Explanation and study of the digestive system
The digestive system is formed by a long tube that begins with the oral cavity and ends in the anus this has structures that connect and glands. The digestive system has the function of four processes and it is ingestion to transport digestion and absorption and defecation of waste products. Ingestion begins by transporting the passage of food through him had digestive for this transportationand parasympathetic, also the SNA participates by controlling the secretions. We know that digestion is mechanical by chewing and automatic by peristalsism (it is the set of digestive tract contraction movements). Absorption begins by means of chemical mediators since specific molecules are absorbed in each part of the digestive tract. As the final part of this first process the evacuation of feces.
The digestive tract is formed by about four layers that are the mucosa, muscle, muscular mucosa (longitudinal and oblique fibers) and the adventitious layer. We continue with the esophagus, sphincter of the cardias,
stomach, pyloric sphincter, small intestine (which is divided into a duodenum where the greatest absorption and the jejunum and ileum, large intestine (this divides in three portions ascending colon, transverse colon and descending colon), the rectum and the anus and the anus.
The digestive system begins by the mouth is covered by a mucous membrane with a stratified flat epithelium non -keratinized and limited by cheeks and lips. In the mouth we find the tongue that is the one that works as a diapédesis because it has 18 skeletal muscles, it is divided into three base areas, body, and tip, and it is covered by a mucous membrane, in the superficial part are the taste papillaeThose are in charge of the sense of taste, and they are also part during chewing and swallowing. The roof of the mouth is formed by the palate that consists of two parts: the hard palate, formed by the upper maxillary and palatine bones and the other the soft palate, formed by pairs lined with mucosa, which are inserted in front ofThe hard and behind the palate is free and presents a conical projection called uvula (the famous bell). On the sides of the soft palate there are two muscles coated with vertical mucous replicues that constitute the two previous pillars and the two posterior pillars of the palate. In the mouth a mechanical and chemical processes are fulfilled.
Mechanical processes are chewing to crush and impregnate food with saliva, the chemical process is performed by amylase or ptialine this is what allows you to unfold the starches, also alkalinizes the alkalinizes the food bolus. After the oral cavity, the pharynx continues, this fulfills two functions a respiratory and another digestive transporting the food to the esophagus. In the pharynx the voluntary part of the swallowing digestion ends and involuntary digestion begins because the esophagus has innervation of the autonomic nervous system, which is why there is peristaltism, also the esophagus has a function of food bolus transfer, in addition to itsDistal portion is the sphincter of the cardias which is the one that prevents the gastric content from being returned to the esophagus, to avoid being injured by the mucosa for its acid and presence of proteolytic enzymes (these help digest the proteins contained in food) . The sphincter of the cardias or gastroesophagic is at the level of the diaphragm and composed of smooth muscle. When at rest, the lower esophageal sphincter is in a tonic state and swallowing, the lower esophageal sphor.end of the esophagus and the closure of the lower esophageal sphincter occurs.
The physiological mechanism of relaxation and contraction of the sphincter is not clear, but it is believed that it is vaguely mediated, sympathetic via, with the intervention of preganglionic and post -ganglionic cholinergic nerves. The contraction of these of these is given by the stomach wall that are innervated by the vago nerve, which is the one that stimulates the contraction of the musculature. Then we find the thin intestine that anatomically forms the duodenum, Yeyuno and íleon, the duodeno relates to the stomach, liver and pancreas forming a functional unit receiving the chime that becomes quilo, of the stomach, is also the blister ofVáter or duodenal papilla, where the Oddi sphincter is regulating the flow of pancreatic juice that spills in the duodenum, pancreatic juice is formed by water, mineral salts, sodium bicarbonate and enzymes such as enzyme proteases (tripsin,chemotrypsin and carboxympidase) that act in the decomposition of proteins, the pancreatic amylase enzyme that the starches break down, the nucleous enzymes such as the deoxyribonuclease and the ribonucleases, and the lipase enzyme.
And we also have the duodenum that serves a very important function, it can be said that it is the small intestine part that performs the greatest absorption of food since it has villi and an aqueous medium.
Another juice that spills in the duodenum is the bile that is also stored in the gallbladder which also acts on fats as a detergent. Secretin and an enzymatic component that is irrigated inactively, thanks to the action of cholecychinine in response to the presence of acidity and presence of the duodenal chime. In its walls we find the Lieberkühn cell, Brunner glands, which provide an aqueous medium for the absorption and production of alkaline fluids to protect the mucosa of the acides that is in the chime of the stomach, respectively. Throughout the small intestine are the peyer plates that are integrated with B lymphocytes that produce immunoglobulin to which it protects preventing microorganisms from being absorbed by mucous membranes.
Then we find the ileocecal valve that separates them from the large intestine;This is made up of the appendix, the colon (which is divided into ascending, transverse, descending and the sigmoid colon), the rectum and the anus.
As another important part we have the large intestine which has an approximate diameter of 6 cm and a length of 1.5-1.8 m, it is understood that its divisions of the large intestine are those of the ascending colon, it is in vertical position and on the right side of the abdomen spreading to the lower edge of the liver (hepatic angle);The ileocecal valve that allows the passage of the ileum material to the large intestine but not in the opposite direction, the transverse colon crosses horizontally the abdomen below the liver, stomach and spleen (splenic angle) but above the small intestine.
And as the latter, but not least we have the tongue which is formed by skeletal muscles covered by a mucosa with a non -keratinized stratified flat epithelium. Then the accessory glands such as the salivary glands, the pancreas and the liver. The salivary glands which secrete saliva contains approximate 95% of water and the other 5% is salivary amylase, chlorine, bicarbonate among others, we find the parotids, sublingual and submaxillary. The digestive system is very complex and I think one of the most important. There is so much information that is difficult to join all.
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