Lab 11 Flashcards
Blood flow is
Proportional to difference in pressure, inverse to resistance
Resistance is
Proportional to length of vessel and viscosity of blood, inversely proportional to fourth power of radius
Vessel length and blood viscosity
Do not change quickly
Pressure
Changes with every cardiac cycle
Greatest resistance to blood flow
Created by vasconstriction of arterioles (changing radius), can redirect flow to/from particular organs
Poiseuille’s law
Change in pressure • radius^4 • pi
Over
Viscosity (n) • vessel length (L) • 8
Increase pressure/flow by
Increasing heart rate or stroke volume
Most important factor for blood flow resistance
Diameter of the tube
Vessel with half the radius of another
Has 16 times the resistance, larger vessel has 16 times the blood flow
Length of tube
Affects resistance to flow, shortening tube increases flow
Viscosity
Decreasing viscosity increases flow
Arterial blood pressure
Equal to cardiac output times total peripheral resistance
Cardiac output affected by
Cardiac rate and stroke volume
Asculatory method
Indirect measure of blood pressure using arterial sounds
Sphygmomanometer
Used to measure blood pressure
First korotkoff sound
Cuff pressure equals systolic pressure
Last Korotkoff sound
Cuff pressure equals diastolic pressure
Average blood pressure
120/80
Pulse pressure
Difference between pressure at systole and diastole in mmHg
Pulse pressure is a reflection of
Stroke volume
Mean arterial pressure
Diastolic pressure + 1/3 pulse pressure
Pre hypertension
120-139/ 80- 89
Stage 1 hypertension
140-159/ 90-99
Stage 2 hypertension
160+/100+
