Introduction to the Alimentary Canal Flashcards
What are the functions of the digestive system?
Digestion
Secretion
Absorption
Motility
What are the 4 layers of the alimentary canal?
Mucosa
Submucosa
Muscularis Externa
Serosa/Adventitia
What are the 3 layers of the mucosa?
Epithelium
Lamina propria
Muscular mucosae
What type of cells make up the epithelium of the mouth, oesophagus and anal canal?
Stratified squamous
What type of cells make up the epithelium of the stomach, small and large intestine?
Simple columnar
What does the epithelium do?
Absorbs products of digestion
What type of tissue is lamina propria?
Loose, connective tissue
What type of muscle is the muscularis mucosae?
Smooth muscle
What type of tissue is the submucosa?
Thick, irregular connective tissue
What does the submucosa do?
Supports mucosa
Where do you find submucosal glands?
Oesophagus
Duodenum
What type of tissue is serosa/adventitia?
Connective tissue
What is the difference between serosa and adventitia?
Serosa is inside the peritoneal cavity (stomach, small and large intestine)
Adventitia is outside the peritoneal cavity (oesophagus and rectum)
What are the 2 layers of the muscularis externa?
Circular muscle (inner) Longitudinal muscle (outer)
What is the function of the muscularis externa?
Produces motility for peristalsis and segmentation
Where is the myenteric plexus (Auerbach’s) located?
Between the circular and longitudinal layers
What comprises the enteric nervous system?
Myenteric plexus and Submucosal plexus
What is the parasympathetic innervation of the alimentary canal?
Vagus nerve
What is the sympathetic innervation of the alimentary canal?
Splanchnic nerve
What is the effect of parasympathetic innervation?
Stimulatory (increases secretion and motility)
What is the effect of sympathetic innervation?
Inhibitory (decrease secretion and motility)
What is the main arterial supply of the GI tract?
Celiac trunk
Superior mesenteric artery
Inferior mesenteric artery
What is the venous drainage of the GI tract?
Gastric to hepatic portal to hepatic to IVC
Splenic to hepatic portal to hepatic to IVC
Sup/Inf mesenteric to hepatic portal to hepatic to IVC