bleeding in the GI tract

Question 1

large intestine from proximal to distal is made up of…

Answer 1

colon: caesum, appendix, ascending colon, transverse colon, desending colon, sigmoid colon

rectum
anal canal
anus

Question 2

functions of the small intestine

Answer 2

defence - commensal bacteria
absorption - H2O & electrolytes
excretion - of formed stool

Question 3

where are the paracolic gutters found

Answer 3

between lateral edge of ascending colon and descending colon and abdominal wall

Question 4

what can happen in the paracolic gutters and what is it part of

Answer 4

part of peritoneal cavity

potential site for pus collection

Question 5

where do the caecum and appendix lie

Answer 5

both lie in the right illiac fossa

Question 6

where does the appendiceal orifice lie

Answer 6

posteromedical wall of caecum

corresponds to McBurney’s point on the abdominal wall

1/3 of the way between right ASIS to umbilicus

maximum tenderness in case of appendicitis

Question 7

where does the sigmoid colon lie

Answer 7

lies in the left illiac fossa

Question 8

advantages and disadvantages of sigmoid mesocolon

Answer 8

gives considerable degree of movement

neg: sigmoid colon at risk of twisting around itself (sigmoid volvulus)

clinical results in bowel obstruction

bowel at risk of infarction if left untreated

Question 9

where does the abdominal aorta lie

Answer 9

midline retroperitoneal structure

Question 10

3 midline peritoneal branches of abdominal aorta

Answer 10

celiac trunk (foregut organs)

superior mesenteric artery - midgut organs

inferior mesenteric artery - hindgut organs

Question 11

3 lateral branches of abdominal aorta supply what

Answer 11

kidneys/adrenal glands

gonads (testes/ovaries)

body wall (posterolateral)

Question 12

what does the abdominal aorta bifurcate into and at what level

Answer 12

common iliacs

L4

further bifurcates into internal and external iliacs

Question 13

branches of the superior mesenteric artery

Answer 13

inferior pancreaticoduodenal

middle colic artery

right colic artery

ileocolic branches

appendicular

jejunal and ileal arteries

Question 14

jejunal vs ileal arteries

Answer 14

Jejunum
Longer vasa rectae
Larger and fewer arcades

Ileum
Shorter vasa rectae
Smaller and many arcades

Question 15

branches of the inferior mesenteric artery

Answer 15

left colic artery

sigmoid arteries (multiple)

superior rectal artery

Question 16

marginal artery of drummond

Answer 16

There exists arterial anastomoses between the branches of the SMA and the IMA

Depending on the health of these anastomotic vessels, and the speed at which obstruction of a vessel occurs, these anastomoses could help prevent intestinal ischaemia

• by providing an alternative (collateral) route by which blood can travel

Question 17

blood supply to rectum and anal canal

Answer 17

superior rectal artery - a branch of IMA

• hindgut extends to proximal half of the anal canal

remainder of GI tract is supplied by the internal iliac artery

• there is an anastomoes between these vessels

Question 18

main venous systems of the GI tract

Answer 18

hepatic portal venous system
- Drains venous blood from absorptive parts of the GI tract & associated organs to the liver for ‘cleaning’

systemic venous system
- Drains venous blood from all other organs and tissues into the superior or inferior vena cava

Question 19

main the main veins of the GI tract

Answer 19

inferior vena cava
hepatic portal vein
splenic vein
superior mesenteric vein
inferior mesenteric vein

Question 20

3 clinically important sites of venous anastomosis - what is the suggnificance of these veins

Answer 20

the presence of small collateral veins means blood can flow both ways:

Either into the systemic or portal venous system

There are no valves in these veins

Normally there is very little blood flow within these collateral veins

Question 21

3 clinically important sites for portal- systemic anastomoses

Answer 21

skin around ambilicus

distal end of oesophagus

rectum/anal canal

Question 22

venous drainage of the rectum and anal canal

Answer 22

superoir rectal veil –> inferior mesenteric vein

middle rectal vein –> internal iliac vein

inferior rectal vein –> internal iliac vein

Question 23

what is portal hypertension and what is it caused by + leads to

Answer 23

Elevation of blood pressure in the portal system

Can be caused by;
Liver pathology (cirrhosis)
Tumour compressing HPV

Leads to reversal of blood flow

Larger volume of blood flow to these anastomotic (collateral) areas causes them to become varicosed

Question 24

clinical presentation of portal hypertension

Answer 24

Oesophageal varices
Caput medusae
Rectal varices

Question 25

causes of haematemesis

Answer 25

peptic ulcer in wall of stomach or duodenum
erodes through the mucosa
stomach or duodenum fills with blood

Bleeding from oesophageal varices
Abnormal dilated veins
Thin walled, therefore have potential to rupture
Filling oesophagus with blood
Formation often due to pathology affecting the portal venous system