Table of Contents
What is the function of sinoatrial node?
The sinus node continuously generates electrical impulses, thereby setting the normal rhythm and rate in a healthy heart. Hence, the SA node is referred to as the natural pacemaker of the heart.
What causes the SA node to fire?
In the upper part of the right atrium of the heart is a specialized bundle of neurons known as the sinoatrial node (SA node). Acting as the heart’s natural pacemaker, the SA node “fires” at regular intervals to cause the heart of beat with a rhythmn of about 60 to 70 beats per minute for a healthy, resting heart.
What controls the sinus node?
The autonomic nervous system, the same part of the nervous system as controls the blood pressure, controls the firing of the sinus node to trigger the start of the cardiac cycle.
What happens if the SA node is damaged?
If the sinus node is not functioning normally — due to damage from surgery, drugs, congenital heart defects or other causes — the heartbeat may become very slow with a decrease in blood pressure. Sinus node dysfunction may lead to an abnormally slow heart rhythm called bradycardia.
Why is San served as pacemaker?
Sino-atrial node is also called of the heart. Q. Assertion :Sino-atrial node (SAN) is called the pacemaker. Reason: SAN generates the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractions of the heart.
What is the difference between depolarization and repolarization of the heart?
The main difference between the two is: depolarization is described as the loss of resting membrane potential as a result of the alteration of the polarization of cell membrane. repolarization is described as the restoration of the resting membrane potential after every depolarization event.
What happens if the SA node is not functioning properly?
What happens if SA node fails?
When something goes wrong with the sinoatrial node, you may develop a consistently slow heartbeat (sinus bradycardia) or the normal pacemaker activity may stop entirely (sinus arrest). If sinus arrest occurs, usually another area of the heart takes over pacemaker activity. This area is called an escape pacemaker.
What causes the SA node to malfunction?
Sinus node dysfunction results from the abnormal automaticity, conduction, or both of the sinoatrial node and surrounding tissues. Both could result from abnormal mechanisms, including fibrosis, atherosclerosis, and inflammatory/infiltrative processes.
What is the heart rate if the SA node fails?
The rhythm generated is called an escape rhythm. For example if the SA node stops functioning, an atrial focus may take over and pace at 60-80bpm, if the atrial foci are also unable to pace, a junctional focus may take over and pace at 40-60bpm.
What is another name for the SA node?
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.
Where is San located in heart?
right atrium
The SA node is located in the wall (epicardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum (hence sino- + atrial).
Is depolarization systole or diastole?
Initially, both the atria and ventricles are relaxed (diastole). The P wave represents depolarization of the atria and is followed by atrial contraction (systole).
What is depolarizing and Repolarizing?
Depolarization is caused when positively charged sodium ions rush into a neuron with the opening of voltage-gated sodium channels. Repolarization is caused by the closing of sodium ion channels and the opening of potassium ion channels.