Week One (Part One) Flashcards
General Structure of GI Wall
Outer to Inner:
Peritoneum Serosa Longitudal Layer of Smooth Muscle Circular Layer of Smooth Muscle Submucosa Mucosa
General Structure of GI Wall
Submucosa (Define):
Nerves, blood vessels, digestive glands
Upper GI Tract
Structure (General):
Mouth
Esophagus
Stomach
Upper GI Tract
Mouth (Purpose):
Used for chewing, mixing, and swallowing
Upper GI Tract
Mouth (Enzyme):
Saliva. Used for protection, lubrication, and digestion.
Amylase is also present in saliva, which helps to break down starch.
Upper GI Tract
Esophagus (Purpose):
Moving food down the stomach by peristalsis motion; connects mouth to the stomach.
Upper GI Tract
Esophagus (Structure):
Upper and lower sphincter, controlled by the Cranial Nerve X and gastrin.
Upper GI Tract
Stomach (Purpose):
Used for storage, digesting (peristaltic mixing, churning, moving secretions.
Upper GI Tract
Stomach (Structure):
Connected to esophagus at cardia sphincter and to the small intestine at the pyloric sphincter.
Composed of fundus, body, antrum, and pylorus (in descending order).
Upper GI Tract
Stomach (Secretions):
Mucus, HCL, and pepsinogen. Stimulated by the parasympathetic nervous system, gastrin, and histamine
Upper GI Tract
Digestion:
Little to no absorption occurs in the Upper GI Tract except for the absorption of alcohol.
Middle GI Tract
Structure (General):
Duodenum
Jejunum
Ileum
Middle GI Tract
Structure (Purpose):
Digestion, absorption, secretion of enzyme, moving. Most digestion and absorption happens here.
Produce secretions of serous (Lieberkuhn), peptidase, disaccharidase
Middle GI Tract
Duodenum (Purpose):
Receive secretion from liver and pancreas.
Secrete mucus, cholecystokinin, gastrin, and secretin
Middle GI Tract
Jejunum (Purpose):
Main site of absorption.
Secretes mucus.
Middle GI Tract
Ileum (Purpose):
Connected to the cecum by the ileocecal valve.
Lower GI Tract
Structure (General):
Cecum Ascending Colon Transverse Colon Descending Colon Sigmoid Colon
Lower GI Tract
Purpose (General):
Moving stool by haustration and propulsion.
Defecation.
Absorption of water and electrolytes (minor).
Lower GI Tract
Defecation and the Sphincter:
Internal sphincter is controlled by the sacral spinal cord (and the automatic nervous system).
External sphincter is controlled by the cerebral cortex (and the conscious nervous system).
