The GI Tract Flashcards
what makes up the GI tract
oral cavity pharynx oesophagus stomach SI LI rectum and anus
what are the accessory oragsn to the GI travt
teeth tongue salivary glands pancreas liver biliary tree and gall bladder
what is the embryology of the GI tract?
derived from the primative gut - (contributed to by endoermal and mesodermal primary germ layers)
where is the epithelial lining derived from?
the embryonic endoderm (gives rise to specific secretory cells)
what does the splanchnic mesoderm give rise to?
connective tissue
smooth muscle
peritoneal covering
what are the 3 divisions/segments of the GI tract
Foregut - mouth to duodenum entrance
Midgut - duodenum entrance to over halfway down transverse colon
Hindgut - past halfway down transverse colon to anus
what is the vasculature of the 3 sections of the gut
Foregut - coeliac trunk
Midgut - Superior mesenteric artery
Hindgut - Inferior mesenteric artery
how does venous drainage in the GI tract happen
hepatic veins drain all major parts of abdominal GIT
superior and inferior mesenteric veins drain the rest
all to inferior vena cava
What makes up the foregut
pharynx larynx oesophagus stomach duodenum (proximal half) liver biliary tree & gallbladder pnacreas
What makes up the midgut
duodenum (distal half) jejunium (middle part of SI) ileum cecum ascending & transverse colon
What makes up the hindgut
transverse & descending colon
sigmoid colon
rectum
anal canal
what is the normal physiological umbilical hernia?
intestinal loops protruding through the umbilical region of the developing foetus
intestinal loops will return to the abdomen following a number of rotations & fixations of the gut tube
what is aomphalocele
the failure of intestinal loops to return back into the abdominal cavity after the physiological herniation
what is diverticular disease
the condition of having diverticula of the colon (small pocketing pouches from the wall of the colon)
what is Meckel’s ileal diverticulum
embryological remnant of the vitelline duct of the yolk sac attached to the ileocecal
what is the peritoneum?
a smooth thin serous membrane lining the abdominal cavity & some of the viscera
what are the two layers of the peritoneum
parietal and visceral
what are the 4 parts of the stomach
fundus, body, pyloric antrum, pyloric canal
where does the stomach receive its blood supply from
common hepatic artery (gastroduodenal artery, splenic branches)
drained by portal vein
what separates the left and right lobes of the liver
the falciform ligament
what separates the quadrate and caudate lobes of the liver
sagittal fissures and the transverse porta hepatis
how is the liver divided and into how many parts
8 parts by the distributions of portal triad and hepatic vein
what is the livers dual oxygenated blood supply
hepatic portal vein supply 75-80% (40% more oxygen than other systemic veins)
hepatic artery supply other 20-25%
what does the liver have to do with lymph
major producing organ
25-50% of lymph in thoracic duct comes from liver
what are the 4 parts of the pancreas
head, neck, body, tail
what are the 2 ducts within the pancreas and what do they do
main pancreatic duct (unites with bile duct forming hepatopancreatic ampulla of vater (opens to duodenum))
accessory pancreatic duct
where do the duodenum and pancreas get their blood
from branches of splenic, gastroduodenal, superior mesenteric arteries
drainage to hepatic portal vein
where does the pancreas get its nerve supply
from vagus and abdominopelvic splanchnic nerves
what do pancreatic centroacinar cells do
perform exocrine functions, synthesize and secrete the digestive enzymes
what do pancreatic stellate cells do
perform functions relating to tissue repair and destruction of tumour cells
what are the 4 types of pancreatic islet of Langerhans cells
alpha, beta, delta, F-cells
how is the pancreas formed
two buds the endodermal lining of duodenum (dorsal & ventral pancreatic bud)
the fuse
when does insulin secretion begin
around the 5 month of foetal life
what is annular pancreas
improper rotation and migration of the tissue buds - may constrict/obstruct duodenum
what would blockage of the hepatopancreatic ampulla cause (gallstones)
pancreatitis to bile reflux
what is an endoscopic retrograde cholangiopancreatography
fibre optic endoscope passed through mouth to duodenum injecting radiographic contract to produce an image to diagnosis disease
what are the 2 types of pancreatic cancer
exocrine (95%) in head of pancreas
endocrine
what does cancer in the pancreatic head do?
compresses and obstructs the bile duct, enlarges gallbladder leads to obstructive jaundice
what is an pancreatectomy
removal of most or all of the pancreatic cancer
what is Whipples procedure
cancer removal from pancreatic head
what makes the biliary tree
right and left hepatic ducts (forms hepatic duct) + cystic duct = bile duct + main pancreatic duct = hepatopancreatic ampulla
what makes up the small intestine
duodenum (first part, 25cm long takes C shape around pancreas)
Jejunum (proximal 2/5)
Ileum (distal 3/5)
what is the difference between mesenteric and -anti-mesenteric borders
both concave margin of small bowel loop, mesenteric facing towards axis of root of mesentery, other facing away
what is the most common position of the appendix
retro-colic or retro caecal (60-75%)
what is the rectal canal developed from?
endodermal cloaca of hindgut (upper 2/3s)
ectodermal cloaca (lower 1/3)
the sections different in blood, nerve and lymphatic supply
