Digestive system general structure:
- What is the function of digestive system?
- The function of digestive system is to obtain molecules from the ingested food which is necessary for the maintenance, growth and energy needs of the body
- What happens during digestion? or what is digestion?
- The digestion is the process where proteins, complex carbohydrates, nucleic acids and fats are broken down into small molecules which can be easily absorbed by the small intestine
- What are the four main layers of digestive tract?
- From within (lumen) outwards
- Mucosa (mucous membrane)
- Submucosa
- Muscularis externa
- Serosa or adventitia
- What are the layers of mucosa?
- From lumen outwards
- Epithelial lining
- Lamina propria
- Muscularis mucosae
- What are the different types of epithelial lining observed in the digestive tract?
- Stratified squamous non-keratinized epithelium (mouth, esophagus)
- Simple columnar epithelium (stomach, intestine)
- Tall columnar ciliated epithelium (gall bladder)
- What are the components of lamina propria?
- Loose connective tissue
- Blood vessels
- Lymphatics
- Lymphocytes
- Smooth muscle cells
- Glands
- What is muscularis mucosae?
- Muscularis mucosae is a thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria
- What are the components of submucosa?
- Dense connective tissue
- larger blood vessels
- Glands and lymphoid tissue in few parts of the tract
- Submucosal (Meissner's) plexus of autonomic nerves
- What are the components of muscularis externa?
- Inner circular smooth muscle layer
- Outer longitudinal smooth muscle layer
- Between two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
- What is serosa or adventitia? Difference between serosa and adventitia
- Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by simple squamous epithelium (mesothelium)
- Adventitia- loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent
- What is mesothelium?
- It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
- What is the function of Meissner's plexus?
- Meissner’s plexus regulates the configuration of the luminal surface, controls glandularsecretions, alters electrolyte and water transport and regulates local blood flow
- What is the function of Myenteric plexus?
- Myenteric plexus supplies the GIT and controls the gastric motility
