Stomach

Stomach (ventricle) is located below the body cavity constriction or above abdominal cavity. Stomach has some primary functions. Such us stroring food,  mixing food, and preparing the hydrolisis process of protein enzymes.

Stomach consists of three parts. First, food enters the stomach through cardiac. Then, it goes toward fundus and pylorus. Pylorus is close to the lock muscle (valve) that controls food transfer into the intestine.

Stomach wall is composed of some muscular layers. Longitudinal muscles in the outer layers, circular muscles in the middle layer, and oblique muscle in the inner layer. 

When these muscles contract, food in stomach will mix all together with gastric acid become chymus.

Stomach wall has glands which producing mucose, gastric acid, and gastrine hormone.

1. Mucus, is produced by mucose cells.

2. Gastric acid consists of several substances as follows :

     a. Hydrochloryd acid, is produced by parietal cells, it is necesary to kill germs, create acidic environment (with a pH nearly to 1), stimulate secretion of intestine juice, stimulate the opening and closing of pylorus sphincter, and activate pepsinogen into pepsin.

       b. Pepsin is a protease enzyme which breaks down protein into pepton.

       c. Rennin, is an enzyme which has function to curdle the milk protein (casein). Generally it's found in young mammals.

       d. Lipase, is an enzyme which breaks down lipid into fatty acid and glycerol. It is produced by salivary gland that is accumulated in stomach instead of stomach.

3. Gastrin hormone, is a hormone tghat stimulates secretion of gastric acid in stomach.