Lecture 7 Unit 1 Flashcards
what is hemodynamics
the study of fluid flow in the vascular system
in which way does fluid flow?
from regions of high pressure to regions of lower pressure
what is resistance to fluid flow caused by
friction between the molecules in the fluid and the walls of the tube
what always reduces flow?
fictional resistance
what is the flow velocity in the capillaries?
0.1 cm/sec
why aren’t blood pressures equal throughout the cardiovascular system?
if they were equal blood would not flow because flow requires a pressure difference or driving pressure
blood pressure is what?
pulsatile
what does pulsatile mean?
blood pressure peaks during systole and falls during diastole
what is the formula for estimating mean arterial blood pressure?
MAP = DBP + 1/3 (SBP - DBP)
What are the two factors arterial BP reflects of the arteries close to the heart?
- their elasticity
- the amount of blood forced into them at any given time
What is the formula for arterial compliance?
C = dV / dP
what does high compliance and elasticity allow?
the flow to be propelled throughout the cardiac cycle
how is blood propelled throughout the cardiac cycle?
the alternation expansion and recoil of the arteries after each contraction of the left ventricle
what is the pressure wave from expansion and recoiling of the arteries called?
the pulse
What does Pulse Pressure (PP) represent?
the stroke volume
do stiff arteries have a low or high compliance?
low
what kind of arteries is hypertension associated with?
stiff arteries
is the pressure higher in the pulmonary circuit or the systemic circuit?
the systemic circuit
what is the mean pressure in the pulmonary artery at rest?
14 mmHg
what is the mean left atrial pressure?
5 mmHg
what is the pressure gradient for left atrial filling?
9 mmHg
what is blood flow proportional to?
the driving pressure
what is blood flow inversely proportional to?
the resistance to flow
what is the formula for flow?
flow = driving pressure / resistance
how is resistance calculated?
after flow and pressure are measured
what is resistance the sum of?
all the forces that retard flow
what are the two ways to calculate cardiac output?
- CO= SV x HR
- CO = pressure gradient / R
