Essay Example on The digestive system describes the alimentary Canal









The digestive system describes the alimentary canal its accessory organs and a variety of digestive processes that prepare food eaten in the diet for absorption In this assessment I will be explaining the purpose of digestion the several mechanisms for moving food along the GI tract Also explain the chemical digestion of protein carbohydrates and lipids Digestion is defined as the mechanical and chemical breaking down of food into smaller parts to a form that can be absorbed into the bloodstream The end of the digestive process is defecation The food enters the mouth is chewed by the teeth and broken down by the saliva from the salivary glands It travels down the oesophagus and into the stomach where acid breaks down most of the food The remainder goes through the small intestine then through the large intestine or bowel and comes out as waste through the anus The purpose of the digestive tract is to break down our food into absorbable nutrients Our food consists of carbohydrates proteins and fats which need to be broken down into sugars amino acids and fatty acids If our digestive system can t break down our food adequately our body could absorb macromolecules which could include bacteria This could lead to infection irritation to the intestine intestinal toxaemia or other diseases In other words without adequate digestion there is no possible good health The digestive system is made up of the gastrointestinal GI tract also called the digestive tract 

The GI tract is a long muscular organs about 8 to 9metre joined in a long twisting tube that move food from the mouth to the anus where the body absorbs and digests nutrients along the way with the elimination of leftover waste stools or faeces at the anus The digestive tract breaks down food and drink into usable components that the body absorbs and uses for energy This energy is used for growth repair and maintenance of cells that make up the human body The digestive tract consists of the mouth oesophagus stomach small intestine large intestine rectum and anus The digestive process begins in the mouth with the help of the tongue and teeth to begin digestion by the process of chewing and breaking down food small enough to be swallowed This chewing process as well as carbohydrates in food stimulate the salivary glands to secrete saliva Saliva contains digestive enzymes called salivary amylase that break down starch and fat Swallowing is a complex process involving muscles and nerves The tongue pushes food back into the throat or pharynx and into the opening of oesophagus The oesophagus is a 25 cm long tube that transports the swallowed food from the mouth to the stomach by the support of peristalsis As the food leaves the oesophagus the lower esophageal sphincter opens to allow the food to exit The oesophagus prevents food from regurgitating and re entering the throat by the upper esophageal sphincter The food then enters the stomach The stomach is a muscular J shaped sac attached to the oesophagus and temporarily stores ingested food It can hold up to 2 litres in an adult and has a thick muscular wall covered by about 3 mm of mucous

The stomach mixes the partially digested contents by mechanical action peristalsis This mixing is also aided by enzymes pepsin and hydrochloric acid and to break down proteins in the food and also destroys any dangerous bacteria in the food After several hours when the food has been further reduced in size and mixed with the gastric juices the stomach slowly transfer its contents inside small intestine The small intestine is about 6 metres in an adult and is designed to have maximum surface area for its length by having villi and microvilli It's in the small intestine where most of the nutrients from the food will be absorbed As nutrients leave the small intestine they are absorbed into the bloodstream The nutrients in the bloodstream are absorbed by the liver and changed into glycogen and proteins After that it sent back into the bloodstream Most liquids move through the small intestine within an hour while solids take about three to five hours with fats and proteins taking the longest After passing through the small intestine any food left passed into the large intestine The large intestine is about 5 feet long and is curved like an upside down U shape It also refer to as colon Most of the digestion and absorption of nutrients from food has already occurred by the time it reaches the intestine It absorb water and salt from food in order to produce solid waste faeces as it ferments 

At the end of the digestive system the faeces will be pushed through the rectum and ends at anus Nutrients are important substances that allow body to perform required daily activities Carbohydrates fats and proteins are the major nutrients our body needs for growth repair movement and maintaining homeostasis These macromolecules are broken down and absorbed into the body at different rates and into specific forms as they travel through the organs in digestive system Carbohydrates are body energy source that be found in the forms of starch sugar and fiber Digestion begins in the mouth where the process of chewing mechanically breaks food into small pieces Enzymes in the saliva initiate chemical digestion When swallow partially digested carbohydrate travel down oesophagus to the stomach with little additional digestion From there carbohydrates move into the small intestine where enzymes released by the pancreas break them into simple forms to be absorbed into the bloodstream Fibre is indigestible and passes through gastrointestinal tract without being broken down Most lipids that are consume in diet are fats Some digestion occurs in the mouth and the stomach but most takes place in the small intestine Bile is produced by

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