Stomach Is Digestive Human System, Stomach (ventricle ) is located below the body cavity constriction or above abdominal cavity. Stomach has some primary function, such as storing food, mixing food, and preparing the hydrolysis process of protein enzymes.
Stomach consists of three part. Firstly, food enters the stomach through cadiac. Then, It goes toward fundus and pylorus. Pylorus is closes to the lock muscle (valve) that controls food transfer into the intestine.
Stomach wall is composed of some muscular layers, longitudinal muscle in the outer layer, circular muscles in the middle layer, and oblique muscle in the inner layer. When these muscles contract, the food in stomach will mix all together with gastric acid and become chymus.
Stomach wall has stomach glands producing mucose, gastric acid, and gastrin hormone.
1. Mucus is produced by mucosa cells
2. Gastric acid consists of several substances as follows.
a. Hydrochloride acid (HCI) is produced by pariental cells. It is necessary 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 is 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 that stimulates secretion of gastric acid in stomach.
In stomach, food is digested into chime, an acidic yellowish substance. When chyme enters intestine, the acidity of chyme is quickly neutralized by alkaline liquid secreted from liver and pancreas.
Stomach produces gastric acid in which pepsin breaks down protein. Stomach itself of made of protein. Then, why is stomach not digested? Stomach wall is covered by thick mucosa layer that protects the stomach from acid, and even pepsin that enters the stomach is inactive. If damage occurs, stomach will replace a half million of its cells in every minute.