Digestive system: foregut and midgut Flashcards
How is blood pumped into the hepatic portal system
Blood is pumped from the heart into arteries which go into arterioles then capillaries that line the lamina propria of the small and large intestine.
In the hepatic portal system after the blood is in the lamina propria what happens
the venules drain the capillaries which give rise to the veins of the hepatic portal system , these become venules again and exchange substances to the second capillaries (hepatic sinusoids) which give rise to the terminal hepatic venules which dump into hepatic veins
Where does the hepatic portal vein dump
into the parenchyma of the liver
What does the portal vein collect
GI visceral blood (blood from gut tube, foregut, midgut, hindgut, accessory digestive glands and the spleen)
What do the left and right gastric veins drain
drain from the lesser curvature of the stomach directly into the portal vein.
What do the gastroepiploic veins drain to
the portal vein and splenic vein
What does the splenic vein drain blood from
the spleen
What veins go from the pancreas into the splenic vein
pancreatic veins
What does the hepatic portal system not have
Valves - so blood flow can be in any direction depending on pressure gradient
What are the porto-caval anastomoses
tissue areas in the GI tract where blood drains into hepatic portal system and caval veins
Name the porto-caval anastomoses
oesophagus, rectum and superficial abdomen
What does the inferior vena cava split into
the common iliac vein and then gives rise to an internal and external iliac vein
How does the left gastric vein drain blood from the distal oesophagus
drains from oesophagus to the hepatic portal vein to the liver through the sinusoids of portal veins in to the vena cava, back to the heart
What is the caval drainage of the distal oesophagus
through esophageal veins that go directly to the azygous veins then to the superior vena cava
What happens if there is a congestion into the portal vein
blood starts flowing backwards into its tributaries (can do this because there are no valves) back into the distal oesophagus. The blood then gets pushed into the oesophageal veins that go into the azygous veins
What is congestion in the portal vein called
portal hypertension
What does the backflow of blood from the portal vein cause
esophageal varices where they swell (due to increased blood flow) and can become varicose veins and burst
What is the portal drainage of the rectum
the superior rectal vein
What does the superior rectal vein drain into
the inferior mesenteric vein which goes into the splenic vein then into the hepatic portal vein into the liver
What is the caval drainage of the rectum
drains into the middle and inferior rectal veins
What do the middle and inferior rectal veins drain into
the internal iliac vein which goes into the common iliac vein into the inferior vena cava back to the heart
What does congestion in the portal vein cause to the rectum
causes blood to be directed into the inferior rectal veins which swell and cause internal haemorrhoids
What is the caval drainage for the abdominal wall - superficial fascia
superfifical epigastric veins
What do the superficial epigastric veins drain into
the femoral vein which becomes the external iliac and then goes into the common iliac then the inferior vena cava back to the heart
What does the portal drainage (Camper’s fascia) of the abdominal wall involve
periumbilical vein
Where do the periumbilical veins run
They follow the round ligament in through the umbilicus and down the falciform ligament to the liver then into the portal vein
What does congestion in the portal vein of the abdominal wall cause
vein causes blood to dilate the periumbilical veins causing caput medusa
Where does the superior mesenteric artery arise
from the abdominal aorta in the upper boarder of L1
What branches does the superior mesenteric artery give off
a series of jejunal and ileal branches which give rise to a series of short arteries - the vasa recta
What do the vasa recta form
arterial arcades
What runs parallel to the small intestine
a channel formed of various jejunal/ileal branches which anastomose to form the arterial arcases
What are the vasa recta
the short, straight channels in the arterial arcades
Name the colic arteries that come off the superior mesenteric artery
middle colic artery, right colic artery and ileocolic artery
Where do the colic arteries run
towards the colon and cecum in arterial arcades
What is the marginal artery
the arteries that come off the arterial arcades to supply the colon
What does the ileocolic artery supply
the proximal portion of the colon, the cecum
What artery does the ileocolic artery give rise to
the appendicular artery
Where does the appendicular artery travel
this goes posterior to the ileum and supplies the appendix
Where does the inferior mesenteric artery come off
from abdominal aorta at L3
What does the inferior mesenteric artery branch off into
the left colic artery
Where does the left colic artery run
heads retroperitoneal towards the descending colon
At the descending colon, what does the left colic artery branch into
the ascending and descending branches of the left colic artery
What do the ascending and descending branches of the left colic artery run into
the marginal artery which continues all the way along the large intestine
What does the marginal artery recieve as it runs parallel to the sigmoid colon
sigmoidal arteries which come off the mesenteric artery
What is the final branch that comes off the inferior mesenteric artery
The superior rectal artery
What does the superior rectal artery supply
the upper portions of the rectum
What supplies the lower portions of the rectum
internal iliac arter
What surround each of the main vessels e.g., coeliac trunk
aortic plexuses (contain sympathetic and parasympathetic fibres)
What plexus surrounds the coealiac trunk
the coeliac plxus
What plexus surrounds the superior mesenteric artery
superior mesenteric plexus
What plexus surrounds the inferior mesenteric plexus
the inferior mesenteric plexus
What does the superior hypogastric plexus surround
the bifurication of the aorta
What surrounds each internal iliac artery
the 2 inferior hypogastric plexus
How are the inferior and superior hypogastric plexuses in connection with each other
through the right and left hypogastric nerve
What runs along the spinal cord
the sympathetic chain
What does the sympathetic chain contain
sympathetic fibres that have left the spinal cord from the thoracic and lumbar regions
Where can a sympathetic fibre associated with the abdomen leave at
the 5th, 6th, 7th, 8th, 9th, 10th, 11th and 13th thoracic spinal cord segment. Will also leave from the 1st, 2nd and 3rd lumbar segments
What are pre-synaptic sympathetic fibres
the sympathetic nerve that passes towards the sympathetic chain from the spinal cord
How does a nerve signal transmit to the heart/lungs
A sympathetic nerve that passes towards the thoracic viscera then you form a synapse at the 1st, 2nd and 3rd lumbar segments with a post-synaptic sympathetic fibre where they will then pass to the heart or the lungs
Name the 3 pre-aortic ganglia
the coeliac ganglia, superior mesenteric ganglia and the inferior mesenteric ganglia.
What does an abdominal sympathetic nerve’s pre-synaptic fibre do
pass straight through the sympathetic chain without synapsing to synapse at pre-aortic ganglion
What do sympathetic fibres from T5-T9 do
pass towards the coeliac ganglia (pass through sympathetic chain without synapsing) - this is a pre-synaptic fibre
What do fibres from T5-T9 run in
the greater splanchnic nerve
What does the pre-synaptic ganglia do when it reached the coeliac ganglia
synapse with a post-synaptic fibre
Once the pre-synaptic fibre has synapsed at the coeliac plexus what does it do
passes within the coeliac plexus towards the branches of the coeliac trunk where it goes to the foregut
What do the nerves from the coeliac plexus run alongside
the arteries that supply the foregut as periarterial branches and the liver sympathetic input to the foregut
What does T10 and T11 give rise to
pre-synaptic fibres that goes towards the superior mesenteric ganglia as the lesser splanchnic nerve
What do the T10-T11 pre-synaptic fibres do
forms a synapse with a post-synaptic fibre that goes towards the superior mesenteric plexus and runs alongside the branches of the superior mesenteric artery to supply sympathetic input to the midgut
What nerve reinforces the input from the lesser splanchnic nerve
the least splanchnic nerve from T12 - follows same route as lesser splanchnic nerve
Where does the inferior mesenteric ganglia receive input from
1st, 2nd and 3rd lumbar segments - lumbar splanchnic nerves
Where do the lumbar splanchnic nerves synpase
through the inferior mesenteric plexus alongside the inferior mesenteric artery through the hind gut
What provides the parasympathetic input
vagus nerve and pelvic splanchnic nerves
Where does the vagus nerve come from and where does it run
the medulla oblongata of the brain stem and this enters the abdomen via the oesophageal hiatus that runs over the vagus trunks and over the surface of the stomach
Where does the posterior trunk of the vagus trunk come from
the coeliac plexus
What fibre is the vagus nerve
pre-synaptic - does not synpase with any ganglia
What plexus does the vagus nerve run with and what does it follow
runs within the coeliac plexus and then follows the arterial supply to the organs of the foregut
Where does the vagus nerve synapse
with a short post-synpatic fibre within the wall of the target organ
What does the posterior trunk of the vagus nerve do
passes down into the superior mesenteric plexus where this pre-synaptic fibre follows the branches of the superior mesenteric artery towards the midgut
What does the posterior trunk of the vagus nerve synapse with
at the wall of the target organ with a post-synaptic fibre.
Where do the pelvic splanchnic nerves come from
S2, S3 and S4 of the sacral spinal cord
What does the pelvic splanchnic nerve run to
the hypogastric plexus
What do the pelvic splanchnic nerves do within the inferior hypogastric plexus
ascend within the hypogastric nerves to the superior hypogastric plexus
Where do the nerves from the superior hypogastric plexus run
towards the inferior mesenteric plexus and then towards the hindgut, alongside branches of the inferior mesenteric artery
Where do the pelvic splanchnic nerves synapse
with a short post-synaptic fibre at the wall of the target organ
What does the coeliac trunk supply
supplies the structures in the foregut: the stomach, proximal duodenum, spleen, liver and most of the pancreas
Where does the coeliac trunk arise
right at the top of the aortic opening, between the crura of the diaphragm
Name the 3 branches of the coeliac trunk
The small left gastric artery (goes straight up), common hepatic artery (goes to the right) and splenic arteries (goes to the left).
How does the splenic artery goes towards the spleen
along the upper border of the pancreas
How does the splenic artery end
by dividing into several large branches as it reaches the hilum of the spleen
What does the common hepatic artery divide into
the hepatic artery and the gastro-duodenal artery
Where does the hepatic artery run
upwards and to the right to supply the liver
What structures are beneath the hepatic artery
common bile duct and portal vein (runs close to them)
When and what does the hepatic artery divide into
right and left branches as it approaches the porta hepatis
Where does the right gastric artery arise from
the hepatic artery
Where does the right gastroepiploic artery arise from
the gastroduodenal artery
After the gastroduodenal artery splits what does it continue as
the pancreaticoduodenal artery
Where does the pancreaticoduodenal artery run
Runs downward behind the duodenum, supplying it and the head of the pancreas
Where does the stomach get most of its blood from
2 arcades - 1 that runs in the greater omentum (by the greater curve) and 1 that runs in the lesser omentum (by the lesser curve)
What supplies the arcade in the lesser omentum
right and left gastric artery
What supplies the arcade in the greater omentum
left gastroepiploic and right gastroepiploic
What do the right and left gastroepiploic arteries do
join together to form a continuous loop
What 2 veins run with the superior mesenteric artery
splenic vein (in front) and left renal vein (behind)
Where does the superior mesenteric artery run - till it gets to the pancreas
. It gives off branches to the pancreas and duodenum then emerges from beneath the pancreas, along with the superior mesenteric vein
Where does the superior mesenteric artery run when it gets to the pancreas
It passes in front of the uncinate process of the pancreas and in front of the third part of the duodenum, as it does it gives off many branches
Where do the branches of superior mesenteric artery enter
some enter the mesentery and 2 run down the retroperitoneum, 1 passes upward to the transverse mesocolon
Where does the ileocolic artery go
towards the cecum
Where does the right colic and the middle colic go
Go to the ascending and transverse colon
What does the left colic artery supply
the ascending and distal part of the transverse colon
Where does most of the stomach lie
above the costal margin
What are the features of the jejunum compared to the ileum
is wider, thicker walled, large, tll and closely packed pliace circulares
How is the jejunoileum attached to the posterior abdominal wall
by a mesentery that carries the blood vessels, nerves and lymphatics.
Where does the mesentery of the jejunileum run
begins in front of the last part of the duodenum, runs downward and to the right, ending close to the cecum
Describe the mucosal lining in the jejunum and the ileum
The mucosal lining is thrown into folds, that project into the ileum and are more pronounced jejunum
What does the mucosal lining contain
lining contains projections (villi) to increase its surface area
Where does the jejunum start
at the duodenojejunal flexure
Where does the ileum join the large intestine
at the ileocecal valve
What consists the portal triad
Anterior right – bile duct. Anterior, left – hepatic artery. Posterior – portal vein
What are haustra in the large intestine
sacculations of the wall between the taeniae coli
What are taeniae coli in the large intestine
3 bonds of the longitudinal layer of the smooth muscles in the wall
What are appendices epiploicae in the large intestine
fatty projections
