GI tract Flashcards
The GI tract is a continuous tube extending from the ____ to the ____
mouth
anus
what are the main organs/parts of the body involved in the GI tract
oral cavity pharynx oesophagus stomach small intestine large intestine rectum and anal canal
what are the accessory organs
teeth tongue salivary glands pancreas liver gallbladder
epithelial lining of the primative gut tube is derived from the ___
embryonic endoderm
the connective tissue , smooth muscle and peritoneal covering of the wall of the tube are derived from the ____
splanchnic mesoderm
where does the foregut extend from and to
from the mouth to the point where the hepatopancreatic ampula enters the duodenum
where does the midgut extend from and to
from the point where the hepatopancreatic ampulla enters the duodenum to the junction between the proximal 2/3 and distal 1/3 of the transverse colon
where does the hindgut extend from and to
junction between the proximal 2/3 and distal 1/3 of the transverse colon to the anus
the gut tube is vascularised by branches from ___
the abdominal aorta
foregut is supplied with blood from ___
coeliac trunk
midgut is supplied with blood from ___
superior mesenteric artery
hindgut is supplied with blood from ___
inferior mesenteric artery
insufficient blood supply in the GI tract may lead to ___
ischemic collitis
which veins drain blood from the major parts of the GIT
hepatic veins
drains through to the inferior vena cava
what is a portal vein
a vein conveying blood to the liver from the spleen, stomach, pancreas and intestines
what is a systemic vein
one capillary bed to the heart
derivatives of the gut tube
pharynx larynx oesophagus stomach duodenum (proximal half) liver gallbladder pancreas
derivatives of the midgut
duodenum (distal half)
jejunum
cecum
ascending and transverse colon
derivatives of the hindgut
transverse colon descending colon sigmoid colon rectum anal canal
the intestinal loops protrude through the ___ region of the developing foetus to form the physiological umbilical hernia
ubilical region
the intestinal loops usually return to the abdominal cavity through several rotations of the ___
gut tube
what is omphalocele
failure of the intestinal loops to return to the abdominal cavity
what is diverticula of the colon
small out pocketing pouches from the wall of the colon
may lead to diverticulitis
the peritoneum lines the walls of which cavity
abdominal
what are the 2 layers of the peritoneum
parietal - lines the inner surface of the walls
visceral - covers most of the abdominal viscera
what is the peritoneal caivty
potential space between the parietal and visceral peritoneal layers
what is intraperitoneal
when organs are completely covered by the visceral peritoneum
what is retroperitoneal
when organs lie behind the peritoneum and are partially covered on their anterior surface only (e.g. kidney or pancreas)
what is a mesentery
- double layer of peritoneum that enclose organs and connect them to either the anterior or posterior walls of the abdomen
what does the mesentery called omentum connect?
stomach to transverse colon
what does the mesentery called the lesser omentum connect?
connects stomach and bit of duodenum to the liver
what does the falciform ligament connect?
liver to anterior abdominal wall
is the stomach higher or lower in slim people than fat people
slim people have lower stomachs
cancer of the head of the pancreas often compresses and obstructs the ____
biile duct and/or the hepatopancreatic ampulla
cancer of the head of the pancreas leads to enlargement of the ____
gallbladder
what surgical procedure is used to treat cancer in the head of the pancreas
pancreatoduodenoctomy (whipple’s procedure)
what does the blockage of hepatopancreatic ampulla by gallstone lead to
pancreatitis due to reflux of the bile into the pancreatic duct
right and left lobes of the liver are separated by the ___
falciform ligament
quadrate and caudate lobes of the liver are separated by the ____
sagittal fissures and the transverse porta hepatitis
true or false each lobe (right and left) receives its own primary branch of hepativ artery and portal vein
true
what lobe is considered to be the third liver lobe
caudate lobe
how many segments is the liver divided into
8
by what 2 blood vessels is the liver divided into
hepatic portal vein
hepatic artery
what % of blood does the hepatic portal vein supply to the liver
75-80%
what % of blood does the hepatic artery supply to the liver
20-25%
what % of the lymph entering the thoracic duct comes from the liver
between 25 and 50%
what makes up the extrahepatic part of the billiary tree
right and left hepatic duct
common hepatic duct
bile ducts
hepatopancreatic ampulla
what fraction does the jejunum make up of the small intestine
2/5
what fraction does the ileum make up of the small intestine
3/5
is this true for the jejunum or the ileum?
fewer loops of arterial cascades
jejunum
is this true for the jejunum or the ileum?
longer vasa recta within its mesentery
jejunum
what is a mesenteric border
concave margin of a small bowel loop
faces towards the root of the mesentery
what is an anti-mesenteric border
convex margin of a small bowel loop
faces away from the root of the mesentery
example of intra-abdominal disease of the mesenteric border
diverticulosis
example of intra-abdominal disease of the anti-mesenteric border
meckel’s diverticulum
3 distinguishing features of the colon
omental appendices - small fatty projections
teniae coli - 3 longitudinal smooth muscle bands
haustra
where is the appendix usually located
mcburneys point
retro-colic or retro-caecal (60-75%)
anal canal is developed from 2 sources:
endodermal cloaca of the hindgut upper (2/3)
extodermal cloaca lower (1/3)
what is the pectinate
the line that divides the upper two thirds and lower third of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction.
which nerves carry sympathetic ad visceral afferent fibres to and from the GIT
splanchnic
which nerve carries parasympathetic and visceral afferent fibres to and from the GIT
vagus nerve
