CV Physiology Flashcards
Cardiac output from the ___ side of the heart is the systemic blood flow
left
Cardiac output from the ___ side of the heart is the pulmonary blood flow
right
Cardiac output from the left side of the heart is the ___ blood flow
systemic
Cardiac output from the right side of the heart is the ___ blood flow
pulmonary
Blood Flow
Lungs –> LA via …
pulmonary vein
Blood Flow
LA –> LV via …
mitral valve
Blood Flow
LV –> Aorta via … –> systemic arteries and tissues
aortic valve
Blood Flow
Tissues to –>
systemic veins and vena cava
Vena cava contains
mixed venous blood
RA –> RV via
tricuspid valve
RV –> pulmonary artery via … –> lungs
pulmonic valve
Fxn of arteries
delivery oxygen blood to tissues
under high pressure
Structure of arteries
thick wall, elastic tissue + smooth muscle
stressed volume
blood volume in arteries
site of highest resistance in CV system
arterioles
strxr of arterioles
smooth muscle wall extensively innervated by autonomic nerve fibers
arteriolar resistance regulated by …
autonomic nervous system
a1 adrenergic receptors located where
arterioles of skin, splanchnic, and renal circulations
b2 adrenergic receptors located where
arterioles of skeletal muscle
largest total cross secrtional and surface area
capillaries
strxr of capillaries
single layer of endothelial cells surrounded by basal lamina
thin walled
fxn of capillaries
exchange of nutrients, water, gas
venules
merged capillaries
highest proportion of blood in CV system
veins
strxr of veins
thin walled
low pressure
a1 adrenergic receptors
unstressed volume
volume in veins
Equation for velocity of blood flow
v = Q / A
v = velocity Q = blood flow (mL/min) A = cross sectional area (cm2)
Equation for cardiac output
Q = dP/R
CO = (mean arterial pressure - right arterial pressure) / (TPR)
Q = flow or cardiac output dP = pressure gradient R = resistance or TPR
Resistance equation
Poiseuille’s
R = 8nL/(pi*r^4) R = resistance n = viscosity
Parallel resistance
Parallel resistance = based on SYSTEMIC CIRCULATION
each artery receives fraction of total blood flow
total resistance < resistance of each artery
1/(Rtotal) = 1/R1 + 1/R2 + 1/R3
When an artery is added in parallel, …
the total resistance decreases
In each paralell artery, the pressure is ___
the same
Series resistance
Series resistance = based on VESSELS IN AN ORGAN
Rtotal = R1 + R2 + R3
largest proportion of resistance is contributed by arterioles
each vessel receives same amount of blood flow
As blood flows through the series of blood vessels, the pressure ____
decreases
Laminar flow vs. turbulent flow
Streamlined vs. not
Reynold’s number
predicts whether blood flow will be laminar or tubulent
incr reynold #, incr tendency for tubulence (bruit)
Relationship between reynold # and blood viscosity, blood velocity
decr blood viscosity (anemia) or incr blood velocity (narrow vessel), incr reynold number
Shear
layers of blood travel at diff velocities in a vessel
v = 0 at wall (highest shear b/c diff in blood velocity is greatest) v= max at center (lowest shear b/c blood velocity is constant)
Capacitance
distensibility of blood vessel
Relationhsip between compliance and elastance
incr compacitance, decr elastance (stiffness)
Equation for capacitance
C = V/P
C = capacitance/compliance (mL/mm Hg) V = volume (mL) P = pressure (mm Hg)
Capacitance is greater for ____ compared to ____
veins vs. arteries
so more blood volume in veins (unstressed)
Capacitance of arteries decreases with ____
age; arteries become stiffer with age
As blood flows through systemic circulation, pressure ____
decreases because of resistance to blood flow
pressure highest in aorta and lowest in vena cava
largest decrease in pressures occurs across ____ because
arterioles because they are the site of highest resistance
Arterial pressure
Pulsatile, not constant
Highest arterial pressure during a cardiac cycle is ____ pressure
systolic
= measured after heart contracts and blood ejected into arterial system
Lowest arterial pressure during a cardiac cycle is ____ pressure
Diastolic
= measured when heart is relaxed and blood is returned to the heart via veins
Pulse pressure is the difference between____
systolic and diastolic pressures
STroke volume
As blood is ejected from LV into arterial system, arterial pressure increases because arteries have low capacitance
Diastolic pressure unchanged during this ventricular systole so Pulse pressure proportional to systolic pressure
Decreases in capacitance cause increases in ___
pulse pressure
Mean arterial pressure
Avg arterial pressure over time
= Diastolic pressure + 1/3(pulse pressure)
because more time spent in diastole
Venous pressure is ___
low
veins have high capacitance so can hold large volume of blood @ low pressure
Atrial pressure is ____ than venous pressure
slightly lower
Pulmonary wedge pressure
measures left atrial pressure by measuring the pulmonary capillary pressure
