digestive system

DIGESTIVE SYSTEM

The digestive system is the set of organs (mouth, pharynx, esophagus, stomach, small intestine and large intestine) responsible for the process of digestion, ie the transformation of food so they can be absorbed and utilized by body cells .
The function performed is the transport (food), secretion (digestive juices), absorption (nutrients) and excretion (through the process of defecation).

Anatomical description

EsophagusThe esophagus is a tube or muscle membrane that extends from the pharynx to the stomach. Of the incisors to the cardia (the portion where the esophagus is continuous with the stomach) is about 40 cm. The esophagus begins at the neck, chest and traverses into the abdomen through the esophageal opening of the diaphragm. Usually it is a virtual cavity. (Ie the walls are joined and only open when the bolus passes). The esophagus reaches measure 25 cm and has a structure consisting of two layers of muscles, allowing the contraction and relaxation downstream of the esophagus. These waves are called peristalsis and are causing the spread of food to the estómago.Es just a step area of the bolus, and is the union of different holes, the mouth, the nose, ears and larynx 

Stomach

The stomach is an organ which accumulates comida.Varia so by state filling (amount of nutritional content present in the stomach) that is usually shaped like a J. It consists of several parts that are: fundus, body, antrum and pylorus. Less extensive edge is called lesser curvature and the other, greater curvature. The cardia is the boundary between the esophagus and stomach and pylorus is the boundary between stomach and small intestine. In an individual is about 25cm of the cardia to the pylorus and the transverse diameter is 12cm.
Is responsible for making the chemical transformation as gastric juices transform the bolus that had previously been mechanically processed (from the mouth.)
Inside are two main types of cells, parietal cells, which secrete hydrochloric acid (HCL) and intrinsic factor, a glycoprotein used in the absorption of vitamin B12 in the small intestine and also contains the principal cells or oxyntic the which secrete pepsinogen, the precursor enzyme is activated by the HCL form pepsins 3 each.
The secretion of gastric juice is regulated by both the nervous system and the endocrine system, a process in which they operate: gastrin, cholecystokinin (CCK), secretin and gastric inhibitory peptide (PIG).
In the Stomach digestion is performed:

    * Proteins (mainly pepsin).
    * Lipids.
    * NO Carbohydrate digestion occurs.
    * Other functions of the stomach are the elimination of bacterial flora food comes with the action of hydrochloric acid.

Small intestine
The small intestine starts in the duodenum (after the pylorus) and ends at the ileocecal valve, which joins the first part of the large intestine. Its length is variable and its size decreases gradually from its origin to the ileocecal valve and measures 6 to 7 feet long.
In the small intestine to absorb nutrients and digest food. The tube is filled with villi that increase the absorption surface.
The duodenum, part of the small intestine is about 25 to 30 cm in length, the small intestine consists of a proximal or distal jejunum and ileum and, the boundary between the two parts is not very apparent. The duodenum is attached to the jejunum after 30cm from the pylorus.
The jejunum-ileum is part of the small intestine that is characterized by a relatively fixed ends: The first originates in the duodenum and the second is limited to the ileocecal valve and the first portion of the blind. Its size decreases slowly but steadily toward the large intestine. The boundary between the jejunum and ileum is not noticeable. The small intestine has numerous villi which increase the surface of intestinal absorption of nutrients and proteins. The small intestine, mainly the duodenum, pour a variety of secretions such as bile and pancreatic juice.

Large intestine

The large intestine starts from the ileocecal valve in a blind pouch called the rising of the vermiform appendix and ends at the rectum. From the cecum to the rectum describes a series of curves, forming a frame in the center are the loops of ileum jejunum. Its length is variable, between 120 and 160 cm, and its size gradually decreases, with the narrowest portion of the region where it joins the rectum or rectosigmoid junction where its diameter is not usually exceed 3 cm, while the blind is 6 or 7 cm.
After the blind, the large intestine is known as the ascending colon, with a length of 15cm, to give rise to the third portion is the transverse colon with an average length of 50cm, giving rise to a fourth portion which is the descending colon 10cm length. Finally, unlike the sigmoid colon, rectum and anus. The rectum is the terminal part of the digestive tract.

Pancreas
Gland is intimately connected to the duodenum, is of mixed origin, secretes hormones to control blood sugar and pancreatic juice is poured into the intestine through the pancreatic duct, and intervenes and helps digestion, their secretions are important in the digestion of food.

Liver

The liver is the largest internal organ of the body. Weighs 1500 grams. It has three lobes, right, left and caudate, which in turn are divided into segmentos.Las bile ducts are excretory pathways of the liver, bile is driven them into the duodenum. Usually get two channels: left and right that converge together to form a single tube. The hepatic duct receives duct thinner, the cystic duct, which comes from the gallbladder hosted on the visceral surface of liver. Meeting of the cystic and hepatic ducts forms the common bile duct, which descends into the duodenum, which flows along with the excretory duct of the pancreas. The gallbladder is a reservoir muscle membrane on derivation of the main bile duct. Contains about 50-60 cc of bile. It is slightly oval or pear-shaped and its diameter is about 8 to 10 cm.

Spleen
The spleen, its main functions should be considered an organ of the circulatory system, but for his great ability to absorb nutrients through the blood, may be added to the annexes of the digestive apparatus. Its size depends on the amount of blood it contains.