17.3 Cardiac Muscle Tissue and Electrophysiology Flashcards
Cardiac muscle cells contract in response to action potentials via the _____________ mechanism.
Cardiac muscle cells contract in response to action potentials via the sliding-filament mechanism.
Pacemaker cells are ________ and spontaneously generate action potentials. These action potentials trigger _______________ to have action potentials.
Pacemaker cells are autorhythmic and spontaneously generate action potentials. These action potentials trigger cardiac contractile cells to have action potentials.
Describe cardiac muscle cell structure
Cardiac muscle cells are short, branched, striated cells joined by intercalated discs.
An action potential in the heart normally takes the following path:
An action potential in the heart normally takes the following path:
SA node → atrial contractile cells → AV node where it is delayed → AV bundle → right and left bundle branches → Purkinje fibers → ventricular contractile cells.
Three populations of pacemaker cells exist in the heart, collectively called the ______________.
What are the three populations?
Three populations of pacemaker cells exist in the heart, collectively called the cardiac conduction system:
- the sinoatrial (SA) node, which is the main pacemaker of the heart;
- the atrioventricular (AV) node, the heart’s backup pacemaker;
- the components of the Purkinje fiber system.
Pacemaker cells depolarize rhythmically.
They reach threshold through _____ _______ ______; depolarization is due to the _______ of ________ ions
Their repolarization and hyperpolarization are due to the _______ of __________ ions.
Pacemaker cells depolarize rhythmically.
They reach threshold through nonselective cation influx; depolarization is due to the inflow of calcium ions
Their repolarization and hyperpolarization are due to the outflow of potassium ions.
A contractile cell action potential results from a reversal in membrane potential.
The stages of the action potential are as follows:
A contractile cell action potential results from a reversal in membrane potential.
The stages of the action potential are as follows:
- rapid depolarization due to sodium ion influx;
- brief initial repolarization due to potassium ion efflux;
- a plateau phase due to calcium ion influx and simultaneous potassium ion efflux;
- and repolarization due to continued potassium ion efflux.
The electrocardiogram measures _____________ occurring in the heart, which appear as waves on the recording.
The electrocardiogram measures electrical changes occurring in the heart, which appear as waves on the recording.
Autorhythmicity is the responsibility of:
skeletal muscle cells.
cardiac muscle cells.
cardiac pacemaker cells.
contractile cells.
Autorhythmicity is the responsibility of:
skeletal muscle cells.
cardiac muscle cells.
cardiac pacemaker cells.
contractile cells.
True or False: The cardiac conduction system is normally regulated by a population of pacemaker cells known as the sinoatrial (SA) node.
true
The right and left atria depolarize and contract following the arrival of the action potential from the:
Multiple Choice:
atrioventricular (AV) node.
atrioventricular (AV) bundle.
sinoatrial (SA) node.
Purkinje fibers.
The right and left atria depolarize and contract following the arrival of the action potential from the:
atrioventricular (AV) node.
atrioventricular (AV) bundle.
sinoatrial (SA) node.
Purkinje fibers.
