General Structures - Hollow Organs

How many primary layers do hollow organs have?

4

What are the primary layers of hollow organs?

Mucosa

Submucosa

Muscularis externa

Serosa/Adventitia

What is the innermost layer of GI tract?

Mucosa

What is the outermost layer?

Serosa/Adventitia

How many sublayers does mucosa have?

3

List sublayers of the mucosa: Innermost to outermost

Epithelium

Lamina propria

Muscularis mucosae

What does the lamina propria contain?

Blood vessels

Nerves

Immune cells

Lymphatics

Loose connective tissue

MALT

What does muscularis mucosae contain?

(Thin) Smooth muscle

What is the Submucosa?

Layer of dense irregular connective tissue that supports the mucosa.

What does submucosa contain?

Blood vessels

Nerves

Lymphatics

Glands

Meissner’s plexus

Muscularis externa contains:

Mostly smooth muscle

Auerbach’s plexus

What is the Serosa and its contents?

Connective tissue + Mesothelium

Outermost layer of hollow organ

Mesothelium?

Layer of simple squamous epithelium that covers/lines the connective tissue of hollow organ

What is the function of the serosa?

Lubrication: reduce friction

What is the Adventitia?

Outer layer of connective tissue surrounding hollow organs that blends in with its surroundings.

Function of adventitia?

Anchors hollow organs to surroundings structures

Functions of epithelium include:

Absorption

Secretion

Protection

Epithelium features:

Avascular

Rests on/attached to basement membrane

List hollow organs:

Stomach

Small/ Large intestine

Esophagus
Bladder

Trachea/Bronchi

Uterus

Ureters

Oviducts

Urethra

Renal pelvis

Larynx

What is MALT:

Mucosa associated lymphoid tissue

MALT locations:

GI tract

Respiratory tract

Urogenital tract

MALT contents:

Macrophages

Plasma cells

Dentric cells

Lymphocytes

Muscularis externa function:

Peristalsis

Mobility layer, to control movement of contents