Chapter 93: Colon

Question 1

The cecum is a diverticulum that connects to the proximal colon. Where does cecocolic orifice lie in relation to the ileocolic orifice?

Answer 1

1cm caudal

Question 2

What are the three parts of the colon?

Answer 2

Ascending
Transverse
Descending (longest portion)

Question 3

The cranial mesenteric artery branches to the common colic artery to feed the colon. What feeds each area:
Cecum?
Ascending?
Transverse?
Descending?

Answer 3

Cecum: ileocolic artery
Ascending: ileocolic proximally, right colic distally
Transverse: Right colic and middle colic
Descending:
Proximal - middle colic
Distal -left colic off the caudal mesenteric
**Most distal - cranial rectal artery

Question 4

Arteries connect to the colon via vasa recta - what are these?

Answer 4

Short arterial branches that penetrate the muscular layer on antimesenteric portions.

Question 5

Caudal colon venous drainage is what?
Cranial colon venous drainage?

Answer 5

Caudal: Portal vein via left colic -> caudal mesenteric vein

Cranial: Portal vein via cecal -> ileocolic -> right colic -> middle colic vein

Question 6

What are (3) functions of the colon?

Answer 6

1. Store feces (distal colon)
2. Reservoir for microbiome
3. Maintain fluid and electrolyte balance (proximal)

Question 7

How much fluid does the colon absorb per day?

Answer 7

1.5 liters

Question 8

Colonic healing:
How long does mucosal healing take?

How long to 30% strength of submucosa? 75%?

Answer 8

Mucosa - 3 days

Submucosa is 30% at 48hr and 75% at 4 months (slower than SI)

Question 9

Perfusion of the colon is vital for healing. If PaO2 is less than ____ collagen formation will not occur. and if < 10mmHg what will fail?

Answer 9

<40mmHg = no collagen

<10mmHg = failure of angiogenesis and epithelial hyperplasia