circulation

Question 1

Law of Laplace equation

Answer 1

tension = pressure x radius

Question 2

circumferential wall stress equation

Answer 2

circumferential wall stress = tension/wall thickness

Question 3

effect of increased radius on blood flow and wall stress

Answer 3

increases flow and wall stress

Question 4

pressure gradient calculation for Laplace

Answer 4

pressure gradient = P1 - P2 (as blood flows down vessel)

Question 5

define aneurysm

Answer 5

outward bulging, likened to a bubble or balloon, caused by a localised, abnormal, weak spot on a blood endothelium

Question 6

effect on aneurysm on radius, tension and fate of endothelium

Answer 6

increase radius of vessel so tension of wall must increase as same pressure; however if fibres weakened, force can’t be produced so aneurysm exapands until ruptures

Question 7

type of aneurysm in gut for GIT

Answer 7

diverticuli

Question 8

to produce higher tension what is required as radius increases at given pressure

Answer 8

thicker wall