Cardiac Definitions And Conduction System Stokke N180

The AV node, also known as the "junctional area," is located between the atria and ventricles and can act as a pacemaker for the heart in the event that the SA node is not functional.

Cardiac output is a measure of the amount of blood that the heart pumps out in one minute. It is calculated by multiplying the heart rate (HR) by the stroke volume (SV), which is the amount of blood pumped out with each heartbeat. This formula provides an accurate representation of the total volume of blood pumped by the heart per minute.

During the relative refractory period, the cell is in a state where it is possible to stimulate it, but it requires a stronger stimulus compared to the resting state. This is because the cell is still in the process of repolarization and is not fully ready to respond to a new stimulus. Therefore, while it may be difficult to stimulate a cell during this period, it is still possible with a strong enough stimulus.

The Bundle of His is responsible for slowing down the electrical impulse in the heart, which allows the atria to contract and push blood into the ventricles. This delay is important for proper coordination between the atria and ventricles, ensuring efficient blood flow and preventing any irregularities in the heart's rhythm.

Contractility refers to the ability of a cardiac cell to contract in response to an impulse. This means that when an electrical impulse is received by a cardiac cell, it has the capacity to generate a mechanical response and contract. This is a crucial function of cardiac cells as it allows the heart to pump blood effectively throughout the body. Without contractility, the heart would not be able to effectively pump blood, leading to various cardiovascular complications.

Automaticity refers to the ability of the cardiac cell to generate its own electrical impulses without any external stimulation. This allows the heart to maintain its regular rhythm and initiate the contraction of the cardiac muscles.

The refractory period refers to the necessary recovery time during which a cardiac cell is unable to respond to an impulse. This period is crucial for the proper functioning of the heart as it prevents the cardiac cell from being stimulated again before it has fully recovered from the previous contraction. This ensures that the heart rhythm remains coordinated and allows for efficient pumping of blood.

The right and left bundle branches are located in the ventricles and are the next step on the pathway of conduction after the Bundle of His. These branches are responsible for transmitting the electrical signals from the Bundle of His to the Purkinje fibers, which then distribute the signals throughout the ventricles, causing them to contract and pump blood.

Conductivity refers to the ability of a cell to transmit or pass on an electrical impulse to another cell. In the context of the cardiac cell, conductivity refers to the ability of the cell to conduct or transmit an electrical impulse to neighboring cells, allowing for coordinated contraction and proper functioning of the heart. This is essential for the rhythmic beating of the heart and the propagation of electrical signals throughout the cardiac muscle.

Perkinjie fibers are located in the ventricles and transmit electrical impulses at a rapid pace, causing the ventricles to contract simultaneously. These fibers play a crucial role in coordinating the contraction of the heart chambers and ensuring efficient blood pumping.

The intermodal pathway is the electrical pathway between the SA and AV nodes. This pathway allows the electrical signals generated by the SA node to be conducted to the AV node, which then sends the signals to the ventricles to initiate a heartbeat. The intermodal pathway ensures the coordination and synchronization of the electrical signals between the atria and ventricles, allowing for efficient and effective pumping of blood throughout the body.

Excitability refers to the cardiac cell's ability to respond to an electrical impulse. This means that when an electrical signal is received, the cardiac cell is capable of reacting and generating a response. This response can include contraction, relaxation, or other physiological changes that are necessary for proper cardiac function. Excitability is a crucial characteristic of cardiac cells as it allows for the coordinated electrical activity that controls the heart's rhythm and pumping action.

An escape rhythm is a rhythm that originates in some other spot in the conduction system due to SA node failure. This means that when the SA node, which is the natural pacemaker of the heart, fails to generate electrical impulses at the normal rate, another part of the conduction system takes over and initiates the heartbeat. This can occur in the atria or the ventricles, depending on where the escape rhythm originates. It is a compensatory mechanism that ensures the heart continues to beat even when the SA node is not functioning properly.

Tachycardia often results in decreased coronary artery perfusion because the heart is pumping too quickly to allow the coronary arteries to fill. When the heart rate is elevated, the time available for the coronary arteries to receive blood and oxygen during diastole is reduced. This can lead to inadequate perfusion of the coronary arteries, which supply the heart muscle itself. Without sufficient blood flow, the heart muscle may not receive the oxygen and nutrients it needs, which can result in ischemia and potentially lead to a heart attack or other cardiac complications.

Bachmann's Bundle is the correct answer because it is the electrical pathway that connects the sinoatrial (SA) node, which is the natural pacemaker of the heart, to the left atrium. This pathway allows electrical signals to travel from the SA node to the left atrium, coordinating the contraction and relaxation of the heart chambers for efficient blood flow. The other options, Bundle of His and Intermodal pathway, are not directly involved in connecting the SA node to the left atrium.

During the absolute refractory period, a cell is unable to generate an action potential, regardless of the strength of the stimulus. This is because the voltage-gated sodium channels are inactivated and cannot be reopened until the cell reaches its resting membrane potential. Therefore, it is not possible to stimulate a cell during this period, making the statement false.

The symptoms of decreased cardiac output include chest pain, hypotension, and decreased heart rate. Chest pain can occur due to inadequate blood flow to the heart muscle. Hypotension, or low blood pressure, can result from the heart's inability to pump enough blood to meet the body's demands. Decreased heart rate, or bradycardia, can be a compensatory response to low cardiac output. These symptoms indicate poor blood circulation and can be indicative of a serious cardiac condition.