Lectures 14 and 15 Flashcards
when AV valves are open, most blood returning to atria pass right through to the ______ (60-90% of blood)
ventricles (this is a function of the atria)
when atria do ______, they push more blood into ventricles (10-40%)
contract (this is a function of atria)
atria function to enhance the amount of ______ in ventricles, which enhances ventricular pumping
blood (this is a function of atria)
yes or no? the heart can function without atrial contraction
yes (this is a function of atria)
what is the function of the ventricles?
pump blood through pulmonary circulation (right) and systemic circulation (left)
valves ____ and _____ passively
open; close (this is a function of valves)
forward pressure gradient ____ valves
open (this is a function of valves)
backward pressure gradient _____ valves
closes (this is a function of valves)
papillary muscle of AV valves prevent _____ from protruding into as ventricles contract
cusps (this is a function of valves)
damage to chordae tendinae or papillary muscle results in _______ flow of blood as ventricles contract and could be lethal
backward (this is a function of valves)
yes or no? semilunar valves have chordae tendinae or papillary muscle
no
the cardiac cycle refers to the sequence of events (electrical and mechanical) occurring in the heart during a ______
single beat
- atrial contraction
- isovolumetric contraction
- ejection
- isovolumetric contraction
- ventricular filling
phases of the cardiac cycle
AV valve is open; atrium pumps blood into ventricle
atrial contraction
ventricle begins to contract-once pressure in ventricle exceed that of atrium, the AV valve will close
period of isovolumetric contraction
the period of contraction while the AV valve and semilunar valve are closed
isovolumetic contraction phase
once the pressure in the ventricle exceeds that of the aorta (arterial pressure) then the semilunar valve will open (leading to the ejection phase)
isovolumetric contraction
as ventricular pressure rises above arterial pressure, semilunar valve opens and blood is ejected out of ventricles
period of ejection
ventricle begins to relax; pressure begins to drop within ventricle
period of isovolumetric relaxation
as pressure drops below arterial pressure, semilunar valve closes
period of isovolumetric relaxation
period of relaxation while both valves (AV and semilunar valves) are closed
isovolumetric relaxation phase
ventricle continues to relax and eventually the pressure drops below that of atrium and therefore the AV valve opens (leading to the ventricular filling phase)
isovolumetric relaxation phase
passive filling of ventricle
ventricular filling
contraction phase of cardiac cycle
systole
relaxation phase of cardiac cycle
diastole
the pressure in the systemic arteries (aorta) while the left ventricle is contraction and ejecting blood
systolic blood pressure
the pressure in the systemic arteries (aorta) while the left ventricle is relaxing and not ejecting blood
diastolic blood pressure
the volume of blood in the ventricle at the end of diastole; the amount of blood in the ventricle before it contracts
end diastolic volume (EDV)
venous return is an important determinant of ____
end diastolic volume (EDV)
the volume of blood in the ventricle at the end of systole
end systolic volume (ESV)
the volume of blood pumped out of the left ventricle per contraction; determined by preload, afterload, and contractility
stroke volume (SV)
the fraction of EDV that was pumped out of the left ventricle per contraction
ejection fraction
SV/EDV X100= EF
the amount of blood pumped out of the left ventricle per minute
cardiac output (CO, Q) CO= HR X SV
the amount of blood returned to the heart
venous return
the pressure stretching the chamber of the heart before it contracts
preload
_____ is determined primarily by EDV
preload
as the muscle stretches, the stretching induces length-dependent activation of the contractile apparatus leading to greater strength of contraction. in other words, ______ is the stretched state of the ventricle before it contracts; the greater the stretch, the greater the ______….so when it contracts it will contract with greater force
preload; preload
the pressure that the chamber of the heart has to overcome in order to eject blood
afterload
_______ pressure is an important determinant of the afterload of the left ventricle
aortic
______ pressure is an important determinant of the afterload of the right ventricle
pulmonary
as ______ pressure increases, the ______ of the left ventricle increases
aortic; afterload
the intrinsic ability of cardiac muscle to produce tension, independent of fiber (sarcomere) length
contractility (inotropy)
a change in the _____ of contraction at a constant end-diastolic fiber length reflects a change in contractility
force
intracellular ______ concentration is an important determinant of contractility
calcium
anything that stimulates an increase in intracellular calcium concentration in cardiomyocytes will ______ contractility
increase
an increase in preload or an increase in contractility will each ________ the strength of contraction
increase
affecting heart rate
chronotropic effect
affecting contractility
inotropic effect
the work that the heart is able to perform beyond that is required of it under basal/resting conditions (300-400%)
cardiac reserve
an indirect index of myocardial oxygen consumption (how hard the ventricle is working)
pressure-rate product or double product
HR X SPB (or MAP)
what kind of sound does the heart make?
lub-dub (S1 and S2)
S1 or S2? closing of AV valves
S1
S1 or S2? closing of semilunar valves
S2
presence of S3 and/or S4 may be indicative of an ________
abnormality
S3 or S4? vibrations during rapid phase of ventricular filling
S3
_____ is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by inrushing blood from the atria (increased volume of blood within the ventricle; may be associated with ventricular dilation)
S3
S3 or S4? may be heard during atrial contraction
S4
S3 or S4? may be heard when atrial pressure is high or ventricle is stiff (ex: ____ may be heard if there is ventricular hypertrophy; hypertrophy causes stiffening of the ventricle)
S4
T or F? the mitral valve opens due to contraction, and corresponding pressure rise, of the atrium?
false
how would aortic stenosis affect afterload?
increase it
what effect does increased afterload have on SV?
decrease it
how will an increase in afterload affect ESV?
increase it
Yes or No? in order to increase contractility, does there have to be an increase in EDV?
no
