General histology of GIT Flashcards
what is the function of gastrointestinal tract
to break down food for absorption into the body.
Four layers of GIT
Mucosa
Submucosa
Muscularis propria
Adventitia
Where does GIT start and end
from mouth to anus
components of mucosa
Epithelium
Supporting Lamina propria
Smooth muscle layer – muscularis mucosae
what does these components do?
These components produces local movement and folding of the mucosa.
List and describe the four points of mucosa.
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
submucosa is a layer of loose connective tissue, it has … and supports….?
it supports mucosa and has large vessels, nerves and lymphatics
muscularis propria has two layers arranged as ?
inner circular and outer longitudinal which contribute to peristaltic contraction.
adventitia is often referred as ? and why?( outer layer of loose connective tissue)
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.
Contraction of smooth muscle is initiated by pacemaker cells known as ?
interstitial cells of Cajal
difference between Submucosal plexus and Myenteric plexus.
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
protective mucosa is found where?
oral cavity, pharynx, oesophagus, and anal canal.
what is the purpose of stratified squamous epithelium?
Stratified mucosal lining is well suited to sites of potential frictional trauma – such as those associated with mastication, swallowing or defecation
which mucosa is only found in the stomach
secretory mucosa
secretory mucosa has long tubular gland that produce what?
These glands produce various combinations of acid and digestive enzymes to facilitate digestion and also secrete mucous to protect the mucosa from injury
which mucosa is found in the small intestines??
absorptive
Villi (V) - are lined by a simple columnar epithelium which is continuous with that of the crypts, what do these crypts do ?
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
which mucosa is within the large intestines
absorptive/protective
This mucosa has straight tubular glands which has specialized cells called?
enterocytes (for water absorption)
what lubricate the passage for faeces
mucous-secreting goblet cells
