Dynamics

Homework #4

Name _______________ Lab Day/Time____________
Cardiovascular Dynamics

This experiment examines the factors that effect blood flow through a blood vessel. The rate of blood flow is influenced by the pressure gradient in the vessel, the radius of the vessel, the viscosity of the blood and the length of the vessel. You will be asked to systematically examine each of these factors to determine their effect on blood flow.
Getting Started:
 Login to a CAL lab computer using ZULU
 Open the PhysioEx program
 From the main menu, choose Cardiovascular Dynamics
 The program should open in the “Vessel Resistance” window, but if it doesn’t then you should click Experiment and choose Vessel Resistance.
The experimental apparatus is a set of 2 fluid reservoirs connected by a “blood vessel”. It is possible to vary the values of blood pressure, blood viscosity, vessel length and vessel radius by clicking on the + and – buttons next to those parameters. Once your values have been chosen, you can initiate blood flow between the reservoirs by clicking on the start button below the left reservoir. The program will measure blood flow as a function of time and calculate a flow rate.
We will begin the experiment by varying vessel radius and observing its effects on the rate of blood flow.

Flow as a function of Vessel Radius
Highlight the radius button in the data sets column (far left, bottom)
Set the following values:
 Pressure
100
 Viscosity
3.0
 Length
50
 Radius
3.0
Click the Start button (below the left reservoir) and wait until blood flow is completed.
Click the Record Data button (far right)
Refill the left reservoir by clicking on the Refill button (below the left reservoir)
Repeat the experiment with vessel radii of first 4.0 then 6.0.
Be sure to click the Record Data button after each experiment.
Question
A. Briefly describe the relationship between vessel radius and blood flow. B. What branch of the
ANS primarily