Digestive System (GI Tract) Flashcards
Describe the basic anatomy of the GI Tract
Mouth, pharynx, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (cecum, ascending colon, transverse, descending, sigmoid, rectum, anus)
What are the accessory digestive organs?
Teeth/Tongue, Salivary glands, Gallbladder, Liver, Pancreas
What is the purpose of the accessory digestive organs?
Breakdown of food
What are the 4 main layers of the GI Tract?
Mucosa, submucosa, muscularis externa, serosa
What does the mucosa subdivide into?
Mucous membrane, lamina propria, muscularis mucosae
Describe the mucosa
Lines lumen of GI tract, an absorptive/secretory layer
Describe the submucosa
Thick, vascular layer of connective tissue
Describe the muscularis externa
For peristalsis/segmentation contractions
Layer of smooth muscle that contract to move food down via digestive enzymes
What does the muscularis externa subdivide into?
Circular muscle (inner) Longitudinal muscle (outer)
Describe the serosa
Connective tissue/squamous epithelium
Continues along with mesentary/visceral peritoneum
Describe the subdivisions of the enteric nervous system
Submucosal plexus
Myenteric plexus
Describe the submucosal plexus
Nerve supply to muscularis mucosae, regulates GI blood
Describe the myenteric plexus and where it’s found
Major nerve supply to GI tract, controls motility
Found between muscles of muscularis externa
What are the 4 major functions of the GI Tract?
Motility, Secretion, Digestion, Absorption
Describe the propulsion system (swallowing)
Epiglottis closes, upper oesophageal sphincter relaxes/opens, bolus moves down by peristalsis, upper sphincter contracts/closes, lower oesophageal sphincter opens, circular smooth muscle contracts behind and relaxes in front
What does the bolus activate?
Excitatory and inhibitory neuronal circuits in enteric NS to propel food along gut
