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Posted by Chester Morton / Saturday 14 May 2016 / No comments
The digestive system in humans
THE DIGESTIVE SYSTEM IN HUMAN
Definition
Digestion refers to the process whereby food substances are
broken down into smaller particles for easy absorption. Digestion usually
begins in the mouth and ends in the small intestines.
The Mouth
In the mouth, the food is chew and broken down into smaller
particles. The salivary gland secretes an enzyme call salivary amylase to begin
the digestion of carbohydrate into maltose; it also secretes saliva to softens
the food and provide a pH which is slightly alkaline to enable salivary amylase
to act properly.
Oesophagus
Here the enzyme calls salivary amylase continuous the
conversion of carbohydrate into maltose.
The stomach
In the stomach, digestion of protein begins here. The
protease gland secretes enzymes call Pepsin and Renin and also hydrochloric acid
which provides the suitable pH for Pepsin and Renin to act. The enzyme Pepsin
breaks down protein into polypeptides and Renin coagulates and solidifies
liquid protein for enzyme Pepsin to breakdown.
The duodenum
When the lives the stomach and on it way into the small
intestine, the pancreas secretes the pancreatic juices which contain enzymes
such as amylase to continue the conversion of carbohydrate, pepsin and renin to
continue the conversion of protein into polypeptide and lipases to convert
lipids into smaller droplets. The gallbladder also secretes the bile which is
stored in the liver. The bile contains an enzyme call lipase which begins the
conversion of fats and oil(lipids) into smaller droplets.
Small intestine
Digestion ends in the small intestine. The small intestine
produces enzymes which complete the digestion of food substances. Examples
include lactase to convert lactose to glucose and galactose. It also absorbs
digested food substances into the body. The end product of carbohydrate is
glucose, fructose and galactose; protein is amino acids and fats and
oil(lipids) is fatty acids and glycerol.
Large intestine
This is the last part of the digestive system in most
vertebrates; it extracts water and salt from solid wastes before they are
eliminated from the body. It absorbs water, potassium and some fat soluble
vitamins.
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