Digestive System

    Most primates are nearly or exclusively herbivores, but their digestive tract does

not show the high degree of morphological specialization seen in many other

herbivores.  The digestive system of Chimpanzees and mammals is made of the

alimentary canal and the different accessory glands that hide digestive fluids in the

canal and through the ducts. The digestive track has a wall with four layers. First is

the lumen, the cavity, is lined by a mucous membrane, the mucosa.  Then comes

the layer of connective tissue, which is followed by the smooth muscle. Lastly

comes the outer most layer which is a sheath of connective tissue that is attached to

the membrane of the body cavity. There are schincters that regulate the passage of

the food between the chambers of the canal.

        Starting off of the digestive system is with the oral cavity.  The sensation of food

in the oral cavity sends a reflex that triggers the salivary glands that send saliva

through ducts to the oral cavity.  Saliva can appear in the oral cavity before food is

there because it is in anticipation. Next, the pharynx is in the throat, intersecting

the windpipe and esophagus. Once people swallow, the top of the trachea, which is

the windpipe, is closed off by the cartilaginous flap called the epiglottis.  This action

that is performed prevents food or liquid from entering the windpipe.  The

esophagus then moves the food from the pharynx down to the stomach. At the top

of the esphagus there are muscles, and those muscles are striated. So, the start of

actually swallowing is voluntary, yet involuntary waves of contractions happen

uncontrollably by the smooth muscles. The saliva continues to hydrolyze starch

and glycogen as the food goes through the esophagus.

        Although some of digestion occurs in the oral cavity and stomach, the majority

of it takes place in the small intestine.  The pancreas, liver, and gallbladder are also

part of the digestion process. The pancreas is what makes several hydrolytic

enzymes and an alkaline solution. The liver has a variety of different roles, and one

of them is to produce bile.  The small intestine contains the duodenum in the first

twenty-five centimeters. This is where the digestive fluid from the pancreas, liver,

gallbladder, and gland cell from the wall of the intestine mix with the acid chyme

that seeps from the stomach.  The large intestine or colon is attached to the small

intestine and also plays a role in digestion. The major function of the colon is to

reabsorb water that has entered the alimentary canal. The colon finishes up the

work by reclaiming the water that has stayed in the lumen. The final phase of the

digestive system is when the feces reach the terminal part of the colon called the

rectum. This is where the feces are stored until they are eliminated.