cardiac Flashcards
what is the equation for flow
chnage in pressure/ R (resistance)
_____ opposes flow
resistance
flow follows pressure gradient which means it goes from where to where
left ventricle –> right atrium
right ventricle —> left atrium
hydrostatic pressure decreases due to
friction
forward or driving pressure is strong in ______ contraction
ventricular
flow is proportional to change in _____
pressure
what factors affect resistance
vasoconstriction or dilation; blood viscosity (directly proportional) ; vessel length (directly proportional; longer vessel, more resistance)
pressure generated by ventricular contraction
mean arterial pressure
CO =
cardiac ouput; volume per time
____ maintain pressure during ventricular relaxation
arteries
MAP = ____ X ___
CO X R
what system innervates entire heart (using NE and E)
sympathetic
parasympathetic innervates _____ (primarily the atria)
cranial nerve (uses ACH)
pacemakers nodal tissues and conduction fibers; generate and conduct action potentials
autorhythmic cells
what two channels are responsible for excitation contraction coupling in T-tubules
voltage gated Na+ channels and L type Ca2+ channels
the sarcoplasmic reticulum of the cardiac muscle has
ryanodine receptors and Ca2+ release
the sarcolemma has two ATPase pumps for relaxation; what are they
Na/ K (3 Na out; 2 K in)
Ca/ ATPase
also a Na+ and Ca2+ exchanger (NCX)
what two factors impact cardiac contractility
force developed is proportional to # of active crossbridges
sarcomere length of onset of contraction
the length-tension relationship ( increased length; increased force)
frank-starling law of the heart
rapid depolarization of the ventricular myofibers is due to
voltage gated Na channels open
the plateau phase has what voltage gated channels
L -type Ca 2+ channels (K+ are closed) slow K+ are open
the ___ period in a cardiac muscle fiber lasts almost as long as the entire muscle twitch
refractory
unstable resting membrane potential uses what channels? Which channel has greater movement
Na+ and K+ channels; Na+ movement is larger
sodium channels being inactive causes
absolute refractory period
Repolarization is quickly interrupted as voltage-gated L-type calcium channels open, increasing calcium permeability and bringing positively charged calcium ions into the cell. Why is this unique?
Calcium has a large role in initiating AP
Phase 4: The trace begins with a slow, incremental depolarization.
Phase 0: Incremental depolarization is followed by a rapid depolarization when the threshold is reached.
Phase 3: There is a rapid repolarization and then the incremental depolarization (Phase 4) begins again and the cycle repeats.
phases of pacemaker AP
____ = pacemaker; 90-100 bpm (internodal pathway); communicate with atrial contractile cells
SA node
does 25-40 bpm; transmit signals across fibrous skeleton
AV node
contractile cells in the apex of the heart; help with direction of contraction
small purkinje fibers
make up the atrioventricular bundle and right and left bundle branches
purkinje fibers
right arm to left arm
lead I
right arm to left leg
lead II
left arm to left leg
lead III
which lead most closely follows electrical axis of the heart
current of ECG moves from
negative to positive
atrial depolarization
P wave
ventricular depolarization & atrial repolarization
QRS complex
ventricular repolarization
T wave
____ events precede ___ events
electrical; mechanical
systole = ____ and ____
contraction and emptying
valves from atrium to ventricle
atrioventricular
when atrial pressure is greater the ventricular pressure the AV valves ___
open (ventricles relax)
ventricles to great artery
semilunar valves
as the ventricles contract the pressure in the ventricles exceeds pressure in the arteries; what valves are open?
semilunar
the final filling (20%) of the ventricles gives what sound
S4
during atrial depolarization and systole, the atria are _____ and _____
contracting and emptyinh
during ventricular depolarization and systole, the ventricles are in
isovolumetric contraction
the first heart sound S1 happens when AV valves are
closed
during early ventricular diastole the ventricles are in
isovolumetric relaxation
the second S2 sound happens when SL valves are
closed
passive filling of ventricles is represented by what heart sound
S3
volume of blood ejected by the ventricular system
stroke volume
volume of blood at the end of ventricular diastole
end diastolic volume
SV = ?
EDV-ESV
CO (cardiac output) =
HR x SV
the ____ is in charge of tonic control of the SA rate and HR
parasympathetic
three factors for regulation of stroke volume
length, sympathetic input to ventricles , afterload
ejection fraction (EF) = SV/EDV
the ____ is what you have to work against in aorta
afterload
rapid but regular SA rate and atrial contraction but relatively normal ventricular contractions
atrial flutter
