The small intestine is responsible for most digestion and absorption of nutrients. It is divided into three parts - the duodenum, jejunum, and ileum. The duodenum contains Brunner's glands which secrete mucus to protect the lining and help regulate pH. It connects to the bile ducts and pancreas. The jejunum and ileum further digest food and absorb nutrients through fingerlike villi before waste passes to the large intestine.

2.  part of the gastrointestinal tract
following the stomach and followed
by the large intestine
 where much of the digestion and
absorption of food takes place
 primary function is to absorb the
nutrients and minerals found in food

4.  average length of the small intestine
 in an adult male
- 22 feet 6 inches (6.9 m)
 in the adult female
- 23 feet 4 inches (7.1 m)

5. The small intestine is where most
digestion takes place.
It is structurally divided into three
parts:
› duodenum
› jejunum
› ileum

7.  major distinguishing feature is the presence of duodenal
(Brunner's) glands in the submucosa
 where most of the breakdown of food in the small
intestines occurs.
 mucous cells of these glands produce an alkaline secretion
 protects the duodenal lining from the acidity of the chyme
 raises the luminal pH to the optimum level for pancreatic
enzyme activity
 also the point of entry for the bile and pancreatic ducts
 exhibits fingerlike or leaflike villi
 few goblet cells

8. The duodenum consists of four parts, with
the first three forming a "C" shape.
› first or superior part begins at the pylors, passing
laterally for a short distance before curving into the
superior duodenal flexure
› second or descending part passes from the superior
into the inferior duodenal flexure
› third or inferior part passes from the inferior
flexure, crossing the major artery and the major
vein and also the spinal column
› forth or ascending part passes over the aorta, and
curves past the pancreas to the duodenojejunal
flexure

9. Duodenum-Brunner's Glands

10.  has long leaflike vilii
 many plicae circulares
 an intermediate number of goblet cells
The key to its identification is that although it
has villi (part of the small intestine), it
doesn’t contain Brunner's glands or Peyer's
patches.

12.  final and longest section of the small intestine
 jejunum and ileum both suspended by a double
layer of peritoneum that allows these parts to
move more freely within the abdomen
 responsible for the final stages of protein and
carbohydrate digestion
 has fewer villi, which are short and broad-
tipped (clublike)
 relatively abundant goblet cells

13. Goblet Cells

14.  colon cancer
 Small bowel bacterial overgrowth syndrome
 Paralytic ileus
 Maropthisis
 Crohn's disease
 Celiac disease
 Carcinoid
 Meckel's Diverticulum
 Gastric dumping syndrome
 Infectious diseases
 Mesenteric ischemia
 Intussusception