The contents of the sandwich are then mixed with saliva to moisten it and to make it easier to swallow. The sandwich is formed into a bolus and the tongue pushes the bolus to the back of the throat and then it is swallowed. The saliva contains an enzyme called amylase which breaks down starch (the bread) into sugars. The sandwich passes down the oesophagus and after 3-6 seconds of leaving the mouth, the food will reach the stomach by the involuntary wave like muscular contractions, known as peristalsis. The epiglottis stops any of the sandwich entering the windpipe by covering the windpipe hole.
It moves food through and mixing it with digestive secretions from the pancreas and liver. The duodenum is mainly responsible for the continuous breaking-down process, with the jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream.
The tongue and teeth move the food around, mixing it with the saliva, with all 32 teeth tearing and crushing it to break it down further into a softer composition called a bolus. During the swallowing process, the epiglottis blocks the air passage to prevent food from going into the lungs. Once swallowed, the esophagus movies it by way of peristalsis, or squeezing and relaxing of the muscles, down into the stomach. The stomach acts as a holding tank for the food while it mixes further with gastric juices such as enzymes and acids from its lining, to break down the bolus into a thick creamy substance called chyme. After turning into chyme, it is sufficiently processed enough to release into the small intestine.
SCI/241 THE SCIENCE OF NUTRITION January13,2012 Human Digestion How the does the digestive system works to absorbs nutrients? Digestion starts with the smell of food, it activates the salivary glands. The gland secret saliva that moistens food, it also contains a digestive enzyme called amylase that breaks down some carbohydrates before it leaves the mouth. Then the food is swallowed and goes into the lumen through the esophagus. The esophagus muscles contractions called peristalsis forces the food through the sphincter valve and into the stomach.
It is produced in the liver by fructokinase (ghr.nlm.nih.gov, n.d.). The role of aldolase b during the metabolism of fructose: Aldolase b is required for the breakdown of carbohydrates. It acts as a catalyst in the glycolytic-gluconeogenic pathway. The metabolism of fructose also requires aldolase b. After fructose is absorbed it is phosphorylated by fructokinase to form F1P.
The digestive system helps break down this food into small pieces, the enzymes within the digestive system breaks the protein into amino acids, fatty acids and carbohydrates into glucose. The sugar, amino acids and fatty acids are able to be used as energy sources in the human by body cells. Energy requirements are ordinarily expressed in terms of calories. The calorie used in nutritional discussions is actually the "large calorie “Calorie. This is really a kilocalorie the amount of heat energy required to raise the temperature of one kilogram (about 1 quart) of water one degree Celsius.
* teeth help in physical digestion by cutting the food into small pieces , chewing it and grinding it . * salivary glands secrete saliva which help in the chemical digestion of the food apart from making it wet . * tongue helps in mixing this broken food with saliva – which wets the food in our mouth so that it can be swallowed more easily . * saliva contains enzyme – salivary amylase which digests the starch present in the food into sugar . * because food remains in the mouth only for a short time , so the digestion of the food remains incomplete in the mouth .
From there the food moves to the small intestine. The small intestine is a long tube loosely coiled in the stomach. The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile from the liver. Bile is a compound that aids in the digestion of fat and eliminates waste products from the blood. Peristalsis
Insulin is released by the beta cells in our pancreas into our blood stream when our blood glucose level is high. This is done to try and decrease our blood glucose levels. If our blood glucose levels are low, our pancrease then secretes the hormone glucagon which is then used by the liver to release glucose into our blood stream. A Local Hormone are hormones which act locally without first entering the blood stream. An example of a local hormone is Gastrin which is a polypeptide hormone secreted by the mucous lining in our stomach.