Human Digestive System

Amylase is an enzyme that catalyses the hydrolysis of starch into sugars.

The goblet cells in the intestine is present in mucosa.

Peristalsis is a distinctive pattern of smooth muscle contractions that propels food distally through the oesophagus and intestines. It is an automatic and important process that moves food through the digestive system.

The sublingual gland is the smallest of the three glands. It is situated beneath the mucous membrane of the floor of the mouth at the side of the fraenulum, in contact with the sublingual depression on the inner surface of the mandible. It is narrow, flattened, shaped somewhat like an almond and weighs nearly 2 gm.

The pylorus is the region of stomach that connects to duodenum. The internal surface of pylorus is covered with a mucous membrane lining that secretes gastric juice.

Amylase is secreted by salivary ducts in the mouth, and helps to digest starch into simple cabohydrates.

Bile or gall is a bitter tasting, dark green to yellowish brown fluid produced by the liver of most vertebrates that aids the process of digestion of lipids in the small intestine. In many species, it is stored in the gallbladder and is discharged into the duodenum during digestion.

Ptyalin or amylase present in saliva catalyses the hydrolysis of starch into maltose and dextrin.

Intestinal villi are small, finger like projections that protrude from the epithelial lining of the intestinal wall. Each villus is approximately 0.5 to 1.6 (millimetres) in length and has many microvilli. The villi increase the surface area of the ileum for absorption.

Rennin is a proteolytic enzyme synthesised by chief cells in the stomach. Its role in digestion is to curdle or coagulate milk in stomach.

The vermiform appendix is a small, finger-sized structure found at the end of our small caecum, and it is located near the beginning of the large intestine.

The saliva contains ptyalin or salivary amylase, which starts degrading the starch where the chain is linear. It is an enzyme that breaks the bond joining two sugars together and forms fragments of soluble starches. It then breaks these down further, and the final product is a unit of two glucose molecules known as maltose. This substance is then broken down to glucose in the intestine.

Chyme is a thick semifluid mass of partially digested food and digestive secretion, i.e. formed in the stomach and intestine during digestion. 

Bile does not contain any enzymes for the breakdowm of complex food material. They simply emulsify the fats.

Biliverdin and bilirubin are the pigments that give bile its colour. These are produced by the breakdown of the dead and worn out red blood cells. Biliverdin is a green pigment formed by the catabolism of haemoglobin, and converted to bilirubin in the liver. It may also arise from oxidation of bilirubin.