GI System Physiology Flashcards
What are 3 constrictions of oesophagus
Cervical
Thoracic
Diaphragmatic
Where does oesophagus pass through at diaphragm
Oesophageal hiatus
Acts as sphincter
How is oesophagus peritonised
Retroperitoneal
What part of stomach does oesophagus enter
Cardial orifice
What type of muscle is the oesophagus
Striated at top
Becomes smooth
What is the arterial supply
Left gastric - oesophageal branches
Celiac trunk
Left inferior phrenic
What is the venous drainage
Left gastric -> portal venous
Oesophageal -> azgous
What is the lymphatic drainage of the oesophagus
Left gastric
Celiac
What innervates the oesophagus
Vagus nere
Thoracic sympathetic
Splanchnic nerve
What are the parts of the stomach
Cardia - surrounds cardiac orifice (no sphincter)
Fundus - filled with gas at top related to left dome of diaphragm
Body
Pylorus - pyloric sphincter controlling discharge into duodenum
What is behind the shorter curvature
Lesser sac / omentum
What is surface anatomy of the liver
Ribs 7-11
Right side
What is produced in the liver and where does it go
Bile
Secreted into R and L hepatic ducts which go to gall bladder for storage
What happens during a meal to allow bile into duodenum
Gall bladder contracts
Bile travels out of cystic duct and joins with R and L hepatic to form common hepatic duct
Pancreatic duct containing bicarbonate and digestive enzymes joins
What is the artery of the gall bladder
Cystic artery
What is the triangle of clot
Triangle between common hepatic, cystic and visceral surface of liver
How is pancreas peritonised
Retroperitoneal
Where do pancreatic and bile duct open into
2nd part of duodenum at sphincter of oddi
What is behind the neck of the pancreas
Portal vein
Where is spleen found
Ribs 9-11 on L side
Intraperintoneal except hilum
What supplies spleen
Celiac trunk originating at T12 of aorta
What does celiac trunk divide into
Left gastric - lesser curvature of stomach
Hepatic - liver and gall bladder
Splenic - superior margin of pancreas
What makes up the midgut
Duodenum Jejunum Ileum Cecum Appendix Ascending colon Right half of transverse colon
What is the shortest and widest part of small intestine
Duodenum
What is the blood supply of the small intestine
Superior mesenteric - L1
What distinguishes large intestine from small
Mental appendicies
Haustra
Teniae coli - thickened bands of smooth muscle
What makes up the large intestine
Caecum Ascending colon Transverse Descending Sigmoid -> rectum at S3
What is the appendix
Intestinal diverticulum
Lymphatic tissue
What is most common appendix position
Retrocecal
What supplies appendix
Inferior mesenteric - L3
What are the 4 layers of the alimentary canal
Inner mucosa
Submucosa
Smooth muscle (muscular externa)
Serosa - connective tissue covering or adventitia if around organ / blood vessel
What makes up the inner mucosa
Single layer epithelium
Lamina propria
Muscularis mucosae
What type of epithelium
Stratified squamous non keratinised - mouth / oesophagus / anal canal
Simple columnar - stomach and intestines
What is in the sub mucosa
Submucosal plexus - parasympathetic
Submucosal glands in duodenum and oesophagus - secrete mucous and bicarbonate to neutralise acid
What are the two layers of smooth muscle
Inside circular layer - constricts
Outside longitudinal layer - shortens tube
What is also present in smooth muscle layer
Myenteric plexus - motor activity of muscle
Myenteric + submucosal = enteric nervous system
What are the two layers of peritoneum
Parietal
Visceral - covers organs
Peritoneal fluid between
Why can you get infection more easily in female
Communication pathway through uterine tubes and vagina
In males it is closed so infection only from damage
What is the peritoneal cavity divided into
Greater sac Lesser sac (omenta bursa)
What links greater and lesser sac
Epiploic foramen
What increases SA of small intestine
Small intestine has villi which have microvilli
What increases SA of small intestine
Small intestine has villi which have microvilli
What is a mesentery
Double layer of peritoneum
Occurs due to invagination by an organ
Allows neuromuscular communication between organ and posterior body wall
What is the peritoneal ligament
Double layer of peritoneum that connects an organ with another organ or abdominal wall
What is falciform ligament
Connects liver to wall
What is omentum
Double layer of peritoneum passing from stomach and duodenum to other organs or body wall
What is lymphatic drainage of foregut, midgut, hindgut
Celiac
Superior mesenteric
Infection mesenteric
What are the three terminal groups of lumbar nodes
Pre-aortic - celiac, superior and inferior mesenteric
Lateral aortic
Retro-aortic
What nerves supply the GI tract
Para - vagus and pelvic splanchnic
Sympa - abdoinopelvic splanchnic nerves
T5-T9 = greater
T10-T11 = lesser
T12 = least
Somatic
What is the Venus drainage
Hepatic portal vein formed by splenic and superior mesenteric vein at L2
Carries deoxygenated nutrient rich blood to liver
R+L hepatic artery carry oxygenated blood
What is porto-caval anastomoses
Connection between portal venous and systemic
Useful if there is a block in the portal vein so blood can reach IVC without travelling through liver
What happens if shunt
Haemorrhoids
Esophageal varices
Caput medusa
What is the arterial supply of the GI tract
Celiac trunk - stomach, small intestine and pancreas
Superior mesenteric - small intestine, caecum, ascending and transverse colon
Inferior mesenteric - descending colon, sigmoid, rectum and appendix
What is the venous drainage of the GI tract
Stomach - gastric vein
Superior mesenteric vein
Inferior mesenteric vein
All drain into hepatic portal then into IVC
What controls the GI tract
Autonomic
Enteric nervous system
What is primary stimulus for secretion and motility
Parasympathetic via vagus
What stimulates salvation
Facial - sublingual, submandibular, lacrimal
Glossopharyngeal - parotid
Vagus doesn’t innervate head or neck
What does sympathetic do
Splanchnic nerve
Inhibitory
Increases salivation but para is primary stimulus
