Digestive System

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Introduction
Digestion is the process by which complex particles are breaked down to simple particles that are most easily absorbed into blood stream. Digestion is a form catabolism ,a break down of large food molecules to smaller ones. It is one of the life processes which includes organs such as mouth, oesophagus,stomach,small intestine,large intestine and anus.Each of the organs does many processes which makes the digestion process easy.
The organs which takes place in digestion process are :
Mouth

In animal anatomy the mouth is the first part of alimentary canal that receives food.The food has to be processed to generate particle which are small and of the same texture.this is achieved by crushing by the teeth.Since the lining of the canal is soft ,the food is also wetted to make it passage smooth. Mouth contains a fluid called saliva which is secreted by salivary glands.The saliva contains a enzyme called salivary amylase that which is a complex molecule to give sugar. The food is chewed thoroughly with saliva and moved around the mouth while chewing by muscular tongue. In animal anatomy, the mouth is the first portion of the alimentary canal that receives food. The adjectival form is "buccal" derived from Latin bucca (lit. "cheek"), hence "buccal cavity", "buccal nerve", "buccal artery", etc. Some animal phyla, including vertebrates, have a complete digestive system, with a mouth at one end and an anus at the other. Which end forms first in ontogeny is a criterion used to classify animals into protostome and deuterostome. In humans, the first space of the mouth is the mouth cavity, bounded laterally and anteriorly by the alveolar arches (containing the teeth), and posteriorly by the isthmus of the fauces

Oesophagus

It is the organ through the food is passed from the mouth to the stomach. It is necessary to move the food in a regulated manner along the digestive tube so that it can be processed properly in each part. The lining of canal has muscles that contract rhythmically in order to push the food forward. This rhythmic movement is called peristalsis. This function is to make the movement easier. These peristaltic movements occur all along the gut. Atlast the food is taken from the mouth to the stomach. The esophagus (oesophagus, commonly known as the gullet) is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach. The word esophagus is derived from the Latin œsophagus, which derives from the Greek word oisophagos, lit. "entrance for eating." In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through posterior mediastinum in thorax and enters abdomen through a hole in the diaphragm at the level of the tenth thoracic vertebrae (T10). It is usually about 25cm, but extreme variations have been recorded ranging 10–50 cm long depending on individual height. It is divided into cervical, thoracic and abdominal parts. Due to the inferior pharyngeal constrictor muscle, the entry to the esophagus opens only when swallowing or vomiting. Stomach

The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices. These digestion functions are taken care of by the gastric glands which secretes gastric juices.The gastric gland is present in the wall of the stomach. These gland produces hydrochloric acid (hcl),mucus, pepsin. Hcl creates an acidic medium which facilitates the action of enzyme pepsin. It kills the microorganisms .Mucus protects the inner lining of the stomach from the action of the acid under normal conditions. Pepsin digest...
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