Pouisuielle's Law

Poiseuille's Law:

This equation describes the flow of fluids through cylindrical tubes:

		V=( P * pi * r^4 ) /  (8 * n *l)
			P = the driving pressure
			r = radius of path
			n= viscosity
			l = length of path

The law is applicable in describing the flow of blood in the veins and arteries, as well as air flow and pressure down the bronchioles This equation is valid only when describing laminar flow: flow that occurs as if moving as a series of individual layers.

Poiseuille's Law gives us insight on such things as the pressures of the blood-gas barrier in the alveoli, how the body can increase blood flow or reduce resistance to flow (e.g. enlarging the veins and arteries near the heart), and the amount of work the heart does to pump blood or the amount of work needed to be done to bring air from our mouth down to the alveoli.

Which are all topics covered in the class, thus far.

--Hoa T. Le

Work Hard. Have Fun. FIGHT ON!!!

A sample problem:

Name the two muscle groups that the body can use to increase air flow down the bronchioles?

Answers:

The intercostal and the diaphragm. The body can make both expand the lung with greater force, thus with greater pressure, which in turns increases air flow.

For more information on this topic, please refer to West , page 103.

Also, check out the following links that may be helpful:

• Viscosity!
• Poisuielle's Law
• And, as always, if you have questions, or if you can suggest a helpful link, please e-mail me.

No!
Please don't make me go to any of those pages!
I want to go somewhere completely different!

This page was written by Hoa Le , a student in this course.

BME 403 Pages maintained by the T.A., Douglas Miles.