Explain the process of
digestion in humans
Answers
Answer: The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). 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.
Saliva contains digestive enzymes called amylase, and lingual lipase, secreted by the salivary glands and serous glands on the tongue. The enzymes start to break down the food in the mouth. Chewing, in which the food is mixed with saliva, begins the mechanical process of digestion. This produces a bolus which can be swallowed down the esophagus to enter the stomach. In the stomach the gastric phase of digestion takes place. The food is further broken down by mixing with gastric acid until it passes into the duodenum, in the third intestinal phase of digestion, where it is mixed with a number of enzymes produced by the pancreas. Digestion is helped by the chewing of food carried out by the muscles of mastication, the tongue, and the teeth, and also by the contractions of peristalsis, and segmentation. Gastric acid, and the production of mucus in the stomach, are essential for the continuation of digestion.
Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the colon of the large intestine. The waste products of digestion (feces) are defecated from the anus via the rectum.
Explanation:
Answer:
The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body.
Explanation:
Humans have holozoic nutrition, that means the food is consumed as a whole and the digestion occurs internally. It can be described as:
1. Ingestion of food- The food is taken in the oral cavity in the process called the ingestion. The teeth help in grinding of the food, salivary amylase helps in partial breakdown of the starch and the tongue helps in mixing the food with saliva and helps in swallowing it. The food is now called bolus.
2. Digestion- The process of break-down of complex substances into simpler substances is called digestion and it starts with the mouth where physical break-down occurs along with some chemical digestion. The bolus is swallowed in and it arrives in stomach where the digestion of proteins occurs due to presence of the enzyme pepsin. Bolus is now called the chyme. This chyme now moves into the small intestine where rest of the process of digestion will be completed. The pancreatic juice, the intestinal juice and the bile will result in breakdown of carbohydrates, fats and the rest of the proteins. The chyme is now called the chyle and it moves to the large intestine where the water is absorbed.
3. Absorption- The digested food is absorbed via the finger-like projections present on the inner surface of the small-intestine and the reach the blood stream.
4. Assimilation- The absorbed food is then used by different tissues for the energy generation. The excess food is stored as glycogen in the liver and s fats in adipose tissue.
5. Excretion- The undigested material passes from the small-intestine to the rectum of the large-intestine, from where it is removed from the body through anus.