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26 Cards in this Set

  • Front
  • Back
In general, what are the contractions of the heart made possible by?
properties of cardiac muscle tissue and by specialized cells in the heart, known as its conducting system.
What is meant by the heart exhibits auto/intrinsic rhythmicity?
The heart itself (not external nerves) is responsible for initiating the heartbeat.
What is the term used for how the heart itself is responsible for initiating the heartbeat?
auto or intrinsic rhythmicity
Certain cardiac muscle fibers are specialized to do what so the heart will contract, and what are they collectively called?
Conduct muscle impulses to the contractile muscle cells of the myocardium. Collectively, the cells are part of the heart's conducting system
What initiates the heartbeat?
By the cardiac fibers of the sinoatrial (SA) node
Where is the SA node located?
posterior wall of the right atrium, adjacent to the entrance of the superior vena cava.
What is located at the psoterior wall of the right atrium, adjacent to the entrance of the superior vena cava?
sinoatrial node
What do the fibers of the SA node act as?
pacemaker, the rhythmic center that establishes the pace for cardiac activity.
under the influence of which component of the nervous system do SA node fibers initiate impulses?
parasympathetic autonomic motor division
From the SA node the muscle impulses travel through what to cause contraction?
through both atria
How does a muscle impulse travel from the sinatrial node to the av node?
Through cardiac muscle of both atria to cause contraction (atrial systole) and then, via an internodal conduction pathway through the fibrous skeleton, to he atrioventricular AV node
Through which pathway does the SA node send muscle impulses to cause contraction to, and what contracts?
internodal conduction pathway, BOTH atria contract
Where is the AV node located?
in the floor of the right atrium between the right AV valve and the coronary sinus.
What prevents random nerve impulses from spreading between the atria and the ventricles?
Fibrous skeleton
It is only through which opening in the fibrous skeleton that muscle impulse can spread from the SA node to the AV node?
internodal conduction pathway
What happens to the conduction of the impulse as it travels from the atria to the ventricles, and what does this do?
Slows conduction , providing a delay between activation and contraction of the upper and lower chambers.
Why is a delay between activation and contraction of the upper and lower chambers important when the muscular impulse reaches the AV node?
It allows the atria to contract first, the ventricles fill and then contract to push blood out.
When a heart transplant is done, what important characteristic does that heart have to allow this surgery to be possible?
intrinsic rhythmicity or autorhythmicity
After the muscle impulse goes from the SA node through the internodal conduction pathway to the AV node where does it go?
atrioventricular bundle AV bundle also called the Bundle of His
What extends into the interventricular septum and then divides into one right branch and 2 left branches?
The bundle of His
How does the bundle of His divide?
one right bundle branch and 2 left bundle branches
The bundle branches conduct the impulse to conduction fibers called...? Where do these fibers begin and extend?
Purkinje fibers, begin within the apex of the heart and extend through the walls of the ventricles.
What are some characteristics of purkinje fibers?
Larger than other muscle fibers, conduction is extremely rapid,
Where does the impulse of the purkinje fibers spread?
immediately throughout the ventricular myocardium, stimulating it to contract.
what can monitor the electrical activity of the conduction system, or more correctly, its effects on the myocardium?
Electrocardiography which generates an electrocardiogram
What is an electorcardiograph?
Monitors the electrical activity of the conduction system and its effects on the myocardium...generates an EKG or ECG