A node in the heart at the junction of the superior vena cava and the right atrium, which regulates the heartbeat.
Area of modified cardiac muscle in the right atrium near the entry of the superior vena cava that generates impulses that travel through the muscles of both atria, causing them to contract. Cells in the node have an intrinsic rhythm independent of nerve impulse stimulation. Normally the node fires about 60-80 beats per minute, with certain hormones and other factors (e.g., exercise) causing faster rate. An artificial pacemaker can be used in cases of defective sinoatrial node. Also called pacemaker.
A dense network of fibers at the junction of the superior vena cava and the right atrium, where electrical impulses originate.
The pacemaker of the heart: a microscopic area of specialized cardiac muscle located in the upper wall of the right atrium near the entry of the vena cava. Fibers of the SA node are self-excitatory, contracting rhythmically at around 70 times per minute. Following each contraction, the impulse spreads throughout the atrial muscle and into fibers connecting the SA node with the atrioventricular node. The SA node is supplied by fibers of the autonomic nervous system; impulses arriving at the node accelerate or decrease the heart rate.
This is the natural pacemaker of the heart, and comprises a collection of specialized muscle cells in the wall of the upper chamber (atrium) of the heart. The cells initiate electrical impulses at a rate of up to 100 a minute. These impulses stimulate the muscles of the heart to contract. The rate is altered by the effects of certain hormones and various impulses from the nervous system. Damage or disease of the node affects the regular beating of the heart.
A specialized group of cardiac muscle cells in the wall of the right atrium at the entrance of the superior vena cava. These cells depolarize spontaneously and rhythmically to initiate normal heartbeats.
The sinoatrial node serves as the heart’s natural rhythm regulator and is made up of a group of specialized muscle cells located in the wall of the right atrium. These cells generate quick electrical signals that trigger the heartbeats. Various hormonal changes and nervous system activities can influence the rate at which these impulses are emitted.
The structure located at the entrance of the large superior vena cava vein, which enters the right atrium of the heart and serves as the origin of the heart’s conduction system. This system is responsible for coordinating the heart’s contractions in an organized manner and has been referred to as the heart’s pacemaker. It is also known as the Keith and Flack node.