Grand Tour of the Alimentary Canal Flashcards
What are the functions of the digestive system
Digestion, secretion, absorption, motility
Function of mouth
Foodstuffs broken down by chewing; saliva added as lubricant
Function of oesophagus
Conduit between mouth and stomach
Function of stomach
Digestion of proteins; foodstuffs reduced to liquid form; storage; sterilisation
Function of pancreas
Digestive enzymes for digestion of fats, carbohydrates and proteins
Function of liver
Bile salts for digestion/absorption of fats in small intestine
Function of gallbladder
Stores and concentrates bile
Function of small intestine
Final stages of chemical digestion and nutrient absorption
Function of the large intestine
Water absorption, bacterial fermentation and formation of faeces
What are the 4 distinctive layers
Mucosa (epithelium, lamina propria, muscularis mucosa)
submucosa, muscularis externa, serosa/ adventitia
Where is serosa found?
Found in organs inside the peritoneal cavity. Serosa surrounds stomach, small intestine and large intestine.
Where is the adventitia found?
Found in organs outside the peritoneal cavity. Adventitia attaches oesophagus and rectum to surrounding structures.
Where is stratified squamous epithelium found in the GI tract?
mouth, oesophagus, anal canal
Where is simple columnar epithelium found?
stomach, small intestine, large intestine
What is the function of epithelium?
barrier separating the lumen fo the alimentary canal from the body . synthesis and secretion of digestive enzymes, hormones and mucus. absorbs products of digestion
Define lamina propria
Loose connective tissue (glands, blood/ lymph vessels)
What is muscualris mucosae
thin smooth muscle layer
What is the submucosa?
thick, irregular connective tissue.
What does the submucosa contain?
Contains neurones, blood vessels, lymphatic vessels. neurons form extensive network Meissener’s plexus. submucosal glands in oesophagus and duodenum
What is serosa/ adventitia?
connective tissue outer layer of the alimentary canal
What is the muscularis externa?
Two concentric thick layers of smooth muscle.
Inner layer = circular muscle to constrict lumen
Outer layer = longitudinal muscle to shorten tube.
Function of the muscularis externa?
produce motility (peristalsis and segmentation) Myenteric (Auerbac's) plexus between circular and longitudinal muscle.
What is the enteric nervous system
Submucosal and myenteric plexus = enteric nervous system. allows independent control of gut function.
Autonomic control of the gut
Long (parasympathetic) and short (ENS) reflexes
Parasympathetic nervous control of the gut?
Vagus nerve. except salivation (facial and glossopharyngeal)
stimulates increased secretion and motility
Sympathetic nervous control of the gut
Splanchnic nerve.
inhibitory (except salivation)
decrease secretion and motility
What are the organs supplied by the celiac trunk?
stomach, 2nd part of the duodenum pancreas and liver
What organs are supplied by the superior mesenteric artery?
small intestine, caecum, ascending colon, transverse colon
What organs are supplied by the inferior mesenteric artery?
descending colon, sigmoid colon, rectum
What is the general venous drainage of the GI tract?
hepatic portal vein -> hepatic vein -> inferior vena cava
What is the venous drainage of the stomach
Gastric veins
What is the venous drainage of the pancreas?
splenic vein
Which organs are drained by the superior mesenteric vein?
small intestine, caecum, ascending colon, transverse colon
Which organs are drained by the inferior mesenteric vein?
descending colon, sigmoid colon, rectum
Difference between hepatic artery, hepatic portal vein, hepatic vein
Hepatic artery = carries oxygenated blood from the heart to liver
Hepatic portal vein = carries deoxygenated blood from the GI tract to the liver
Hepatic vein = carries deoxygenated blood from the liver to the heart.
