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GI > Anatomy of bleeding in the GI tract > Flashcards

Anatomy of bleeding in the GI tract Flashcards

1
Q

describe the components of the large intestine, from proximal to distal.

A 
- Colon 
= caecum
= appendix
= ascending colon
= transverse colon
= descending colon
= sigmoidal colon
  • rectum
  • anal canal
  • anus
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2
Q

what are 3 functions of the large intestine?

A

1) defence
= commensal bacteria

2) absorption
= H20 and electrolytes

3) excretion
= of formed stool

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3
Q

describe the colons anatomical position.

A

= intra-peritoneal (quite mobile)
= secondarily retro-peritoneal
= intra-peritoneal (highly mobile as it has its own mesentery)
= secondarily retro-peritoneal
= intra-peritoneal (quite mobile as it has its own mesentery)

  • inferior to liver
  • inferior to spleen
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4
Q

what are paracolic gutters?

A

= spaces between the colon and the abdominal wall

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5
Q

how many paracolic gutters are there?

A

= 2; right and left

- located between lateral edges of ascending and descending colon and abdominal wall

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6
Q

what are the paracolic gutters part of?

A

= greater sac of peritoneal cavity

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7
Q

what re paracolic gutters potential sites for?

A

= pus collection

  • similar to sub-phrenic or hepatorenal recesses
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8
Q

what are 3 distinguishing features of the colon?

A

1) omental appendices
2) teniae coli
3) haustra

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9
Q

describe the teniae coli.

A

= 3 distinct longitudinal bands of thickened smooth muscle, from caecum to distal end of sigmoid colon
= coming together at the appendix

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10
Q

True or False.

Splenic flexure, usually, lies more superior that hepatic flexure.

A

True

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11
Q

what are omental appendices?

A

= small, fatty, projections

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12
Q

how are haustra formed?

A

= by tonic contractions of tenaie coli

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13
Q

what is used as a contrast in radiology and how is it administered?

A

= barium
- administered via an enema
(enema = procedure in which liquid is injected via the rectum)

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14
Q

where do the caecum and appendix lie?

A

= in the right iliac fossa

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15
Q

describe the position of the appendix?

A

= variable (accounts for why patients have differences when presenting with appendicitis)
= often retro-caecal

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16
Q

where is the appendiceal orrifice?

A

= on postero-medial wall of caecum

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17
Q

where does the appendiceal orrifce correspond with?

A
  • corresponds to McBurney’s point on the anterior abdominal wall
  • 1/3 of the way between right ASIS to umbilicus
  • maximum tenderness in case of appendicitis
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18
Q

where does the sigmoidal colon lie?

A

= in left iliac fossa

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19
Q

describe the mesentery fo the sigmoidal colon?

A

= long mesentery (sigmoid mesocolon)

- giving it a considerable degree of movement

20
Q

what is a negative side to the long mesentery possessed by sigmoidal colon?

A

= the sigmoidal colon is at risk of twisting around itself

sigmoidal volvulus

21
Q

what is sigmoid volvulus and what does it result in?

A

= when the sigmoidal colon twists round itself
= resulting in bowel obstruction
- bowel at risk of infarction if left untreated

22
Q

describe where the abdominal aorta lies?

A

= midline, retroperitoneal structure

- lying anterior to vertebral bodies and to left of IVC

23
Q

how many midline branches does the abdominal aorta have?

A

= 3 midline branches

  • ceoliac trunk (foregut organs)
  • superior mesenteric artery (midgut organs)
  • inferior mesentery artery (hindgut organs)
24
Q

what do the lateral branches of the abdominal aorta supply?

A

= kidneys/adrenal glands
= gonads (testes/ovaries)
= body wall (posterolateral)

25
Q

what does the abdominal aorta bifurcate into?

A

= common iliac (L4)

- further bifurcates to internal and external iliac

26
Q

Name 6 branches of the superior mesenteric artery.

A
  • jejunal and ileal arterries
  • appendicular
  • ileocolic branches
  • right colic artery
  • middle colic artery
  • inferior pancreaticoduodenal

look at the image of the superior mesenteric artery, slide 10.

27
Q

describe the difference between the jejunal and ileal arteries?

A

Jejunum
= longer vasa rectae
= larger and fewer arcades

Ileum
= shorter vasa rectae
= smaller and many arcades

28
Q

Name 3 branches of inferior mesenteric artery.

A
  • left colic artery
  • sigmoidal artery
  • superior rectal artery

look at the image of the superior mesenteric artery, slide 12.

29
Q

what is the marginal artery of drummond?

A

= arterial anastomoses between the branches of the superior mesenteric artery and inferior mesenteric artery

30
Q

what could these anastomoses help prevent?

A

= they could help prevent intestinal ischaemia by providing an alternative (collateral) route by which blood can travel

31
Q

what does the superior rectal artery, a bunch of inferior mesenteric artery, supply?

A

= hindugtt extends too proximal half of the anal canal (the pectinate linen)

32
Q

what is the remainder of the GI tract supplied by?

A

= the internal iliac artery

- there is an anastomoses between these vessels

33
Q

what are the bodies 2 main venous systems and what do they drain?

A

1) hepatic portal system
= drains venous blood from absorptive part of GI tract & associated organs to liver for ‘cleaning’

2) systemic venous system
= drains venous blood from all other organs and tissues into the superior or inferior vena cava

34
Q

what does the inferior vena cava (retro-peritoneal) drain?

A

drains cleaned blood from the hepatic vein into the right atrium

35
Q

what does the hepatic portal vein and splenic vein drain?

A

Hepatic portal vein
= drains blood from foregut, midgut and hindgut structures to the liver for first pass metabolism.

Splenic vein
= drains blood from foregut structures to hepatic portal vein

36
Q

what does the superior mesenteric and inferior mesenteric vein drain?

A

Superoir mesenteric vein
= drains blood from midgut structures to hepatic portal vein

Inferior mesenteric vein
= drains blood from hindgut structures to splenic vein

37
Q

describe the 3 clinically important sites of venous anastomosis between the systemic and portal venous system?

A

= at these sites, the presence of small collateral veins means blood can flow both ways;

  • either into systemic or portal venous system
  • there are no valves in these veins
  • normally there is very little blood flow within these collateral veins
38
Q

what are the 3 parts to the portal-system anastomoses?

A

1) distal end of oesophagus
2) skin around umbilicus
3) rectum/anal canal

39
Q

describe what the inferior and superior part of the distal end of the oesophagus drains?

A

inferior part
= drains into hepatic portal vein

Superior part
= drains into azygous vein

40
Q

describe the skin around umbilicus.

A

= connection between para-umbilical veins and small epigastric veins

  • para-umbilical veins to hepatic portal vein along the round ligament of liver
  • epigastric vein drains to caval system
41
Q

describe the rectum/anal canal?

A

= rectum and superior anal canal drains to inferior mesenteric vein
- inferior parts of GI tract drains to the internal iliac veins

42
Q

what is portal hypertension and what can cause it?

A

= elevation of blood pressure in the portal system

Can be caused by;

  • liver pathology (cirrhosis)
  • tumour compressing HPV
43
Q

what does portal hypertension lead to?

A

= reversal of blood flow

44
Q

what does a larger volume of blood flow to these anastomotic (collateral) areas cause?

A

= them to become varicosed

45
Q

what are 2 clinical features of portal hypertension?

A

1) oesophageal varices
- dilated sub-mucosal collateral veins

2) caput medusae
- dilated para-umbilical and dilated epigastric veins

46
Q

what is haematemesis?

A

= vomiting up blood

47
Q

what are the options for the causes of haematemesis?

A

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

2) bleeding from oesophageal varives
- abnormal dilated veins
- thin walls, therefore the potential to rupture
= filling oeosphagus with blood
- formation often due to pathology affecting portal venous system

GI (43 decks)

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