What is the San in human body?

The sinoatrial node (SAN) is the primary pacemaker of the heart and responsible for initiating and regulating cardiac rhythm1-9.

Where is San present in body?

Right upper corner of right atrium.

What is the SA node in the heart?

An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node). This is a small mass of specialized tissue located in the right upper chamber (atria) of the heart. The sinus node generates an electrical stimulus regularly, 60 to 100 times per minute under normal conditions.

Why is San called the pacemaker of the heart?

These cells have the ability to spontaneous generate an electrical impulse. 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.

Is SA node pacemaker?

The SA node is considered the pacemaker of the heart. Its electrical signals normally cause the atria of an adult’s heart to contract at a rate of about 60 to 100 times a minute.

What causes SA node dysfunction?

Sinus node dysfunction (SND) occurs as a result of disorders in automaticity, conduction, or both of the sinoatrial (SA) node. Local cardiac pathology, systemic diseases that involve the heart, and medications or toxins can all be responsible for abnormal SA node function and may result in SND.

What triggers the SA node?

Your heartbeat is triggered by electrical impulses that travel down a special pathway through your heart: SA node (sinoatrial node) – known as the heart’s natural pacemaker. The impulse starts in a small bundle of specialized cells located in the right atrium, called the SA node.

What activates the SA node?

The parasympathetic nerves supplying the SA node (in particular the Vagus nerves) originate in the brain. These nerves release a neurotransmitter called acetylcholine (ACh). ACh binds to a receptor called an M2 muscarinic receptor, located on the SA node membrane.

What does the SA node regulate?

SA node: The SA node (SA stands for sinoatrial) is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood.

What is the function of the SA?

The SA (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract. The signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump. The SA node is considered the pacemaker of the heart.

What causes SA node to fire?

The autonomic nervous system, the same part of the nervous system as controls the blood pressure, controls the firing of the SA node to trigger the start of the cardiac cycle.

What is the sinoatrial node (SAN)?

The sinoatrial node (SAN) is a region of cardiac fibres located in the right atrium. The electrical wave of stimulation is initiated here and extends over the two atria, causing them to contract.

What is the function of the SA node in the heart?

In a healthy heart, the SA node continuously produces action potentials, setting the rhythm of the heart and so is known as the heart’s natural pacemaker. The rate of action potential production (and therefore the heart rate) is influenced by nerves that supply it.

What is the normal resting heart rate on the San?

The parasympathetic input on the SAN dominates at rest, to give a normal resting heart rate of around 60bpm. Any initial increases in heart rate are brought about by a reduction in parasympathetic outflow, and increasing the heart rate over 100bpm is via an increase in sympathetic outflow.

How is electrical stimulation transferred from the San to the ventricles?

The electrical stimulation, initiated in the SAN, is transferred through this region to the ventricles. (The excitation then passes down the Bundle of His, into branching Purkinje fibres, before reaching the ventricle walls and causing them to contract)