What is the digestive system?
The digestive system is a set of organs and structures responsible for processing and absorbing foods, as well as eliminating parts of undigested food (residues).
The digestive system is formed by the mouth, the epiglottis, the pharynx, the esophagus, the stomach, the liver, the pancreas, the small intestine and the large intestine.
The mouth
The term “mouth” refers to the opening of the digestive tract and to the oral cavity at the same opening. It is supported by a skeletal arch composed from the maxillary (upper) and mandibular (lower) divisions, each of which is equipped with teeth. The lips mark the transition from mucous membrane to skin, which covers most of the body. In addition to its primary role as the beginning of the digestive system, the mouth also plays a role in phonation and respiratory functions, as well as a forum to taste perception.
The epiglottis
The epiglottis is a flap of elastic cartilage that is covered with a mucous membrane and located at the root of the tongue. The primary function of the epiglottis is to prevent chewed food and saliva from entering the trachea. For this reason, the epiglottis folds backwards during swallowing movements as to cover the opening of the larynx so that food and liquid are directed to the esophagus. After swallowing, the epiglottis returns to its original position and the opening of the larynx closes.
The pharynx
The pharynx is a channel that connects the throat with the esophagus. The mucosal lining represents the first portion of the digestive tract, which receives food bolus from the mouth through swallowing (upper airway portion). The air coming through the nasal passageway enters the pharynx, which in turn directs it toward the larynx. Pharynx flows through the food airways and then continues separately into the esophagus and larynx.
The esophagus
The esophagus is the portion of the alimentary canal that connects the pharynx to the stomach. Chewed food is partially digested by enzymes in saliva and then directed through this tube, from the mouth to the stomach. The bolus passage is facilitated by the contraction of muscle in the wall of the esophagus.
The stomach
The stomach is the organ that receives food from the esophagus, after it has been chewed and swallowed through the mouth. It is where the digestive process begins, which is made possible by digestive enzymes from the regular contraction of the stomach itself. The food is then passed through the intestines, where the digestive process continues, allowing nutrients to be absorbed from the foods ingested. From an anatomical point of view, it can be considered an enlargement, as a pouch form of the digestive tract. The stomach is in fact directly connected to both the esophagus (from which it receives the food that passes through a structure called the lower esophageal sphincter) as well as the small intestine, which separates it from the pyloric sphincter , a muscular valve whose opening and closing regulates the emptying of the stomach.
The liver
The liver is the largest gland in the human body, essential for metabolism. It is connected to the digestive system and performs many functions not only helpful to the digestion of food, but also to the defense mechanism of the body and the elimination of toxic substances. The liver encourages the transformation of food absorbed by the emulsion of fat, the synthesis of glucose, cholesterol and triglycerides, as well as control of the protein metabolism. Also stored in the liver are glucose, vitamin B12, iron and cooper.
The pancreas
The pancreas is a gland that takes the shape of an elongated cone and is a part of the digestive system. It is involved in endocrine secretion (a process that entails secretion of products, hormones, directly into the bloodstream), as well as exocrine secretion (a process in which products are placed in a natural cavity in the body or released outside). Almost horizontally positioned, the pancreas is located in the upper abdomen, and transversely behind the stomach, at the level of the first two lumbar vertebrae.
The exocrine secretion, essential for the digestive process of food consumed, is carried out by small structures known as glandular acini, which are secreted into the intestine and pour through the Wirsung duct.The final product in the exocrine secretion is the pancreatic juice, which is a liquid that is formed by a set of enzymes (lipase, amylase, etc.) essential for digestion.
The small intestine
The small intestine is the longest part of the digestive system, about 7 meters long. It is a muscular tube that is divided into three portions: the duodenum, jejunum and ileum. The small intestine flows into the large intestine through the ileocecal valve. The mucous membrane that covers the interior walls is covered by the intestinal villi (responsible for the absorption of nutrients introduced through food) and the circular folds, whose presence serves to expand the surface of the small intestine in order to better carry out tasks regarding digestion and absorption of nutrients.
The large intestine
The large intestine, also called the colon or the large bowel, is the final part of the intestines and in general, of the 'digestive tract. It is about 1.5 meters long and extends from the ileocecal valve (or valve Bauhin) to the anus. The function of the large intestine is to terminate the digestive process by absorption, fermentation, and evacuation of ingested foods.
What function does the digestive system serve?
The primary function of the digestive system is linked to the assumption, processing, and absorption of food, as well as removal of undigested food (residues).
