During exercise

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

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

Problem

During exercise, heart rate rises to 150150 beats per minute, giving a pulse frequency f=2.5 Hzf = 2.5\,\mathrm{Hz}. The aorta has radius 12.5 mm12.5\,\mathrm{mm}; take blood density ρ=1060 kg m−3\rho = 1060\,\mathrm{kg\,m^{-3}} and viscosity η=3.5 mPa s\eta = 3.5\,\mathrm{mPa\,s}. ((a)) Calculate the viscous penetration depth at this frequency. ((b)) Calculate the Womersley number for the aorta during exercise. ((c)) State how the velocity profile compares with the resting case (α≈19\alpha \approx 19 at 1.2 Hz1.2\,\mathrm{Hz}), and whether Poiseuille's law becomes more or less appropriate.

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