Small Intestine

1) Parts of the small intestine

Consists of the duodenum, jejunum, and ileum

2) Small intestine wall

A. Lined with villi that greatly increase surface area and aid in absorption and mixing.

B. Intestinal Glands are located between the villi.

3) Small intestine secretions

A. Secretions include mucous and digestive enzymes.

B. Digestive enzymes embedded in the surface of microvilli split molecules of sugars, proteins, and fats to more simple forms.

4) regulation of small intestine secretions

Stimulated by gastric juice, chyme, and reflexes stimulated by dissension of the small intestinal wall.

5) absorption in small intestine

A. Blood capillaries in the villi absorb monosaccharides and amino acids.

B. They also absorb water and electrolytes

C. Fat molecules with longer chains of carbon atoms enter the lacteals of the villi.

D. Fatty acids with shorter carbon chains enter the blood capillaries of the villi.

6) Movements of the small intestines

A. Include mixing by segmentation and peristalsis

B. Ileocecal sphincter controls movement of intestinal contents from small to large intestine.