganglia which supply the mucosal glands and smooth muscle of muscularis mucosae
Myenteric plexus- a collection of larger clusters of parasympathetic ganglia which are found between the two layers of the muscularis propria and supplies surrounding smooth muscle

Question 12

protective mucosa is found where?

Answer 12

oral cavity, pharynx, oesophagus, and anal canal.

Question 13

what is the purpose of stratified squamous epithelium?

Answer 13

Stratified mucosal lining is well suited to sites of potential frictional trauma – such as those associated with mastication, swallowing or defecation

Question 14

which mucosa is only found in the stomach

Answer 14

secretory mucosa

Question 15

secretory mucosa has long tubular gland that produce what?

Answer 15

These glands produce various combinations of acid and digestive enzymes to facilitate digestion and also secrete mucous to protect the mucosa from injury

Question 16

which mucosa is found in the small intestines??

Answer 16

absorptive

Question 17

Villi (V) - are lined by a simple columnar epithelium which is continuous with that of the crypts, what do these crypts do ?

Answer 17

There are crypts that are present in this mucosa and in the duodenum, some of these crypts extend to form Brunners glands in the submucosa – defining characteristic of the duodenum

Question 18

which mucosa is within the large intestines

Answer 18

absorptive/protective

Question 19

This mucosa has straight tubular glands which has specialized cells called?

Answer 19

enterocytes (for water absorption)

Question 20

what lubricate the passage for faeces

Answer 20

mucous-secreting goblet cells