Class Notes (837,539)
Canada (510,303)
Physiology (1,062)
Tom Stavraky (262)

Vascular function

2 Pages
Unlock Document

Physiology 3120
Tom Stavraky

Human Physiology Wednesday, January 20, 2010 CV VIII” Vascular Function • Relationship between pressure, flow, and resistance  Pressure gradient makes the blood flow; gradient is the difference between the beginning and end of the blood vessel/systemic circulation  In systemic circulation, the pressure gradient is equal t1 P (pressure at end of vessel is 0mmHg)  Flow = pressure gradient/resistance; flow is proportional to pressure gradient & inversely proportional to resistance  Resistance depends on viscosity (directly), length of vessel (directly) and vessel radius (inversely to the exponent 4)  The relationship between these 4 variables is summarized in the Poiseuille-Hagen equation • Laminar & turbulent flow of blood  Laminar  Streamline flow  Parallel to walls of vessel  Small portion of the blood (closest to the wall) moves very slowly; as you move inward toward the centre, the velocity increases so that the blood in the middle layer will flow with the greatest speed  Silent flow  Turbulent  When flow velocity increases to a certain point, the flow will become turbulent  Irregular motion  Parallel as well as perpendicular flow  Creates sound  Probability of turbulent flow (Reynold’s number) • Ratio of inertial to viscous forces • When it exceeds a critical value, turbulence occurs • Turbulence occurs sometimes in the ascending aorta at the peak of systole; also occurs more commonly in anemia due to decreased blood viscosity • Capillary circulation  Point where arterioles connect to capillaries  precapillary sphincters (made up of smooth muscle cells); therefore, blood flow into capillaries is intermittent (i.e. only flows in when sphincter is open)  known as vasomotion in capillaries  Diffusion  Endothelial cells lini
More Less

Related notes for Physiology 3120

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.