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.