esophagus in digestive system Flashcards
Q: What is the function of the esophagus?
A: The esophagus is a passageway that conducts food from the pharynx to the stomach by peristalsis.
Q: How long is the esophagus?
A: The esophagus is about 25 cm (10 inches) long.
What are the four tissue layers (tunics) of the alimentary canal organs from the esophagus to the large intestine?
A: The four tissue layers are the mucosa, submucosa, muscularis externa, and serosa.
Q: What is the mucosa layer?
A: The mucosa is the innermost layer, a moist mucous membrane that lines the lumen of the organ.
Q: What does the submucosa contain?
A: The submucosa contains soft connective tissue, blood vessels, nerve endings, mucosa-associated lymphoid tissue (MALT), and lymphatic vessels.
Blood vessels: These supply nutrients and oxygen to the tissues of the digestive tract and help remove waste products.
Lymphatic vessels: These are part of the immune system, helping to defend against infections.
Nerve plexuses: These are part of the enteric nervous system, which helps regulate digestive functions like peristalsis and enzyme secretion.
Connective tissue: This provides support and structure to the digestive tract.
Q: What is the muscularis externa?
A: The muscularis externa is a muscle layer consisting of an inner circular layer and an outer longitudinal layer of smooth muscle cells.
The muscularis externa is responsible for the motility of the digestive tract, ensuring food is moved through the system efficiently. It consists of two smooth muscle layers (inner circular and outer longitudinal), and works with the myenteric plexus to control muscle contractions for peristalsis and segmentation.
What is the serosa?
: The serosa is the outermost layer of the wall, made up of the visceral peritoneum, a serous membrane that produces fluid and is continuous with the parietal peritoneum.
Visceral Peritoneum: This is the part of the serosa that directly covers the digestive organs (like the stomach and intestines). It’s a serous membrane, meaning it secretes a small amount of serous fluid to reduce friction as the organs move during digestion and peristalsis.
Continuous with the Parietal Peritoneum: The parietal peritoneum lines the abdominal wall, while the visceral peritoneum lines the organs. The two layers are continuous, meaning the visceral layer covers the organs, and the parietal layer lines the walls of the abdominal cavity. The space between these two layers is called the peritoneal cavity, which contains fluid to allow smooth movement of the organs.
Q: What is a mesentery
A: A mesentery is formed when two layers of peritoneum(sereous membrane)are fused together, creating routes for nerves, blood vessels, and lymphatic vessels. It also anchors digestive organs and stores fat.
Q: What is peritonitis?
A: Peritonitis is an infection of the peritoneum, the membrane that lines the abdominal cavity. Bacterial infection: This is the most common cause, often from a ruptured appendix, ulcers, or a hole in the intestines. It can also occur due to infection from conditions like diverticulitis or Crohn’s disease.
Q: How does the body respond to peritonitis?
: The peritoneal membranes tend to stick together around the infection site, helping to seal off and localize the infection in the layer muscles
What is the purpose of the peritoneal membranes sticking together during peritonitis?
This response helps provide time for macrophages in the lymphatic tissue to mount an attack on the infection.
What are the two important intrinsic nerve plexuses in the alimentary canal wall?
A: The two important intrinsic nerve plexuses are the submucosal nerve plexus and the myenteric nerve plexus.
Q: What is the function of the intrinsic nerve plexuses in the alimentary canal?
A: The intrinsic nerve plexuses help regulate the mobility and secretory activity of GI tract organs.
Q: What system are the submucosal and myenteric nerve plexuses part of?
: They are part of the autonomic nervous system.
The parts of esophagus
Cerviacal part,thoriac part,abdominal part
Mucosa layers
The innermost layer of the digestive tract, made up of three components:
Surface Epithelium: In the esophagus, this is stratified squamous epithelium, which helps protect against mechanical stress and abrasion from food. In other parts of the digestive tract (like the stomach, small intestine, and large intestine), the epithelium is usually simple columnar epithelium, which is specialized for absorption and secretion.
Lamina Propria: A layer of loose connective tissue that supports the epithelium and contains blood vessels, lymphatic vessels, and immune cells. It provides nourishment and plays a role in immune defense.
Muscularis Mucosae: A thin layer of smooth muscle that helps move the mucosa, which aids in increasing the surface area for absorption and secretion.
The mucosa is moist because of the mucus produced by epithelial cells and glands in the underlying layers, helping with lubrication and protection.
So, in summary, the mucosa forms the moist, protective lining of the digestive tract, with the type of epithelium varying depending on the location and function. In the esophagus, stratified squamous epithelium is key for protection, while in areas like the intestines, simple columnar epithelium aids in absorption and secretion.
