Page 419 - Anatomy and Physiology of Farm Animals, 8th Edition

404 / Anatomy and Physiology of Farm Animals

VetBooks.ir Microvilli
Absorptive
cell
Goblet cell

Villi
Capillary network
Lacteal

Artery
Crypt of Vein
Lieberkuhn Lymph
vessel

Figure 21-5. Intestinal villi and crypts. Source: adapted from Bullock, 1996.

The two primary types of movement by absorptive surface of the epithelial cells.
the small intestine are segmentation and Strong peristaltic contractions of the small
peristalsis. Segmentation movements, intestine in fasting animals or several hours
which occur when food is in the small after a meal propel ingesta down the tract,
intestine, are characterized by alternating presumably to clean the small intestine of
local areas of contraction and relaxation undigested foodstuffs before the next meal.
(Fig. 21‐6). These movements mix the
digesta with intestinal juice and digestive
enzymes and increase the contact between Exocrine Pancreas
digesta and the epithelial surface of the
small intestine. The increased contact The pancreatic exocrine secretions primar-
provides more exposure to enzymes ily consist of a variety of digestive enzymes
associated with epithelial cells and to the and sodium bicarbonate. Pancreatic acinar