Hemodynamics Flashcards
Hemodynamics
Description of the Physical behavior of blood
Examines the interrelationships between flow, pressure gradients, resistance, vessels cross-sectional area and velocity
What type of blood vessel has the highest resistance to blood flow, and therefore affects blood pressure the highest?
Arterioles
Stressed volume
Blood volume that is under high pressure.
Blood found in ARTERIES
Unstressed volume
Blood volume under low pressure
Blood found in VEINS
Macro blood vessel type order pertaining to thickest walls?
Aorta -> vena cava -> arteries -> veins
Macro blood vessel order with respect to diameter size
Vena cava -> aorta -> vein -> arteries
What types of macro blood vessels contain the most elastic tissue
Arteries and the aorta
Micro blood vessel order with respect to diameter
Arterioles -> venules -> terminal arterioles -> capillaries
Micro blood vessel order with respect to wall thickness
Arterioles -> terminal arterioles -> venule -> capillaries
What micro blood vessel contains only a single sheet of endothelium?
Capillaries
What micro vessel contains only endothelium and fibrous tissue?
Venules
A1 vs B2 adrenergic receptors on arterioles
Types of adrenergic receptors that increase or decrease resistance/ diameter
A1 = arterioles contract, causes decreased diameter and increased resistance
B2 = arterioles dialate, causes increased diameter and decreased resistance
Ficks law (V = D(P1-P2)A)
Determines the velocity of blood flow through a vessel/ group of vessels
D= diffusion coefficient
(P1-P2) =. Difference between the pressure gradient
A =. Surface area of the vessel
Velocity of blood flow V= Q/A
Linear velocity that determines the rate of displacement of blood per unit of time.
Q = Flow of the blood per unit of time (usually seconds)
A =. Surface area of the blood vessel/ groups of blood vessels
What blood vessel group has the highest surface area, but lowest blood velocity?
Capillaries
Diameter’s effect on the velocity through a blood vessel
Increase in diameter causes a decrease in velocity
Inversely proportional
Dicrotic notch (incisura)
Secondary “miniature” upstroke corresponding to the increase in aortic pressure upon closure of the aortic valve.
Mean arterial pressure
Diastolic + (Systolic- Diastolic)/3
Average arterial pressure over the course of an entire cardiac cycle.
Takes into account of pulse pressures in the heart.
Total Peripheral resistance (SVR)
SVR = MAP-CVP/CO
Total peripheral resistance throughout the body at any given time.
MAP = mean arterial pressure
CVP = Central venous pressure
atherosclosis with respect to arterial pressure
Causes an increase in both diastolic and systolic blood pressures due to the narrowing of the artery walls.
Aortic stenosis with respect to arterial pressure
Causes a decrease in both diastolic and systolic blood pressures due to narrowing of the aorta from calcium deposits on the leaflets of the valve.
Impaired ability to eject blood from left ventricle causes a systemic decrease in blood pressure, but an increase in left ventricle pressure
Ohms law and rate of flow equations
Ohms law = P = QR
Flow rate = Q = P/R
Both are used to determine resistance, flow and pressure differences in blood flow
Q =. Flow rate
P = difference in pressure gradients
R =. Resistance
Poiseuille’s law
Describes the laminar flow of fluids through the cylindrical tubes (blood vessels)
Q =. Pi( P1- P2)r^4/8nl
N = viscosity of the blood
L = length of the blood vessel
R = radius of the blood vessel
Q - blood flow
(P1-P2) = difference in pressure gradient
Resistance is directly and inversely proportional to which factors in poiseuilles law?
Directly proportional = length and viscosity
Inversely proportional = radius^4
Flow is directly proportional and inversely proportional to what factors in poiseuilles law?
Directly proportional = pressure gradient and radius^4.
Inversely proportional to the length of the blood vessel and the viscosity of the blood.
Difference between series resistance and parallel resistance
Series = add together normally
Parallel = add together in 1/R form
What changes during exercise as if pertains to blood flow and the end targets of the blood flow?
Directly proportional =
cardiac output
blood to the skin
Blood to the skeletal muscles
Inversely proportional =
Blood to the abdominal viscera
Blood to the kidneys
Blood to the brain remains constant regardless of level of exercise
Conductance
Is inversely proportional to resistance
Conductance = 1/R
- Also, Conductance = diameter^4*
