Grand Tour of the Alimentary Canal Flashcards
What are the four main functions of the Digestive System?
Digestion - Materials broken down
Secretion - Entities going into circulation
Absorption - Entities being carried across the GI Tract
Motility - Entities moving down the canal towards the anus
What goes into the oral cavity to aid digestion?
Saliva
What acts as a valve for the oesophagus from the mouth?
Upper Oesophageal Sphincter made of a thickened muscular ring?
What are the functions of the Stomach?
Protein digestion
Foodstuff reduced to liquid form
Storage
Sterilisation
Is secretion heavy in the stomach and why?
Yes - To help form a slurry
What is Dumping Syndrome?
When food bypasses the stomach and enters the small intestine undigested
What is the main role of the Pancreas?
To produce digestive enzymes for fats, carbohydrates and proteins
What does the Liver do?
Produces Bile salts for digestion
Absorption of fats in the Small Intestine
What does the Gallbladder do?
Stores and concentrates bile
What in the role of the Small Intestine?
Final stages of chemical digestion and nutrient absoprtion
What are the main functions of the Large Intestine?
Water absorption
Bacterial Fermentation
Faeces formation
What are the four layers of the Alimentary canal wall?
Mucosa - Inner layer (Epithelium, Lamina Propria & Muscularis Mucosae)
Submucosa
Muscularis Externa
Serous/Adventitia
What type of epithelium line the mouth, oesophagus and anal canal?
Stratified squamous
What type of epithelium line the stomach and intestine?
Simple columnar
What is the lamina propria made of?
loose connective tissue - Glands & Blood/Lymph vessels
What is the muscularis mucosae made of?
Thin smooth muscle layer
What is the submucosa made of and where are they found?
Thick, irregular connective tissue that supports the mucosa containing blood vessels, lymphatic vessels and neurones
Found in the oesophagus and duodenum
What are the two layers of the muscularis externa made of?
Inner layer is circular and constricts the lumen
Outer layer is longitudinal and shortens the tube
Can Peristalsis and Segmentation occur at the same time?
No
What has independent control of gut function and what it is made up of?
Enteric Nervous System (ENS) - Submucosal and Myenteric plexuses
What does the Serosa/Adventitia attach the oesophagus and rectum to?
Surrounding structures
What does the serosa surround in the peritoneum?
Stomach and the entirety of the intestine
What nerve carries parasympathetic signals and are these inhibitory/stimulatory?
Vague nerve
Stimulatory
Increase secretion and motility
What nerve carries sympathetic signals and are these inhibitory/stimulatory?
Splanchic nerve
Inhibitory
Decreased secretion and motility
What are the main arteries of the GI Tract and where do they branch off?
Coeliac trunk - T12
Superior mesenteric artery - L1
Inferior mesenteric artery - L3
What organs does the Coeliac trunk supply?
Stomach Small intestine Pancreas Liver *FOREGUT*
What organs does the Superior mesenteric artery supply?
Small intestine
Caecum
Ascending & Transverse colon
MIDGUT
What organs does the Inferior mesenteric artery supply?
Descending colon
Sigmoid Colon
Rectum
HINDGUT
What veins does the stomach drain into?
Gastric veins
What veins does the pancreas drain into?
Splenic veins
What organs drain into the Superior mesenteric vein?
Small intestine
Caecum
Ascending & Transverse colon
MIDGUT
What organs drain into the Inferior mesenteric vein?
Descending colon
Sigmoid Colon
Rectum
HINDGUT
What is the order of drainage of veins in the GI Tract?
All afore mentioned veins to hepatic portal vein to hepatic vein to IVC
