Stomach

The stomach of the dog and cat is described as being sijnplc and digestion is said to be monogastric. The functions of Ihestomach are:

1. To act as a reservoir for Rxxl - wild carnivores

(particularly dogs) may only cat every 3-4 days and then rest while food slowly digests

2.

3. To begin the proccssof protein digestion.

The stomach is a C-shaped sac-like organ lying on the left side of the cranial abdomen. Fare know^rn as succus entericus

Crypts of Leiberkuhn in the jejunum and ileum.

A number of enzymes are present, many of which are also produced by the pancreas:

⅛* Maltase converts maltose to glucose

Sucrose converts sucrose to glucose and fructose Lactase converts lactose to glucose and galactose Enlcrokinasf converts trypsinogen to trypsin Aminopeptidase converts peptides to amino acids β Lipase converts fats to fatty acids and glycerol.

The result of the digestive process is that the basic constituents of food are converted into small molecules that can now be absorbed.

Protein

(polypeptides)-------- ^co*^w*^rt*^dl°—> Amino acids

Carbohydrates

(polysaccharides —^tt***^rw*^l°—> Glucose and other and disaccharides) simple sugars

(monosaccharides)

Fats----------------------- com⅝rtcdto—_> Fatty acid and glycerol

(monoglycerides)

Absorption

The main site for absorption is the villi of the small intestine. The efficiency of the absorptive process is increased by:

The long length of the small intestine

The internal surface area (increased by the presence of the villi)

Each villus is well supplied w ith blood capillaries and Iacteals.

During absorption amino acids and simple sugars are absorbed by the bkκκl capillaries and are carried by the hepatic portal vein to the liver. Fatty acids and glycerol are absorbed by the Iacleals. They form a fatty milky liquid know n as chyle, which is carried to the cisterna chyli, lying in the dorsal abdomen (see Ch. 7. Fig. 7.7). Here it is mixed with lymph and carried to the heart by the thoracic duct, w here it joins the blood circulation.