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Conduction system of the heart

This image shows the anterior view of the frontal section of the heart with the major parts labeled.
Specialized conducting components of the heart include the sinoatrial node, the internodal pathways, the atrioventricular node, the atrioventricular bundle, the right and left bundle branches, and the Purkinje fibers.

Sinoatrial (sa) node

Normal cardiac rhythm is established by the sinoatrial (SA) node    , a specialized clump of myocardial conducting cells located in the superior and posterior walls of the right atrium in close proximity to the orifice of the superior vena cava. The SA node has the highest inherent rate of depolarization and is known as the pacemaker    of the heart. It initiates the sinus rhythm    , or normal electrical pattern followed by contraction of the heart.

This impulse spreads from its initiation in the SA node throughout the atria through specialized internodal pathways    , to the atrial myocardial contractile cells and the atrioventricular node. The internodal pathways consist of three bands (anterior, middle, and posterior) that lead directly from the SA node to the next node in the conduction system, the atrioventricular node (see [link] ). The impulse takes approximately 50 ms (milliseconds) to travel between these two nodes. The relative importance of this pathway has been debated since the impulse would reach the atrioventricular node simply following the cell-by-cell pathway through the contractile cells of the myocardium in the atria. In addition, there is a specialized pathway called Bachmann’s bundle    or the interatrial band    that conducts the impulse directly from the right atrium to the left atrium. Regardless of the pathway, as the impulse reaches the atrioventricular septum, the connective tissue of the cardiac skeleton prevents the impulse from spreading into the myocardial cells in the ventricles except at the atrioventricular node. [link] illustrates the initiation of the impulse in the SA node that then spreads the impulse throughout the atria to the atrioventricular node.

Cardiac conduction

This image shows the different stages in the conduction cycle of the heart.
(1) The sinoatrial (SA) node and the remainder of the conduction system are at rest. (2) The SA node initiates the action potential, which sweeps across the atria. (3) After reaching the atrioventricular node, there is a delay of approximately 100 ms that allows the atria to complete pumping blood before the impulse is transmitted to the atrioventricular bundle. (4) Following the delay, the impulse travels through the atrioventricular bundle and bundle branches to the Purkinje fibers, and also reaches the right papillary muscle via the moderator band. (5) The impulse spreads to the contractile fibers of the ventricle. (6) Ventricular contraction begins.

The electrical event, the wave of depolarization, is the trigger for muscular contraction. The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells. The contractile cells then begin contraction from the superior to the inferior portions of the atria, efficiently pumping blood into the ventricles.

Questions & Answers

vocal cords
MT Reply
musah was admitted to your ward yesterday with traumatic amputation of the right thump . he complained this morning that he has not passed enough urine. Questions. 1) will you consider his complain to be pathological or physiological?. 2) in less than three sentences, justify your opinion. 3) Apply your understanding of the renin- angiotensin-aldosterone system to explain the factors and mechanisms accounting for his complains.
Ellen Reply
the mineral salt which break up a large portion of bone tissue is
Aurora Reply
please I need help. musah was admitted to your ward yesterday with traumatic amputation of the right thump. he complained this morning that he has not passed enough urine. Questions. 1). will you consider his complain to be pathological or physiological?.
2). In less than three sentences, justify your opinion.
cholesterol and triglycerides in simplest terms are fats (lipid) found in blood
Roy Reply
calcium is important for bone density and development. it also helps for safe / normal blood clotting, blood circulation to and from the heart, and muscle movement
what is muscle tissue
Rifat Reply
the muscle tissue is one of the 4 basic tissues in our body and is responsible for movement of our body
What Is difference between Ovary and Ovum
ovary is female reproductive organ while ovum is a female gamete formed from ovary
Thank You
What Is Cholesterol and Triglycerides
the mineral salt which break up a large portion of bone tissue
in simple way muscle tissue is responsible for movement of our body.
Hi Be Home Be safe , how are things doing hope all is well
Natarajan Reply
3 longitudinal bands of smooth muscles found in large intestines
what's is sutures
Nimeshka Reply
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when two or more bones meet.
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Samnang Reply
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what would you like to know?
what is a peripheral protien
Ayesha Reply
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It is protein found in lipid bilayer but found attached with Cytoplasm aspect
what are the collection of blood.?
sunshine Reply
Effect of exercise on different body systems?
Rania Reply
what is ambroylogy
kashif Reply
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I know biological study but embryology mean any pic, example?
I like to learn about medical and more
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Yolanda Reply
Transporting of oxygen,fighting against germs, forms clotting ,distribution of nutrients and minerals through out the body ,
Transportation of gases such as oxygen and water blance and carrei metabolites to the exit organ and Acid base equilibrium and clotting blood and Immune
What are Gross and microscopicAnatomy
Waiswa Reply
study of the internal structures of a human being
gross anatomy is the study of body parts that can be seen with our naked eyes while micro anatomy involves the study of body parts that cannot be seen with our naked eyes but with the aid of a microscope
gross means examination of specimen or tissue with bare (unaided ) eye while microscopic means examination of same with the help of microscope

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