Clinical Anatomy of Bleeding in the GI tract Flashcards
What is large intestine made up of?
Colon
Rectum
Anal canal
Anus
Functions of large intestine?
- Defence against commensal bacteria
- Absorption of H2O and electrolytes
- Excretion of formed stool
How many paracolic gutters?
2 (left and right)
Where are paracolic gutters?
-Between the lateral edge of ascending and descending colon and abdominal wall
-They are parts of the greater sac of peritoneal cavity
(similiar to sub-phrenic recesses)
What are paracolic gutters a potential site for?
Collection of pus
What are teniae colo?
3 distinct longitudinal bands of thickened smooth muscle running from caecum to distal end of sigmoid colon
Where do the caecum and appendix lie?
Left iliac fossa
Where is McBurney’s point?
On anterior abdominal wall
1/3 of the way between right ASIS to umbilicus
Where does sigmoid colon lie?
Left iliac fossa
Where does abdominal aorta lie?
It is a midline retroperitoneal structure
Lies anterior to vertebral bodies and to the left of IVC
3 midline branches of the abdominal aorta?
Celiac trunk (foregut)
Superior mesenteric artery (midgut)
Inferior mesenteric Artery (hindgut)
The lateral branches of the abdominal aorta supply?
Kidneys/adrenal glands
Gonads (ovaries/testes)
Body wall
What does abdominal aorta bifurcate into?
Common iliacs which further bifurcate into internal and external iliacs
What exists between the branches of the SMA and the IMA?
Arterial anastamoses
What can arterial anastamoses help prevent and how?
Intestinal ischaemia
Providing an alternative route by which blood can travel
What supplies organs of hindgut?
IMA
What is haematemesis?
Vomiting up blood
Fancy term for vomiting up blood?
Haematemesis
Where could haematemesis be coming from?
Peptic ulcer version
Peptic ulcer in wall of stomach or duodenum>
Erodes through mucosa
Stomach or duodenum fills with blood
Why would my patient be vomiting blood?
- Peptic ulcer eroding through mucosa
- Bleeding from oesphageal varices
Process of bleeding from oesphageal varices?
Bleeding from oesphageal varices >Abnormal dilated veins> thin walled therefore potential ruptures> fill oesphagus with blood
2 main venous systems?
Hepatic portal venous system
Systemic venous system
Where does Hepatic portal venous system drain blood from?
Venous blood from absorptive parts of GI tract and associated organs to liver for cleaning
Where does Systemic venous system drain from?
Drains venous blood from all other organs and tissues into superior/inferior vena cavae
What does IVC do?
Drains cleaned blood from hepatic veins into RA
What does HPV do?
Drains blood from foregut, midgut and hindgut to liver for first pass metabolism
What do splenic veins drain?
Blood from foregut organs to the HPV
What does SMV drain?
Blood from midgut structures to HPV
What does IMV drain?
Blood from hindgut structures to splenic vein
How many sites of venous anastamoses between sympathetic and portal venous systems?
3
called the Portal systemic anastamoses
What happens at portal systemic anastamoses?
Presence of small collateral veins mean blood can flow both ways into systemic or portal venous system
Features of portal systemic anastamoses?
No valves in these veins
V little blood between these collateral veins
What is portal hypertension?
What happens to collateral veins if BP in portal venous system is raised
What is the clinical term given to increased BP?
Portal hypertension
result of liver pathology
What happens in portal hypertension?
Blood is diverted through collateral veins back to systemic venous system.
These veins consequently have a much larger volume of blood than usual- therefore dilate= varicose veins
