Explain human digestive system..
Answers
Answer:
What is digestive system?
The digestive system is made up of the digestive tract and other organs that helps the body to break down and absorb the food. It is a long twisting tube that starts at mouth and goes through the esophagus , stomach , small intestine , large intestine and anus.
It breaks down food into nutrients such as carbohydrates, fats and proteins. Then they can be absorbed into the bloodstream so that body can use them for energy, growth and repair. Waste materials are removed from the body as faeces.
It also contains other organs like pancreas, liver and gallbladder.
How does the digestive system works ?
Each organ of digestive system plays an important role in digestion :-
Mouth:-
The mouth is the beginning of the digestive tract. When we eats food, the teeth chew food into small pieces. Glands in the cheeks and under the tongue produce saliva that coats the food, making it easier to chewed and swallowed.
Saliva also contains enzymes that start to digest the carbohydrates in food.
Esophagus:-
The esophagus is the muscular tube that carries food from the mouth to the stomach after it is swallowed. A ring of muscle at the end of the esophagus relaxes to let food into the stomach and contracts to prevent stomach contents from escaping back up the esophagus.
Stomach:-
The stomach wall produces gastric juice (hydrochloric acid and enzymes) that digests proteins. The stomach acts like concrete mixer, churning and mixing food with gastric juice to form chyme - a thick, soupy liquid.
Small intestine:-
Small intestine is called small because it is 3.5cm in diameter, but it is 5m long to provide lots of area for absorption. Most of the chemical digestion of proteins, fats and carbohydrates is completed in the small intestine.
Bile from the gallbladder and enzymes in digestive juices from the pancreas empty into the upper section of the small intestine and help to break down protein into amino acid and fat into fatty acids. These smaller particles, along with sugars , vitamins and minerals, are absorbed into the bloodstream through the wall of the small intestine.
Large intestine and anus:-
The lining of the large intestine absorbs water, mineral salt and vitamins. Undigested fiber is mixed with mucus and bacteria - which partly break down the fibre - to norish the cells of the large intestine wall and so help keep the 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.
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma.
Answer for Explain digestion. Draw a well labelled diagram of a human digestive system and its associated gland. Also mention the role of every organ shown in the diagram.
(i) Food is crushed and cut in the mouth with the help of teeth and is mixed with saliva that is secreted by three salivary glands(one below the tongue and two at the side of the jaw) to make it wet and slippery, this process is known as mastication.
(ii) Saliva contains amylase that breaks down complex carbohydrates and the tongue helps in pushing the food to the next part of the alimentary canal.
(iii) The soft food then passes through the oesophagus in a wave-like movement known as a peristaltic movement.
Role of organs are:
Mouth
The mouth is the beginning of the digestive tract. In fact, digestion starts before we even take a bite. Our salivary glands get active as we see and smell the food. After we start eating, we chew our food into pieces that are more easily digested. Your saliva mixes with the food to begin to break it down into a form your body can absorb and use. .
Esophagus
The esophagus receives food from our mouth when we swallow. The epiglottis is a small flap that folds over the windpipe as we swallow food this preents it from choking (when food goes into your windpipe). A series of muscular contractions within the esophagus called peristalsis delivers food to your stomach.
Stomach
The stomach is a hollow organ, or "container," that holds food while it is being mixed with stomach enzymes. These enzymes continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are processed enough, they’re released into the small intestine.
Small intestine
Made up of three segments -- the duodenum, jejunum, and ileum -- the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also works in this organ, moving food through and mixing it with digestive juices from the pancreas and liver.
The duodenum is the first segment of the small intestine. It’s largely responsible for the continuous breaking-down process. The jejunum and ileum lower in the intestine are mainly responsible for absorption of nutrients into the bloodstream.
Pancreas
The pancreas secretes digestive enzymes into the duodenum that break down protein, fats and carbohydrates. The pancreas also makes insulin, passing it directly into the bloodstream. Insulin is the chief hormone in your body for metabolizing sugar.
Liver
The liver has many functions, but its main job within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat and some vitamins.
Gallbladder
The gallbladder stores and concentrates bile from the liver, and then releases it into the duodenum in the small intestine to help absorb and digest fats.
Colon (large intestine)
The large intestine, or colon, is responsible for processing waste so that emptying the bowels is easy and convenient. It’s a 6-foot long muscular tube that connects the small intestine to the rectum.
The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum.
Rectum
The rectum is a straight, 8-inch chamber that connects the colon to the anus. The rectum's job is to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not.
Anus
The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is able to detect rectal contents.
