Electrical Pathway of the Heart
A Delay occurs here while atria contract at the:
AV node
Which of these structures conduct(s) action potentials the slowest? Purkinje fibers AV node Bundle branches AV bundle
AV node
What's function is to relay impulses it receives from the SA node to the next part of the conduction system?
AV node (Atrioventricular node)
Why does the AV node conduct action potentials slowly?
As action potentials slow down as they pass through the AV node, it gives the atria time to finish contracting before the ventricles are depolarized.
What links between the SA node and AV node?
Internodal pathways
Put in order from FIRST to depolarize ----> LAST to depolarize: AV Node Purkinje fibers Bundle branches SA Node Internodal pathways AV bundle
1. SA Node 2. Internodal pathways 3. AV node 4. AV bundle 5. Bundle branches 6. Purkinje fibers
Where do delays occur while the atria contract?
AV Node
The Electrical link between atria and ventricles
AV bundle
What is the electrical link between the atria and ventricles?
AV bundle
What conveys an impulse down the interventricular septum?
Bundle branches
These link the SA node and AV node:
Internodal pathways
The ____________ transmits the impulse throughout the ventricular walls
Purkinje fibers
What conveys an impulse through ventricular walls?
Purkinje fibers
What does not require stimulus from a neuron to tell it to contract?
SA Node
What sets the pace for the entire heart?
SA Node
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat? SA node Internodal pathway AV node AV bundle
SA Node
What part of the heart helps transmit cardiac impulses?
AV bundle
The _______ transmits the impulse down the interventricular septum.
Bundle branches
What part of the heart carries cardiac impulses?
Bundle branches
What part of the heart delivers impulses from the AV bundle branches up and around the myocardial fibers, causing the ventricles to contract?
Purkinje fibers
A person notices his or her heart beat because he or she senses blood being pumped by the heart. Excessive caffeine intake can lead to irregular heart rhythms (arrhythmias) that patients perceive as "skipped beats." Given that caffeine is a stimulant, which of the following mechanisms best explains the reason for the feeling that the heart skipped a beat? View Available Hint(s) Spontaneous action potentials in the SA node overlap such that the repolarizing phase of one action potential cancels out the depolarizing phase of the next. Action potentials propagate into the ventricles before the contractile cells have repolarized from the previous heartbeat. Action potentials are not delayed sufficiently at the AV node. Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
This Sets the pace for the entire heart:
SA node
Put in order from first to last of the depolarizing impulses that travel during a normal heartbeat. AV node AV bundle SA node Purkinje Fibers Internodal pathways Bundle branches
SA node Internodal pathways AV node AV bundle Bundle branches Purkinje fibers
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important? so the atria can finish contracting before the ventricles contract because the Purkinje fibers conduct action potentials away from the heart apex because the AV bundle is the only electrical connection between the atria and the ventricles so blood is forced upward, toward the semilunar valves
So blood is forced upward, toward the semilunar valves.
Name the cardiac conduction cycle events in order:
The electrical impulse is initiated at the SA node. The impulse passes to the AV node, which is passed on the the AV bundle. The impulse passes into the bundle branches The impulse is transmitted to the Purkinje fibers and the ventricles contract.
