The Digestive System Pt 1

The purpose of the digestive system is to process food _____ and _____ into small molecules for _____ across the epithelial lining

mechanically, chemically, apsorption

Digestive tract consists of:

A: Oral cavity

B: Pharynx

C: Esophagus

D: Stomach

E: Small intestine

F: Large intestine

Accessory Organs

G: Salivary glands

H: Liver

I: Gall bladder

J: Pancreas

The ____ is the largest internal organ

liver

A-D

A: Mucosa

B: Submucosa

C: Muscularis externa

D: Serosa

Mucosa

• Epithelium varies

  • Lamina propria: areolar CT with mucosal glands, BVs, capillary beds, Ns, Ls

Submucosa

• Dense irregular CT

• BVs, Ls (submucosal glands)

• Submucosal (Meissner plexus)

Muscularis externa

• Circular muscle layer

• Myenteric plexus

• Longitudinal muscle layer

• Pacesetter cells & gap junctions; peristalsis vs. segmentation

Serosa = _____ aka ________ or _____

Serous membrane, peritoneum, adventitia

Digestive tract is more active with ____ activity

PNS

The ______ helps to move food down the digestive tract

muscularis externa

____ in the mucosa sometimes absorb fat

Ls

Vessels in the submucosa are much ____

larger

Top to bottom

• Plica (increase surface area)

• Muscularis mucosa

• Mucosa

• Submucosa

  • Circular muscle layer

• Longitudinal muscle layer

• Serosa

______ and ______ are part of the muscularis externa

circular muscle layer, longitudinal muscle layer

The esophagus is a ______, ___ long and ___ in diameter

hollow tube, 25cm, 2cm

Esophagus passes through the _______ via the __________

diaphragm, esophageal hiatus

Esophagus mucosa histology

• Stratified squamous epithelium with Langerhans cells

• Lamina propria containing esophageal cardiac cells

Role of langerhans cells

Neutralize pathogens

Role of esophageal cardiac glands

Secrete mucous and bicarbonate; protects digestive tract from acids

Esophagus submucosa histology

Submucosal glands, submucosal vascular plexus, lymph nodules

Submucosal vascular plexus activated by the ____

PNS

Esophagus muscularis externa histology

• Changes from striated to smooth muscle; involuntary throughout

• Upper/lower esophageal sphincters ill-defined

Esophagus adventitia histology

Anchors esophagus to adjacent structures in post mediastinum

• Muscularis mucosae

• Mucosa

• Submucosa

• Muscularis externa

• Adventitia

• Stratified squamous epithelium

• Lamina propria

• Muscularis mucosae