The GI Tract Is Supported by the
Peritoneum, and Each of Its Sections
Has Four Layers
The peritoneum (per'-i-to-NE-um) is the membrane that
covers the abdominal organs and lines the abdominal
cavity; it contains large folds that bind the organs to one
another and to the walls of the abdominal cavity. Two of
the major folds are the greater omentum and the mesen-
tery. The
greater o m en tu m
drapes over the intestines like a
fatty apron, and the
m esentery
binds the small intestine to
the abdominal wall. Figure 14.2 shows the relationship
between the peritoneum and the organs of the digestive
system.
Each section of the GI tract has four layers. From the
inside out, they are the mucosa, submucosa, muscularis,
T h e p e r i t o n e u m a n d t h e f o u r la y e r s o f t h e g a s t r o i n t e s t i n a l t r a c t •
F ig u r e 1 4 . 2
a.
The peritoneum
Liver
Stomach
Transverse colon
Urinary bladder
G reater
omentum is a “fatty apron” that
drapes over the intestines. It has large
amounts of adipose tissue and lymph
nodes that contribute macrophages and
plasma cells to fight infections.
Anterior
view
Greater omentum
(reflected upward)
Descending colon
Ileum (pulled laterally)
Sigmoid colon
Urinary bladder
M esentery is part of the peritoneum that
binds the small intestine to the abdominal
wall.
Anterior
view
(greater omentum
lifted and small intestine pulled
laterally
to
right side)
402 CHAPTER 14
The Digestive System, Nutrition, and Metabolism
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