Grand tour of the alimentary canal Flashcards
What are the 4 main functions of the digestive system?
digestion, secretion, absorption and motility
What are the 2 requirements for digestion?
Aqueous environment and enzymes
What organ does ALL of the gut circulation pass through?
Liver
Name the 3 pairs of salivary glands
Parotid, submandibular and sublingual
What is the lubricant for breakdown of food?
Saliva
What is the length of the alimentary canal from oesophagus to rectum?
8m
What are the 4 layers found in the alimentary canal wall?
Mucosa, submucosa, muscularis externa and adventitia/serosa
What are the 3 layers of the mucosa?
Epithelium, lamina propria and muscularic mucosae
What is the lamina propria?
Connective tissue fo rsupport
Explain what the difference is between addventita and serosa
Advetitia is the outermost layer of the canal wall located outside the peritoneal cavity ( above the diaphragm) whereas serosa is the exact same but found inside the peritoneal cavity
What is the muscularis externa important for?
Motility
Where are the 2 locations of submucosal glands?
Oesophagus and duodenum
What do the submucosal glands in the 2 locations secrete?
Oesophagus = mucus duodenum = bicarbonate
What are the 2 muscular layers forming the muscularis externa?
Circumferential and longitudinal layer
What do the circumferential and longitudinal muscle layers control?
Circumferential = diameter Longitudinal = length of the tube
What plexus is found between the submucosa and circular muscle layer?
Submucosal plexus
What plexus is found between the 2 muscular layers?
Myenteric plexus
What do the submucosal and myenteric plexus form?
The enteric nervous system (ENS)
What kind of epithelium lines the mouth,oesophagus and anal canal? Why?
Stratified squamous - for solid material
What kind of epithelium lines the stomach and intestines? Why?
Simple columnar - for diffusion
What 3 processes occur in the epithelium?
Secretion, absorption and synthesis
What structures are found in the lamina propria?
Lymph and blood vessels, glands
What does the submucosa support?
Mucosa and the neurones and blood+lymphatic vessels
What do the neurons in the submucosa form?
Submucosal plexus
What does the adventitia attach the oesophagus and rectum to?
Surrounding structures
What does the serosa surround?
Stomach and intestines
What nerve controls parasympathetic gut function? What cranial nerve is this?
Vagus - 10
What nerves control parasympathetic salivation? Why?
Facial(7) and glossopharyngeal (4) as vagus does not innervate the head and neck
What nerve controls sympathetic innervation of gut function?
Splanchnic
Explain sympathetic and parasympathetic in terms of inhibitory and stimulatory
Parasympathetic - stimulatory ALWAYS
sympathetic - inhibitory EXCEPT salivation
What 3 arteries does the celiac trunk give off?
Splenic, common hepatic and left gastric
What is the arterial supply of the gut?
Celiac trunk, superior and inferior mesenteric arteries
Give 1 structure that each of the 3 gut arteries supplies
Celiac - stomach superior - ascending colon
inferior - sigmoid colon
What vein does the stomach drain into?
Gastric veins
What vein does the pancreas drain into?
Splenic veins
What 4 veins drain into the hepatic portal vein?
Gastric, splenic, inf. and sup. mesenteric veins
Explain the difference between the hepatic portal and hepatic vein
The hepatic portal vein drains to the liver and the hepatic vein is from the liver draining into the IVC
Ultimately what vein do all the veins drain into?
The IVC
What mixes with the hepatic portal vein in the liver?
Hepatic artery
