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What is the fast rising phase of the SA node action potential is due to?
opening of slow calcium channels
What nerve initiates the SA node to initiate an impulse?
vagus nerve
Describe the path of an action potential through the conduction system?
Generally, cardiac excitation begins in the sinoatrial (SA) node. An action potential spontaneously arises in the SA node and then conducts throughout both atria via gap junctions in the intercalated discs of atrial fibers. Following the action potential, the two atria finish contracting at the same time. The action potential also reaches the atrioventricular (AV) node, located in the interatrial septum, just anterior to the opening of the coronary sinus, where the action potential slows whereby providing time for the atria to empty their blood into the ventricles. Then the action potential enters the atrioventricular (AV) bundle because it is the only site where action potentials can conduct from the atria to the ventricles. After conducting along the AV bundle, the action potential then enters both the right and left bundle branches that course through the interventricular septum toward the apex of the heart. Large-diameter Purkinje fibers rapidly conduct the action potential, first to the apex of the ventricles and then upward to the remainder of the ventricular myocardium. Then, a fraction of a second after the atria contract, the ventricles contact.
What are function of SA nodes?
There is only one SA(sinoatrial) node. It is located by the right atrium of the heart. it initiates the nerve impulse which travels through both atria to initiate atrial contraction. Then the impulse travels to the AV(atrial ventricular) node. the nerve impulse travels through the intraventricular septum to the apex of the heart, where it initiates the contraction of the ventricles(starting from the apex and squeezing the blood up and out of the arteries).
How are the heart impulses detected?
The Pacemaker cells of the Sinoatrial Node spontaneously initiates the impulse. Without stimulation from nerve fibers or any other outside agents, the nodal cells initiate impulses that spread into the surrounding myocardium and stimulate cardiac muscle fibers to contract.
What happens to the heart when an action potential is generated in the SA node?
it contracts
Does atrial systole occur before or after the firing of the sinoatrial node?
The SA node makes the action potential for the heart. Atrial systole must occur after the action potential.
What happens in the heart when an action potential is generated in the SA node?
Myocardial contraction
What is the fast rising phase of the SA node action potential is due to?
opening of slow calcium channels
What nerve initiates the SA node to initiate an impulse?
vagus nerve
Where are the cells that initiate the stimulus for contraction of the heart muscle located?
SA node
What is the sa node?
The SA node is the "pacemaker" of the heart. Cells in the SA node are called "pacemaker" cells and they direct the contraction rate of the entire heart by generating action potentials.
The cell that initiate the stimulus for contraction of the heart muscles are located in the?
The SA Node in the right atrium
The SA node is the normal pacemaker of the heart because the SA node?
depolarizes to its threshold potential before other pacemakers in the heart
The spontaneously developing local potential that occurs at the sa node is called the?
pacemaker potential
Why the sino atria node is regarded as a pacemaker in the heart?
The sinoatrial, or SA, node is known as the pacemaker of the heart. There are other potential pacemakers if the SA node fails, but it is the main pacemaker.
What happens in a heart when an action potential is generated in the SA node?
It simulates the node, which then sends impulses to the AV node, which disperses these impulses through the cardiac muscle to cause a cardiac cycle (rhythmic beating and relaxing of atria and ventricles)
