A carotid artery has wall thickness

PHYSICS · Multi-part · Fermi University Physics · Fluids & Continuum Physics · Biophysics & Medical Physics · Bioelectricity, the senses and the physics of the body

Forces, Machines and Signals, Ch Bones, blood and body size

Problem

h_{\rm w} = 1.0\,\mathrm{mm}

, radius

r = 3.0\,\mathrm{mm}

and blood density

\rho = 1060\,\mathrm{kg\,m^{-3}}

. Treat the wall as a thin elastic tube, so the Moens-Korteweg speed applies:

c_{\rm pw} = \sqrt{Eh_{\rm w}/2\rho r}

. The wall is not really thin (

h_{\rm w}/r = 0.33

), so take the result as an estimate. ((a)) At a young effective wall modulus

E = 0.50\,\mathrm{MPa}

, find

c_{\rm pw}

. ((b)) With age the wall stiffens so that

E

triples to

1.5\,\mathrm{MPa}

, with

h_{\rm w}

and

r

unchanged. Find the new

c_{\rm pw}

and state the general relation between the speed ratio and the modulus ratio.

Browse the problem library