7th Class Science Respiration in Organisms Digestive System of Human

Digestive System of Human

Category : 7th Class

Digestive system of Human

Human digestive system is consisted of many parts. Each of the parts has a distinct function to perform.

Look at the following picture of human digestive system

Oral or Buccal Cavity

Our mouth is the first organ of the digestive system, which is known as oral or buccal cavity. When we eat food, the teeth part of our mouth breaks food into small pieces. Oral cavity contains a muscular organ called tongue. It helps in mixing the food with saliva secreted by salivary gland. Thus digestion of food begins in the mouth.

Esophagus

Esophagus is a tube like structure, which brings food from mouth to stomach. No action on food takes place in the esophagus.

Stomach

Stomach is the largest part of the alimentary canal. It secretes mucus, hydrochloric acid and digestive juices. Hydrochloric acid kills harmful bacteria that enter through mouth with food. The partially digested food then goes from stomach into small intestine.

Small Intestine

The length of small intestine is about 7.5 meters. It is called small intestine because of its narrow piped shape. The wall of small intestine secretes a juice called intestinal juice. Intestinal juice breaks down the carbohydrate into glucose and protein into amino acid. The complete digestion and absorption of digested food takes place inside the small intestine. Small intestine receives digestive juice from pancreas and liver. Pancreas secretes pancreatic juice. It breaks down the fats into fatty acid and proteins, carbohydrates into its simplest form. Liver also secretes enzymes called bile. Bile is temporally stored inside gallbladder and it helps for the digestion of fat. Villus of small intestine absorbs the digested food and send it to all the parts of the body.

Large Intestine

The large intestine consists of cecum and colon. The main function of large intestine is to absorb extra water from the indigestible food and then pass it to the rectum. The feces (indigestible food) is stored in the rectum for a certain period and then the stored feces is expelled out of body.