1. Break down large molecules into smaller one for easy absorption.

2. Absorb water, vitamins and minerals from food.

3. To provide a barrier for rest of the body from the contents of the lumen.

1. Mucosa (epithelial lining, lamina propria and muscularis mucosae)

2. Submucosa

3. Muscularis Externa

4. Serosa

1. Epithilial lining - StratSE to Simple Cub. Epithelium.

2. Lamina propria - Areolar CT, very vascular, lymphatics, smooth muscle, lymph tissue and sometimes glands.

3. Muscularis Mucosae - usually inner circular and outer longitudinal layers of smooth muscle.

Proximal (mouth) - Striated

Middle - Striated and Smooth

Distal - Smooth (this is where some serosa is found, after passing through diaphram)

1. Secretes hormones (neuroendocrine cells)

2. Continues breakdown of carbs

3. introduce acidic fluid to food

4. Process food into chyme with muscular action

1. Cardia

2. Fundus

3. Body

4. Pylorus

-Simple Colum. Ep. forms gastric pits

-Barned tubular glands empty into pits

-All Ep. cells secrete mucous to protect from acid

-Transition zone from esophagus to stomach.

-Cariac glands in lamina propria secrete mucous, lysozyme and some HCL

Where are gastric glands located?

In fundus and body.

Empty into shallow gastric pits and contain many cell types.

-Rare

-Actively dividing

-Can replace surface or pit cells  or differentiate into mucous neck, parietal, chief or enteroendocrine

-Irregually shaped and secrete mucous

-Trap bicarbonate to neutrilize pH near epithelium

-Stimulated by vagus nerve, stomach distention and HCL

-Mainly in upper portion of gastric gland

-Round/triangular with centrally placed nucleus

-Secrete HCL, KCL and gastric intrinsic factor (B12 absorbtion)

-Stimulated by histamine and gastrin

-Near base of gastric glands

-Basophilic, granules contain Pepsinogen (pepsin ->protein digestion)

- Secrete lipase for fat

-Near base of gastric gland

-part of Diffuse Neuroendocrine System DNES

-hormones released:

1. regulate water and electrolyte met. and enzyme secretion

2. regulat GI motility and mucosal growth

3. stimulate release of other hormones

-Many DEEP gastric pits that empy into simple tubular glands

-Contain mucous, gastrin and D cells

-Glands secrete lysozyme

-Type of enteroendocrine cell

-release somatostatin whihc inhibits gastrin release

3:

1. External longitudinal

2. Middle circular

3. Inner oblique

Middle layer becomes thickened to form pyloric sphincter

-Most food undergoes final digestion

-Nutrients are absorbed

-Hormones are secreted

-Have very long villi for absorbtion

1. Duodenum

2. Jejunum

3. Ileum

Jejunum.

Known as Plicae Circulares

1. Mucosa

2. Submucosa (separated from mucosa by the muscularis mucosa)

3. Muscularis Externa (2 layers)

4. Serosa (covered by mesothelium of the visceral peritoneum)

-Tall columnar cells with oval nucleus near base

-Brush border at apex

-Border consists of microvilli and glycocalyx

-Nutrient absorbtion as well as enzyme breakdown of carbs and proteins occurrs here

(lipids are digested via pancreatic lipase and bile)

-Stuck between absorptive cells

-Increase in number toward distal end of intestine

-Secrete mucous

-Pyramid shaped exocrine cells located in basal area of intestinal glands

-Secrete lysozyme,

tumor necrosis factor (promotes inflammation)

and  defensins (increase perm. of bacteria and parasites)

-Special epithelial cell

-Holds macropahges and lymphocytes, keeps them readily available

-Can bring antigens to them for destruction

1. Provide a pool of cells tomigrate to villi and replace lost cells

2. Secrete mucous

3. Produce alkaline fluid to neutralize stomach acid

1. Secretin - enhances insulin and pancreatic bicarbonate secretion

2. Cholecystokinin - slows down gastric emptying, stimulate bile and pancreatic enzyme secretion

-Comprised of Meissner's plexus within the submucosa

-Aurbach's plexus between the 2 smooth muscle layers

-These integrate info about intestinal contents and degree of distention in the wall

-Parasympatheic nerves that stimulate activity

-Sympathetic nerves that depress activity

-Submucosal Brunner's glands (coiled tubuloacinar glands that secrete alakiline mucous, empy into crypts)

 -Short leaf-like villi

-Occasional Paneth cells at crypt base, enteroendocrine cells in villi

-Long finger-like villi, prominet lacteals

-NO brunner's glands

-Possible peyer's patches

-Crypts have paneth cells

-Lots of Peyer's patches (all immune tissue)

-Villi finger-like but short

-Paneth cells in crypt base

-Lymphoid follicle within the mucosa and submucosa of parts of the small intestine

-Comprise most of the gut associated lymph tissue GALT

1. Dome - between peyer's patch and suface epithelium. Contains B lymphocytes, macropages and plasma cells

2. Germinal center - contains B lymphocytes expressin IgA, CD4+ T lymphocytes, and antigen presenting cells

1. Cecum (with appendix)

2. Acending colon

3. Transverse colon

4. Descening colon

5. Sigmoid colon

6. Rectum

1. Absorb water, minerals, sodium, and vitamins

2. Secrete mucous

3. Form feces

False. The large intestine has no folds or villi (except in the rectum). There are numerous glands of Leiberkuhn.

1. Absorptive

2. Goblet

3. Stem

4. Enteroendocrine

-Stems from the cecum

-Has some folds

-Very large amounts of lymphiod tissue (possibly important early in life)