Overview of Gastrointestinal Tract Flashcards
When does the primordial gut tube form?
4 week of human development
Where is the primordial gut tube derived from?
From endoderm lining of the yolk sac
What are the foregut structures?
Primordial pharynx and derivatives
Lower resp. system
Oesophagus and stomach
Duodenum
Liver and biliary apparatus
What is the artery of the foregut?
Coeliac trunk
What are the 3 constrictions of the oesophagus?
Cervical
Thoracic
Diaphragmatic
What are the parts of the stomach?
Cardia
Fundus
Body
Pyloric
What is the function of the pyloric sphincter?
Control discharge of stomach contents into the duodenum
What structures lie upon the stomach (stomach bed)?
Diaphragm
Spleen
Left kidney
Adrenal gland
Splenic artery
Pancreas
Transverse mesocolon
Colon
Describe the function of the biliary ducts
Carry bile from liver to gallbladder
Where is bile produced and stored?
Produced in liver and stored in gallbladder
What is the artery which supplies the gallbladder?
Cystic artery which lies in the triangle of calot
Explain the triangle of Calot
Hepatic duct, cystic duct and visceral surface of the liver
What is the pancreas function?
Accessory digestive gland
Exocrine and endocrine functions
Where does pancreas lie?
Retroperitoneal
Lies along the transpyloric plane L1/L2
What are the parts of the pancreas?
Head, Neck, Body and Tail
What is the origin of the celiac trunk?
Abdominal aorta at T12
What are the main branches of the celiac trunk?
Left gastric artery
Hepatic artery
Splenic artery
What are the 3 arteries that the abdominal aorta?
Celiac trunk
Superior mesentery artery
Inferior mesentery artery
What organs are in the midgut structures?
Small intestine including duodenum
Cecum
Ascending colon
Right half to 2/3 of transverse colon
What is the duodenum?
Shortest and widest part of the small intestine
Its second part receives bile and pancreatic duct
Explain a duodenal ulcer
Inflammatory erosions of duodenal wall - mainly 1st part
What are some differences of the jejunum and the ileum?
Jejunum has long vesa recta instead of short
Ileum has more fat in mesentery
Ileum had more lymphoid nodules
What is the artery which supplies midgut?
Superior mesentery artery
What level of abdominal aorta is superior mesenteric artery branch from?
L1
What are the main branches of the superior mesenteric artery?
Jejunal
Ileal arteries
What are the structures of the hindgut?
Left 1/3 of transverse colon
Descending colon
Sigmoid colon
Rectum
Upper part of anal canal
Epithelium of urinary canal and most of uretha
What is the artery suppling the hindgut?
Inferior mesenteric artery
How can the large intestine be distinguished from the small intestine?
Omental appendices - small fatty projections
Haustra or sacculations
Teniae coli - thickened bands of smooth muscle
Describe the appendix
Blind intestinal diverticulum with masses of lymphatic tissue
Variable position - retrocecal most common
What is Macburney’s Point?
Site of max. tenderness in acute appendicitis
What is the level of inferior mesenteric artery branches from abdominal aorta?
L3
What are the branches of the inferior mesenteric artery?
Left colic
Sigmoid arteries
Superior rectal artery
What is the terminal branch of the inferior mesenteric artery?
Superior rectal artery
What is the innervation of the abdominal organs?
Autonomic
Parasympathetic - vagus nerve and pelvic splanchnic nerve (S2-4)
Sympathetic nerve - abdominal splanchnic nerves, prevertebral sympathetic ganglia and abdominal aortic plexus
What is the function of the portal vein?
Transports venous blood from the spleen, pancreas, gallbladder and abdominal part of GIT
What is the formation of the portal vein?
Union of splenic vein with superior mesenteric vein
What is the location of the portal vein?
Behind the neck of the pancreas - L2
What are 3 sites of porto-venal shunts?
Anorectal junction
Gastroesophageal junction
At umbilicus
What are some consequences of venous enlargement during portal obstruction?
Haemorrhoids
Oesophageal varices
Caput medusae
Describe the lymphatic drainage of the GIT
Thoracic duct receives most from wall and organs
Lymph vessels run with corresponding arteries
What are the 3 terminal groups of lumbar nodes?
Pre-aortic - drains organs supplied by anterior branches of aorta
Lateral aortic
Retro-aortic - posterior abdominal wall
