What are the secretions of the inner lining of the stomach. Answer in brief
Answers
Answer:
What are the secretions of the inner lining of the stomach. Answer in brief
Explanation:
The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital digestive organ. In the digestive system the stomach is involved in the second phase of digestion, following chewing. It performs a chemical breakdown due to enzymes and hydrochloric acid.
In humans and many other animals, the stomach is located between the oesophagus and the small intestine. It secretes digestive enzymes and gastric acid to aid in food digestion. The pyloric sphincter controls the passage of partially digested food (chyme) from the stomach into the duodenum where peristalsis takes over to move this through the rest of the intestines.
Structure
In humans, the stomach lies between the oesophagus and the duodenum (the first part of the small intestine). It is in the left upper part of the abdominal cavity. The top of the stomach lies against the diaphragm. Lying behind the stomach is the pancreas. A large double fold of visceral peritoneum called the greater omentum hangs down from the greater curvature of the stomach. Two sphincters keep the contents of the stomach contained; the lower oesophageal sphincter (found in the cardiac region), at the junction of the oesophagus and stomach, and the pyloric sphincter at the junction of the stomach with the duodenum.
The stomach is surrounded by parasympathetic (stimulant) and sympathetic (inhibitor) plexuses (networks of blood vessels and nerves in the anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretory activity of the stomach and the motor (motion) activity of its muscles.
Because it is a distensible organ, it normally expands to hold about one litre of food.[3] The stomach of a newborn human baby will only be able to retain about 30 millilitres. The maximum stomach volume in adults is between 2 and 4 litres.[4][5]
Sections
1. Body of stomach 2. Fundus 3. Anterior wall 4. Greater curvature 5. Lesser curvature 6. Cardia 9. Pyloric sphincter 10. Pyloric antrum 11. Pyloric canal 12. Angular incisure 13. Gastric canal 14. Rugae[6]
In classical anatomy the human stomach is divided into four sections, beginning at the cardia.[7]
The cardia is where the contents of the esophagus empty into the stomach. [8]
The fundus (from Latin, meaning 'bottom') is formed in the upper curved part.
The body is the main, central region of the stomach.
The pylorus (from Greek, meaning 'gatekeeper') is the lower section of the stomach that empties contents into the duodenum.
The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower oesophageal sphincter.[8] Recent research has shown that the cardia is not an anatomically distinct region of the stomach but a region of the oesophageal lining damaged by reflux.
Anatomical proximity
The stomach bed refers to the structures upon which the stomach rests in mammals.[10][11] These include the pancreas, spleen, left kidney, left suprarenal gland, transverse colon and its mesocolon, and the diaphragm. The term was introduced around 1896 by Philip Polson of the Catholic University School of Medicine, Dublin. However this was brought into disrepute by surgeon anatomist J Massey.Anatomical proximity
The stomach bed refers to the structures upon which the stomach rests in mammals.[10][11] These include the pancreas, spleen, left kidney, left suprarenal gland, transverse colon and its mesocolon, and the diaphragm. The term was introduced around 1896 by Philip Polson of the Catholic University School of Medicine, Dublin. However this was brought into disrepute by surgeon anatomist J Massey.[12][13][14]
Microanatomy
Wall
The gastrointestinal wall of the human stomach.
Main article: Gastrointestinal wall
Like the other parts of the gastrointestinal tract, the human stomach walls consist of a mucosa, submucosa, muscularis externa, subserosa and serosa.[16]
The inner part of the lining of the stomach, the gastric mucosa, consists of an outer layer of column-shaped cells, a lamina propria, and a thin layer of smooth muscle called the muscularis mucosa. Beneath the mucosa lies the submucosa, consisting of fibrous connective tissue.[citation needed] Meissner's plexus is in this layer.[17]