what is digestive system?
Answers
Explanation:
The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion. Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages.
The first stage is the cephalic phase of digestion which begins with gastric secretions in response to the sight and smell of food. This stage includes the mechanical breakdown of food by chewing, and the chemical breakdown by digestive enzymes, that takes place in the mouth.
Answer and Explanation:
What is the Digestive System?
Your digestive system breaks down the food you eat into nutrients such as carbohydrates, fats and proteins. They can then be absorbed into your bloodstream so your body can use them for energy, growth and repair. Unused materials are discarded. The digestive system is made up of the digestive tract and other organs that help the body break down and absorb food. Your digestive tract is a long, twisting tube that starts at your mouth, and then involves your oesophagus, stomach, small intestine, large intestine and anus. Other organs that form part of the digestive system are the pancreas, liver and gallbladder. Each organ of the digestive system has an important role in digestion.
Mouth
When you eat, your teeth chew food into very small pieces. Glands in your cheeks and under your tongue produce saliva that coats the food, making it easier to be chewed and swallowed.
Saliva also contains enzymes that start the digestion of the carbohydrates in your food.
Oesophagus
Your oesophagus is the muscular tube that carries food from your mouth to your stomach after you swallow. A ring of muscle at the end of the oesophagus relaxes to let food into your stomach and contracts to prevent stomach contents from escaping back up the oesophagus.
Stomach
Your stomach wall produces gastric juice (hydrochloric acid and enzymes) that digests proteins. The stomach acts like a concrete mixer, churning and mixing food with gastric juice to form chyme — a thick, soupy liquid.
Small intestine
Bile from your gall bladder and enzymes in digestive juices from your pancreas empty into the upper section of your small intestine and help to break down protein into amino acids and fat into fatty acids. These smaller particles, along with sugars, vitamins and minerals, are absorbed into the bloodstream through the wall of your small intestine.
It is called small because it is about 3.5 cm in diameter but it is about 5 m long to provide lots of area for absorption. Most of the chemical digestion of proteins, fats and carbohydrates is completed in your small intestine.
Large intestine and anus
The lining of your large intestine absorbs water, mineral salts and vitamins. Undigested fibre is mixed with mucus and bacteria — which partly break down the fibre — to nourish the cells of the large intestine wall and so help keep your large intestine healthy. Faeces are formed and stored in the last part of the large intestine (the rectum) before being passed out of the body through the anus.