Grand Tour of Alimentary Canal Flashcards
What are the 4 main functions of the digestive system?
Digestion
Secretion
Absorption
Motility
What happens in the mouth at the start of the digestion process?
Food is broken down by chewing
Saliva is added as a lubricant
What is the oesophagus?
Conduit between mouth and stomach
What happens in the stomach?
Digestion of proteins
Food –> liquid form
Storage
Sterilisation
What do enzymes from the pancreas digest?
Fats
Carbohydrates
Proteins
What are found in the liver for digestion/absorption of fats in the small intestine?
Bile salts
What does the gallbladder do?
Stores and concentrates bile
What happens in the small intestine?
Final stages of chemical digestion and nutrient absorption
What happens in the large intestine?
Water absorption
Bacterial fermentation
Formation of faeces
What are the 4 distinctive layers of the alimentary canal?
Mucosa (epithelium, lamina propria, muscularis mucosae)
Submucosa
Muscularis externa
Serosa/adventitia
What type of epithelium is found in the mouth, oesophagus and anal canal?
Stratified squamous
What type of epithelium is found in the stomach, small/large intestine?
Simple columnar
What is the function of epithelium in the mucosa?
Synthesis and secretion of digestive enzymes, hormones, mucus
Absorbs products of digestion
Barrier separating lumen of alimentary canal from body
What is the lamina propria?
Loose connective tissue (glands, blood/lymph vessels)
What is the muscularis mucosae?
Thin smooth muscle layer
What is the submucosa?
Thick, irregular connectie tissue that supports the mucosa
What does the submucosa contain?
Neurones, blood vessels, lymphatic vessels
What do neurones form in the submucosa?
Submucosal (Meissner’s) plexus (parasympathetic)
Where are the submucosal glands?
Oesophagus and duodenum
What is the serosa/adventitia?
Connective tissue outer layer of alimentary canal
What is the difference between serosa and adventitia layer?
Adventitia = outside peritoneal cavity, attaches oesophagus and rectum to surrounding structures Serosa = inside peritoneal cavity, surrounds stomach, small intestine and large intestine
What is the function of the inner layer of muscularis externa?
Circular muscle that constricts lumen
What is the function of the outer layer of muscularis externa?
Longitudinal muscle that shortens tube
What is the purpose of the 2 concentric layers of smooth muscle of the muscularis externa?
To produce motility for peristalsis and segmentation
What is the name of the plexus between the circular and longitudinal muscle of the muscularis externa?
Myenteric (Auerbach’s) plexus
What does the combination of submucosal and myenteric plexuses form? + purpose
Enteric nervous system (ENS) which has independent control of gut function
What supplies autonomic control on the alimentary system?
Long (parasympathetic) and short (ENS) reflexes
What supplies parasympathetic control on the alimentary system? + effect
Vagus nerve
Except salivation which is controlled by facial (VII) and glossopharyngeal nerves (IX)
Stimulatory (increase in secretion and motility)
What supplies sympathetic control on the alimentary system? + effect
Splanchnic nerve
Inhibitory (except salivation) = causes decrease in secretion and motility
What organs does the celiac trunk supply?
Stomach
Small intestine
Pancreas
Liver
What organs does the superior mesenteric artery supply?
Small intestine
Caecum
Ascending colon
Transverse colon
What organs does the inferior mesenteric artery?
Descending colon
Sigmoid colon
Rectum
Where does venous drainage from the stomach go to?
Gastric veins
Where does venous drainage from the pancreas go to?
Splenic vein
What structures drain into the superior mesenteric vein?
Small intestine
Caecum
Ascending colon
Descending colon
What structures drain into the inferior mesenteric vein?
Descending colon
Sigmoid colon
Rectum
What veins drain into the hepatic portal vein?
Gastric veins
Splenic vein
Superior mesenteric vein
Inferior mesenteric vein
Where does the hepatic portal vein drain into?
Hepatic vein
Where does the hepatic vein drain into?
Inferior vena cava
