Digestive Tract

Digestive tract

General structure of the wall 1.mucosa: – epithelium: – Lamina propria: – Muscularis mucosa: 2.submucosa: 3.Muscularis externa: 4.adventitia:

4sub mucosa

1Epi. 2lamina propria

4esophageal glands

3 muscula ris mucosa

5inner circular M

6 adven titia

5outer longi tudinal M

Esophagus （ HE ）

epitheliu m

Esophag eal gland

Esophagus

Esophagus 1.mucosa:

Epi.: stratified squamous. Non-keratinized ● lamina propria: CT. ● muscularis mucosa: boudles of SMC.longitudinal 2.sbumucosa: esophageal glands, mucous. 3.muscularis: inner circular, outer longitudinal ●

upper1/3: middle:

skeletal M.

mixed.

4.adventitia: fibrosa. Lower1/3: smooth M.

Stomach

fundus

Stomach • mucosa: – – –

Simple columnar Epi.: surface mucous ce Lamina propria: gastric pit, gastric gland Muscularis mucosa: inner circular, outer

longitudinal. • submucosa: LCT.

• muscularis: inner oblique, middle circular,

outer longitudinal.

• Adventitia: serosa.

fundic glands

location ： lamina propria

compositions ： 1.Chief C 2.Parietal C 3.Neck mucous C 4.Endocrine C 5.Stem C

Chief cells

• LM:

Secreto – Lower columnar; ry – basophilic; granule – Nucleus located in the lower parts.

– Secretory granules. • EM:

nucle us

– Gol , Apical of the nucleus; – mit. & rER ,basal part of cytoplasm; – Secretory granules, apical of cytoplasm.

• Function : pepsinogen

rE R

Parietal cells • LM:

microvilli

– C large ， cone-shaped or round. – acidophilic. – Nucleus is round ,centrical. • EM – Introcellular secretory canaliculi & nucleu microvilli. s – Tubulovesicular system. Introcellular – Mit. arecanaliculi abundant. Mitochondr ia • functions: – Hcl & intrinsic factor.

small intestine

duodenum

jejunum

ileum

Central lacteal SMC Cap.

Intestinal gland

1 striated border 1 absorbtive C 2 goblet C

5 stem C 3 Paneth C

4 endocrine C

villi

folds submucosa muscularis adventitia Intestinal villi

microvilli

（ striated border ）

Small intestine • mucosa:

– Epi.: simple columnar, absorbtive C + goblet C. – Lamina propria: small intestinal gland ,central lacteal. – Muscularis mucosa: inner circular, outer longitudinal. villi: the finger-like processes composed of epithelium layer and lamina propria protruding into the lumen .

• submucosa – The duodenal gland, mucosa. Circular folds: mucosa&submucosa protruding into the lumen . Appears as processes. • muscularis: inner circular,outer longitudinal . • adventitia: serosa.

@@@@@small intestinal gland

• Absorbtive C • Goblet C • Endocrine C • Stem C • Paneth C

– LM: the base of gland. arranged in groups of 3-5 cells .

in the apex, coarse acidophilic granules. – EM: protein-secreting cell. – functions: produce lysozyme.

Large intestinal

Epi. Large intestinal gland （ goblet C ）

Lamina propria

Muscularis mucosa Mucosa of large intestine （ HE ）

Large intestine • mucosa: no villi ,no circular folds.

– Simple columnar Epi.: abundant goblet C. – Lamina propria: large intestinal glands, no paneth C. – Muscularis mucosa:

appen dix

•No villi, intestinal gland Is scanty. •Lamina propria: abundant LT. •Serosa

The comparisons between mucosa of variant digestive tract （ 1 ） Small Large esophagus stomac intestine intestine h Gastric pit

surface

Epi.

stratified squamous

Simple columnar

villus Simple columnar Striated border Goblet C

Simple Columnar Goblet C abundant

The comparisons between mucosa of variant digestive tract （ 2 ） esophagu stomach Small Large s intestine intestine Lami No na prop ria

glands Gastric gland

No L nodule

Small Large intestinal intestinal gland gland

No L noduleL nodule

L nodule abundant

lacteal Fundic gland of stomach: chief , parietal, neck mucous , endocrine, stem C. Small intestinal gland: absorbtive, goblet, paneth, endocrine, stem C. Large intestinal gland: absorbtive, goblet, endocrine, stem C.

Key points •Structure characteristics

of variant digestive tract. The similar and the different. •Esp, the variance of tunica mucosa. Such as , the villi and the glands.