Histology Of GIT

Question 1

What are the accessory structures of the digestive system?

Answer 1

Tongue and Teeth

Question 2

What are the accessory organs of the digestive system?

Answer 2

Salivary glands,liver and pancreas.

Question 3

Describe the Structure of the salivary glands

Answer 3

Covered by capsule made of connective tissue.
Separated into lobules.
Lobules separated from one another by septa.
Septa contain blood vessels

Question 4

What are the 3 Types of acini?

Answer 4

Mucous acini
Serous Acini
Mixed acini

Question 5

Describe mucous acinus

Answer 5

Oval shaped
Large lumen
Lined by columnar acinar cells
Cells have flat nucleus situated on the basement membrane
CELLS ARE CLEAR AND TRANSPARENT
Cells secrete mucinogen

Question 6

Describe serous acini

Answer 6

Spherical in shape.
Small lumen
Round nucleus NEAR the basement membrane
Secretes alpha amylase.
Cells are PINK

Question 7

Describe mixed acini

Answer 7

Mainly mucous acini
Crescent shaped serous cells
Caps of serous cells are called serous demilunes or crescents of Gianuzzi

Question 8

What type of gland has serous acini?

Answer 8

Parotid Salivary salivary gland is a serous gland

Question 9

What type of gland has mucous acini?

Answer 9

Sublingual salivary gland is mucous acini

Question 10

What gland has mixed acini?

Answer 10

The submandibular gland has mixed acini

Question 11

What are the two surfaces of the tongue?

Answer 11

Dorsal surface and the ventral surface.

Question 12

What is the tongue covered by an what are its constituent parts

Answer 12

The tongue is covered by a mucous membrane
The mucous membrane consists of the outer epithelium and inner laminate Prophase.

The is also skeletal muscle inside the tongue.

Question 13

Describe the outer epithelium layer

Answer 13

It is of stratified squamous non Keratinized
However it is keratinized over the papillae.

Question 14

Describe the lamina Propia of the mucous membrane

Answer 14

It contains connective tissue,blood vessels and serous and mucous glands.

Question 15

Describe filiform papillae

Answer 15

Small conical projections
Found on the dorsum anterior 2/3 of the tongue
NO taste buds

Question 16

Describe fungi form papillae

Answer 16

Rounded top and narrow base.
Has taste buds
Present at the apex and lateral margins of anterior 2/3 of the tongue

Question 17

Describe circum vallate papillae

Answer 17

Largest
Situated in a depression
Taste buds on the lateral wall
Surrounded by circular sulcus
Sulcus receives opening of serous glads.
Secretions front these glands
Mucous and serous acini present

Question 18

Order of tissues of the GIT

Answer 18

Lumen
Mucousa- 3 layers—->epithelium,lamina propia,muscularis mucousa
Submucousa- connective tissues,glands,blood vessels and nerves
Muscularis Externa - smooth muscle layers(2-3 layers)
Serous- CT,supports and binds organs to one another
Adventiva- esophagus and most of duodenum

Question 19

Describe the general mucousa structure

Answer 19

3 layers
Epithelium- simple columnar
Lamina Propia- loose areolar CT,LV,BV,LN,LV
Muscularis mucosa- ICL,OLL of smooth muscle
Outermost covering- peritoneum made of CT and a layer of simple squamous cells.

Question 20

Describe he general submucosa layer.

Answer 20

Made of irregular fibroelastic connective tissue with elastic collagen fibers
No glands except in esophagus and duodenum.
Meissners complex here

Question 21

Describe the general structure of the muscularis externa

Answer 21

Inner Cicular Layer of Muscle-ICL
Outer Longitudinal Layer - OLL
Auerbach/Myenteric Complex

Question 22

Describe the serousa layer of the GIT

Answer 22

Outer most layer formed by visceral peritoneum(simple squamous layer)
If the organ is retroperitoneal serosa is replaced by adventivia.

Question 23

Describe the Histology of the esophagus

Answer 23

Lowest part of esophagus lined by simple columnar epithelium.
Esophageal glands found in submucosa lined by simple columnar epithelium,secrete mucus.
Muscularis externa in upper esophagus is made skeletal muscle fibers
Middle part made of both skeletal and smooth muscle
Lower esophagus made of smooth muscle fibers

Question 24

Histology of the Stomach

Answer 24

Most dilated part of the GIT
4 parts- cardia,fundus,body,pyloric part.
Gastric ruggae,folds of the mucosa, present only an empty stomach

Mucosa
1)Epithelium-simple columnar
2)Lamina Propia- loose irregular connective tissue with BV
- contains gastric pits,inner 1/3 of LP
- gastric glands,deeper 2/3 of LP
Submucousa- 2 layers,ICL,OLL.

Muscularis externa- IOL,MCL,OLL

Serosa- visceral peritonaeum,layer of simple squamous cells

Question 25

What are the three types of cells found in the gastric pits

Answer 25

Mucous neck cells- found at head of the gland,small blue Parietal/Oxyntic Cells- rounded,pink, located in the side walls of the glands,produce HCL. Peptic/Chief/Zymogenic cells- take basic stain,blue,located at basal part of the gland,produce gastric enzyme pepsin Neuroendocrine cells- secrete serotonin and gastrin

Question 26

Describe the Pyloric part of the stomach

Answer 26

Epithelium is simple columnar type. Gastric pits and glands in LP(Pyloric Glands) Gastric pits are DEEP, inner2/3 Gastric glands outer 1/3

Question 27

Describe the histology of The small intestine.

Answer 27

Made of 3 parts. Duodenum,jejunum,ileum. Mucosa- forms tall projections called villi,core of villi is formed by CT,BV,LV of the LP -Epithelium- simple columnar epithelium(enterocytes) and some goblet cells. -Lamina Propia- CT,BV,LV,glands called crypts of lieberkuhn.crypts are lined by simple columnar cells with microvilli(enterocytes) which are absorptive in function Other cells lining the crypts- goblet cells that produce mucin,paneth cells are defensive in function,neuroendrocrine cells that produce locally acting hormones. -also contains solitary lymphoid follicles called Peyers Patches(lamin propia of ileum) Muscularis Mucosa- ICL,OLL of SM fibers. Some of the fibers extend into the core of the villus Submucosa- CT,BV,LV,NF. Burners glands in the duodenum+Peyers patches in the ileum. Muscularis Externa- OLL,ICL of SM fibers Serosa- visceral peritoneum,single layer of squamous cells.

Question 28

Describe the histology of the colon.

Answer 28

Plenty goblet cells and few simple columnar cells in mucosa,crypts of lieberkuhn present(in LP too)

Question 29

Describe the Histology of the appendix

Answer 29

Simple columnar cells with lots of goblet cells in mucosa. LP contains aggregation of lymphocytes extend into into submucosa