Digestive System Anatomy

Alimentary Canal

-Epithelial lining

-Mucosa

-Submucosa: gland

-Muscularis: circular & longitudinal

-Serosa: visceral peritoneum

Esophagus

Elastic folds, stretchy, muscular

-Mucosa

-Submucosa(CT)

-Muscularis: circular & longitudinal

-ADVENTITIA (CT)

No digestion or absorption, only peristalsis

(Stratified squamous epithelial lining)

Cardioesophageal junction

Esophageal glands lubricate

Stomach

-Cardia: lubricates

-Fundus: stretches/expands

-Body: churns

*Oblique layer is unique to stomach*-pushes food

-Pylorus: digests

-Rugae: stretch

-Pyloric sphincter→ duodenum

-*Forked Intestinal Crypts*

-Gastric pits in mucosa

(simple columnar epi)

Gastric Pit

Chief cells→ pepsin→ break down proteins (purple nucleus)

Parietal cells→ Hydrochloric acid (HCL)→ digests, lowers pH to kill bacteria & Intrinsic Factor→ Vit B12 absorption (pink nucleus)

Enteroendocrine→ gastrin→ stimulates secretions

(found in stomach mucosa)

Duodenum

-most absorption occurs here

-Brunner’s glands: secrete alkaline mucus (neutralizes chyme’s pH)

- Papilla

-Plica (circular folds), villi, & microvilli/brushborder

-Point where pancreatic enzymes and bile are released

-lacteals absorb fat

(simple columnar)

Jejunum

-long fingerlike villi

-well developed plicae (circular bumps)

-contains intestinal crypts

-Paneth cells: produces antimicrobial proteins (at base of crypts)

Ileum

-Peyer’s patches: unencapsulated (no fat/triglyceride chain) lymph nodes, kill bacteria, have memory

Ileocecal Valve

sphincter between SI & LI

Colon/Large Intestine

-Haustra: pocket-like sac lining, allowing for expansion

-Intestinal crypts

-Goblet cells (white dots)

-Enterocytes: absorb water

(simple columnar)

GIT Model

-Esophagus

-Stomach

-SI

-LI

Mesentery

formed from visceral peritoneum

Omenta

formed from parietal peritoneum

Incisor

8, cut

Canine

4, pierce & tear

Premolar

8, grind

Molar

12, grind

Filiform

front, crush food against hard palate

Fungiform

middle, manipulate food for mastication (pushing food between teeth while chewing)

Circumvallate

back, positions for swallowing

Liver

-Lobules

-Hepatocyte

-Central vein

-Hepatic sinusoid

-Hepatic portal vein

-Hepatic artery

Pancreas

-Acinar cells: (exocrine) produce digestive enzymes, found outside of islets