Unit 1 Lecture 7 Flashcards
Define hemodynamics
The study of fluid flow in the circulatory system
What way do fluids ALWAYS flow in the circulatory system?
High pressure -> low pressure
What causes resistance to fluid flow?
Friction between molecules in fluid and the walls of the tube
What is the relationship between flow and resistance?
frictional resistance REDUCES flow
List the increasing order of system’s total cross sectional area
Aorta - 3 cm^2
Vena Cavae - 14 cm^2
Capillaries - 5000 cm^2
What does cross sectional area mean?
Probably the area that the system covers in the body????
What system has the strongest flow velocity?
aorta @ 40 cm/sec
What system has the weakest flow velocity?
capillaries
What is the capillary flow velocity?
0.1 cm/sec
What is unique about capillaries cross sectional area and flow velocity?
They have a very high cross sectional area and very low flow velocity
True or false:
Blood pressure is not equal throughout the cardiovascular system
True, blood requires a pressure difference in order to flow
Define driving pressure
blood’s pressure difference that allows it to flow
What does blood pressure due in relation to the heart beat?
It flows with the heatbeat
What word describes how blood pressure is in phase with the heartbeat
pulsatile
When is blood pressure the highest?
during systole
define systole
heart contraction
When is blood pressure the lowest?
during diastole
define diastole
heart relaxation
Where is there the highest pressure in the body?
Aorta -> arteriest -> arterioles -> capillaries -> venules -> veins -> vena cava
What is the mean arterial blood pressure?
Blood pressure in between systolic and diastolic blood pressure
What is the formula for mean arterial blood pressure?
MAP = DAP + 1/3 (SBP-DBP)
2 factors of arterial blood pressure
- elasticity (distensibility)
2. amount of blood forced into them
Characteristic of arterial blood pressure
BP is pulsatile
Define distensibilty
the capacity to swell as a result from the pressure inside
What is atrial compliance?
the ability of arterial walls to expand and contract passively w/ changes in pressure
Why is high atrial compliance good?
allows the flow to go throughout the body -> expansion and recoil of arteries after contraction
What does the expansion and recoil of arteries generate?
a pulse
What is the formula for pulse pressure?
PP = SBP - DBP
What does the pulse pressure reflect?
stroke volume
What is the formula for articular compliance?
C = dV / dP
Does the pulmonary or systemic circuit have higher blood pressure?
systemic
What is true about pulmonary circulation?
is it very compliant
*it is easier for things to travel through pulmonary arteries vs. systemic arteries bc pul. has bigger arteries, less pressure and less resistance to slow them down
What is the formula for vascular resistance?
R= (viscosity)(vessel length) / radius^4
What are the 2 ways to calculate cardiac output?
CO = SV x HR
CO = pressure gradient / R
What is systemic vascular resistance (SVR)?
Sum of all resistance offered by the vessels of systemic circulation
What is the formula for SVR?
SVR = (mean arterial pressure - mean right arterial pressure (4) ) / CO
What does mean right arterial pressure =?
4 mmHg
What is pulmonary vascular resistance (PVR)?
Sum of all resistance offered by the vessels of pulmonary circulation
What is the formula for PVR?
PVR = (MAP - LMAP(5)) / CO
What does mean left arterial pressure =?
5 mmHg
What is the formula for mean arterial pressure?
MAP = DBP + 1/3 (SBP - DBP)
