THE DIGESTIVE SYSTEM

Digestion is the process of breaking complex foods down into soluble, absorbable materials then absorbing or storing the material and eliminating the waste material from the body.

PROCESS OF DIGESTION

MOUTH

1)        Intake of food.

2)     Chewing reduces the size of food while at the same time the glands of the mouth mix in mucin and saliva and then pushes it through the cardiac orifice.

STOMACH

1)          The stomach churns the food while mixing it with gastric juices and then changes it into chime.

2)         The muscles of the stomach constrict and then relax which forces the food into the small intestine (duodenum - 10 inches long) by way of the pyloric sphincter.

SMALL INTESTINES

1)      The small intestines continues to churns and push the food along while it also mixes it with digestive juices.  The food remains in the small intestine several hours and it is here that many of the digestive food products are further churned and then absorbed by the blood and lymph system.  The food now leaves the small intestines jejunum (9.5 feet long) and ileum (12.5 feet long) through the ileocecal valve.

2)     Digested amino acids, fats, mineral salts, simple sugar, vitamins and water are absorbed by the blood and thus carried by way of the portal vein to the liver, hepatic vein, inferior vena cava, lungs, heart and then to the cells of the body by way of the red blood cells.             

LARGE INTESTINES

1)           Muscle contraction(s) and relaxation continues in the large intestines at a much slower rate which causes the food residues mixed with bacteria to stay in the large intestine for twenty four (24) hours or more.  Muscle contraction(s) and relaxation force the remaining material through the sigmoid colon and rectum.

 2)         The main functions of the large intestines are to absorb water and excrete waste material from the body. 

ACCESSORY GLANDS OF THE DIGESTIVE SYSTEM

SALIVARY GLANDS

Made up of parotid, submandibular and sublingual glands which produce most of the two (2) to three (3) pints of saliva secreted daily.  Saliva is ninety eight percent (98%) water plus enzymes, mineral salts, mucin and organic        compounds. 

Enzymes convert starches to maltose and maltose to dextrose.

Mineral salts are seen in tartar deposits on the teeth.

Mucin binds food particles together into a bolus for swallowing and ubricates the buccal cavity.

LIVER

Largest gland of the body which is ten (10) inches wide and weighs three (3) to four (4) pounds.  It has four (4) lobes named right, quadrate, caudate and left which are in turn separated by fissures through one of which pass the hepatic artery, portal vein and common bile duct.  The common bile duct formed by the common hepatic duct and the cystic duct leads into the duodenum below the pyloric opening of the stomach.

Some Of The Functions Of The Liver Are As Follows;

1)                 The removal of toxins that have been absorbed from the intestines.

2)                 The storage of simple sugar as glycogen which is released as glucose.

3)                 The final treatment of fats so they can be more efficiently utilized by the cells.

4)                 The storage of certain vitamins including a, d and some of the b group.

5)                 The production of bile from the pigment of broken down red blood cells.

6)                 The formation of antibodies which act against disease organisms.

7)                 The production of certain blood plasma proteins such as fibrinogen and albumin.

8)                 The removal of urea, a waste product from amino acids.

GALLBLADDER

A muscular sac that serves as a storage pouch for bile which is secreted when fat is present in the food.

PANCREAS

The Pancreas Produces;

1)          Pancreatic juice which act with the enzymes amylopsin, trypsin and lipase which in turn act on starches, proteins and fats.

2)          Insulin which is released directly into the blood and has the function of regulating the sugar level in the body.