Lecture 5: Histology of the Esophagus, Stomach, and Intestines | Quizlet

Muscularis Mucsoa

- thin layer of smooth muscle

- maintains constant state of gentle agitation

- helps expel secretions

Mucosa

1

Submucosa

2

Muscularis Propria (Muscularis Externa)

3

Serosa

4

Lamina Propria

-in mucosa of GI tract

-loose irregular connective tissue (CT)

- may contain immune cells (diffuse lymphoid tissue (MALT))

Non-keratinized Stratified Squamous

or

Simple Columnar

type of epithelium in the mucosa of the GI tract

Submucosa

• loose CT (collagen, adipose)

• contains nerves, lymphatics, vasculature, glands

- Meissner's plexus

Muscularis Propria (Muscularis Externa)

• typically 2 layers of smooth muscle (inner-circular; outer-longitudinal)

• peristalsis

• inner layer enlarged to form sphincters

• contains myenteric (Auerbach's) plexus

Adventitia

-is loose CT that blends with surrounding structures

- exs. retroperitoneal organs, esophagus

• contains large nerves, lymphatics, vasculature

Serosa

• contains large nerves, lymphatics, vasculature

-is loose CT with simple squamous epithelium (mesothelium)

- ex. intraperitoneal organ

Mucsoa

1

Epithelium

2

Muscularis Mucosa

3

Lamina Propria

4

Submucosa

5

Muscularis Propria (Externa)

6

Submucosa (Meissner) Plexus

Tiny parasympathetic ganglia PG are scattered throughout the submucosa, forming the _________________________ from which postganglionic fibers supply the muscularis

Myenteric (Auerbach) Plexus

Between the layers of MUSCULARIS EXTERNA (MP), there are clumps of pale-stained parasympathetic ganglion cells of the ___________________________

Non-Keratinized Stratified Squamous

epithelium of the esophagus

-striated (proximal 1/3)

-smooth (distal 1/3)

-mixed (middle 1/3)

Types of muscle in the Muscularis Propria (Externa) of the esophagus?

Cardia

-region of the stomach

-narrow

-mucus production primarily

Fundus and Body

-region of the stomach

-releases acid to form gastric juice

Pylorus

-region of the stomach

-mucus production primarily

Simple Columnar

type of epithelium of the stomach

Gastric Pits

invaginations of the stomach that open into the lumen

Surface Mucous Cells

-line the lumen and gastric pits of the stomach

-hihgly viscous secretion

-protects against abrasion form food and self corrosion from stomach acid

Stem Cells

-located in the isthmus between gastric puts and gastric glands

Mucous Neck Cells

-located in the isthmus/neck of stomach

-apical granules and round nuclei

-acidic mucin

Parietal Cells

-large, often pyramidal-shaped

-located deep within the gland

-eosinophilic

-invagination of the PM on apical side that forms an intracellular canaliculus with many microvilli that produce HCl and secretes intrinsic factor

Chief (Zymogenic) Cells

-located deep within the gastric gland

-secrete pepsinogen and gastric lipase

Enteroendocrine (G) Cells

-scattered in stomach

-secrete hormones: 5-HT, histamine, gastrin, somatostatin, etc.

Gastric Pit

Gastric Gland:

1

Gastric Glands

2

Muscularis Mucosa

Gastric Gland:

3

Submucosa

connective tissue containing large blood and lymphatic vessels and many lymphoid and mast cells

Muscularis Propria (Externa)

3 poorly defined smooth muscle layers - oblique (inner), circular (middle), longitudinal (outer)

Pyloric Sphincter

the middle layer fo the Muscularis Propria (Externa) thickens greatly to form the ___________________

Gastric Pits

2

Gastric Surface Mucous Cells

Parietal Cells

Parietal Cells

1

Chief (Zymogenic) Cells

2

Surface Mucous Cells

1

Mucous Neck Cells

2

Parietal Cells

3

Chief (Zymogenic) Cells

4

Enteroendocrine (G) Cells

5

Enteroendocrine (G) Cells

Enteroendocrine (G) Cells

small pyramidal cells with clear cytoplasm found interspersed among chief cells

Cardiac Gland

Which type of Gastric Gland:

-primarily secrete mucus

-fewer in number and more shallow in the stomach wall

Fundic Gland

Which type of Gastric Gland:

-simple, straight, with two or more opening into a single duct

-mainly secrete HCl

-release intrinsic factor

Pyloric Glands

Which type of Gastric Gland:

-secrete gastrin produced by G cells

Duodenum

-receives acidic chyme form the sotmach so it must neutralize gastric acid and pepsin as well as carry out further digestion

Jejunum

-the longest section of SI

-functions in digestion and absorption

Ileum

-last section of small intestines

-functions in absorption

Plicae Circularis

-circular folds

- most prominent in jejunum

- formed of mucosa and submucosa

- permanent (unlike stomach rugae)

Small Intestines

Brush Border

small intestines

Intestinal Crypts

-formed by epithelia of the villi that extend down into the lamina propria

-stem and paneth cells located here

Enterocytes

simple columnar; absorptive cells

Goblet

secrete mucins; lubricate (protection)

Stem Cells

mitotic; replenish epithelial cells further up the villi (right image)

Paneth Cells

eosinophilic; secrete enzymes and defensins to protect against microbes; provide innate immunity

Brunner's Glands

-in submucosa

-mucigen filled clear cytoplasm and basally located nucleus

-secretes a thin, alkaline mucous to neutralize chyme

-produces lysozyme and epitdermal growth factor

Peyer's Patches

- location: mucosa, submucosa

- abundant

- lymphoid nodules

Peyer's Patches

ileum

Dudoenum

Brunners glands are only present where?

Duodenum

Villous length is longest in the ____________________

Ileum

Villous length is shortest in the __________________

Plica Circulares

- absent in proximal duodenum and distal ileum

- pronounced in jejunum and proximal ileum

Ileum

Lymphoid tissue is more prominent where?

Ileum

there are more goblet cells in the _____________

Lymphatic Nidule

1

Circular Layer of the Muscularis Externa

2

Longitudinal Layer of the Muscularis Externa

3

Muscularis Mucosa

4

Stratified Squamous

type of epithelium in the anus

White Line of Hilton

is situated between the external and internal anal sphincters.

Vermiform Appendix

Features:

• cell types: enterocyte, goblet, enteroendocrine, stem cells, Paneth cells

• nodular lymphoids in lamina propria and submucosa; lymphoid follicles

Gastroesophageal Junction

regional change from stratified squamous to gastric secretory

Gastroduodenal Junction

regional change from gastric secretory to intestinal absorptive/villous

Ileocecal Junction

regional change from intestinal absorptive/villous to colorectal absorptive/protective

Rectoanal Junction

regional change to colorectal absorptive/protective to stratified squamous

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