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The Digestive System and associated membranes


image result for The Digestive System The function of the digestive system is to digest and absorb food. It consists of  a tubular gastrointestinal tract and accessory organs that aid in digestion and absorption.
All organisms require food to sustain life. The cells of the body require nutrients for the chemical reactions of enzyme synthesis, cell division, growth and repair and also for the production of heat energy. Most of the food we eat requires considerable processing before it can be used by the cells. It must be broken down mechanically and chemically before it is transported by the blood to the cells.
The activities that are performed by the digestive system include the following activities:
1.    Ingestion: the taking of food into the mouth
2.    Mastication: chewing food which pulverizes it and mixes it with saliva
3.    Deglutination: Swallowing; moving food from the mouth to the pharynx and into the esophagus.
4.    Digestion: The mechanical and chemical breakdown of food to prepare it for absorption.
5.Absorption: the passage molecules of food through the mucous membrane of the small intestine and into the blood and lymph for distribution to the cells.
6.Peristalsis: the rhythmic wavelike contractions of the smooth muscle of the intestines that move food through the GI tract.
7. Defecation: the discharge of indigestible wastes (feces) from the GI tract.
Anatomically and functionally the digestive system can be divided into a tubular gastrointestinal (GI) tract and accessory digestive organs.  The GI tract which extends from the mouth to the anus is a continuous tube approximately 30 feet (9m) long. It goes through the thoracic cavity and enters the abdominal cavity through the diaphragm.



The organs of the digestive system include the oral cavity (mouth), pharynx, esophagus, stomach, small intestine and large intestine. The accessory organs include teeth, salivary glands, liver, gall bladder and pancreas.
It usually takes about 24-48 hours for food to travel the length of the GI tract. Food travels in an assembly line manner through the tract where it is broken down to the molecular level and transported to the cells. Each region of the GI tract has a specific function in the process 

 Membranes of the Abdominal Cavity

Most of the digestive organs are located in the abdominal cavity. These organs are covered by serous membranes that line the cavity and cover the organs within. Serous membranes secrete a lubricating serous fluid that continuously moistens the organs. The parietal membrane lines the wall of the abdominal cavity and the visceral membrane covers the internal organs. 
The membrane that lines the wall of the abdominal cavity is called the  parietal peritoneum. It comes together to form a double layered peritoneal fold called the mesentery

The mesentery supports the GI tract and at the same time allows the small intestine freedom for peristaltic contractions. It also provides a structure for the passage of blood vessels and nerves. The peritoneal membrane continues around the intestinal organs as the visceral peritoneum. The peritoneal cavity is the space between the parietal and visceral portions of the peritoneum. Certain organs lie posterior to the peritoneal cavity and are said to be retroperitoneal. These organs include  most of the pancreas, the kidneys, adrenal glands and portions of the duode num and colon as well as the abdominal aorta


Peritonitis is an inflammation of the peritoneum usually caused by an infection. This can occur due to trauma, rupture of an organ, an ectopic pregnancy or post operative infection. It is a serious life threatening situation. Treatment usually involves massive doses of antibiotics as well as insertion of a tube to drain excess fluid which accumulates.

Extensions of the parietal peritoneum serve to suspend or anchor organs within the peritoneal cavity. The falciform ligament attaches the  diaphragm and the anterior abdominal wall to  the liver. The greater omentum extends from the stomach to the transverse colon forming an apron like covering over most of the  small intestine. 

Function of the omentum includes storage of fat, cushioning visceral organs, supporting lymph nodes and protection against infection. in cases of infection such as appendicitis the greater omentum may actually compartmentalize the infection, sealing it off from the rest of the peritoneal cavity.  The lesser omentum passes from the lesser curve of the stomach and the upper duodenum to the inferior surface of the liver
The Digestive System and associated membranes The Digestive System and associated membranes Reviewed by gafacom on June 03, 2019 Rating: 5

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