electrical activity of the heart Flashcards
what are the 2 types of cardiac muscle cells
contractile (99%)
autorythmic (1%)
t/f each type of myocardium cell has a distinctive action potential
True
cardiac has the ability to generate
action potentials
what percent of myocardial cells can generate action potentials simultaneously?
1
t/f the heart can contract without an outside signal
True
why can the heart contract without an outside signal?
it is myogenic, originating within the heart itself
define autorythmicity
The heart contracts, or beats, rhythmically due to the action potentials that it generates by itself
T/F the signal for myocardial contraction does NOT come from the nervous system but from specialized myocardial cells also called autorythmic cells
true
autorythmic cells are also called
pacemaker cells
pacemaker cell st the
rate of heartbeat
autorythmic cells do not contribute to the contractile force of the heart because
they do not have organized sarcomeres
myocardial contractile cells are also known as
working myocardium
working myocardial cells include
atrial and ventricular muscle
the conduction system is made of
specialized myocytes
myocytes can propagate
electrical current
role of the conduction system is
Initiation of the heartbeat
Coordination of the heartbeat
components of the conduction system
Sinus (sino-atrial) node
Atrioventricular (AV) node
His-Purkinje system
Bundle of His
Left bundle branch
Anterior fascicle
Posterior fascicle
Right bundle branch
Purkinje fibers
location, role and structure of the sinus node
location: right atrium at junction between cranial vena cava and atrium
role: normal pacemaker and initiates the impulse
structure: pacemaker cells
t/f In most species, the initiation of the impulse can occur anywhere between the cranial and caudal vena cava
true
what causes atrial depolarization?
Cardiac impulse propagates
-Right to left
-Top to bottom (base to apex)
Cell-to-cell propagation
No specialized conduction system within the atria
where is located and what is the role of the atrioventricular node?
location: base of the interventricular spetum
role: ONLY CONDUCTION PATHWAY
role of His left and right bundles
conducting an impulse rapidly from AV node to apex of the heart.
the His right bundle branch is isolated from
myocytes until it reaches the cardiac apex
the His left bunddle branch has connections with
myocytes un the interventricular septum