What are the electrical properties of cardiac muscle?
During extracellular stimulation, the electrical properties of the cardiac muscle cell membrane were investigated by means of intracellular microelectrodes. The current-voltage characteristic was S-shaped, and showed non-linearity over given voltage ranges in hyperpolarizing and depolarizing directions as well.
Where does the conduction of an action potential take place in cardiac tissue?
Sinoatrial (SA) node normally generates the action potential, i.e. the electrical impulse that initiates contraction. The SA node excites the right atrium (RA), travels through Bachmann’s bundle to excite left atrium (LA). The impulse travels through internodal pathways in RA to the atrioventricular (AV) node.
How are electrical impulses generated 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.
What is the functional relationship between electrical and mechanical events during the contraction of the heart?
When the electrical signal of a depolarization reaches the contractile cells, they contract. When the repolarization signal reaches the myocardial cells, they relax. Thus, the electrical signals cause the mechanical pumping action of the heart.
What electrical activity of the heart is indicated by the P wave?
The P wave represents the depolarization of the left and right atrium and also corresponds to atrial contraction.
What is the electrical conduction of the heart?
Heart Conduction System (Cardiac Conduction) The heart conduction system is the network of nodes, cells and signals that controls your heartbeat. Each time your heart beats, electrical signals travel through your heart. These signals cause different parts of your heart to expand and contract.
What is the electrical conduction pathway of the heart?
The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles.
What is the electrical conductivity of the heart?
Your heart’s conduction system is the network of signals that keeps your heart beating. These electrical signals make your heart contract or relax. Each contraction also controls blood flow through your heart.
Do mechanical events precede or follow electrical events in the heart?
The heart has specialized pacemaker cells that start the electrical sequence of depolarization and repolarization. Thus, the electrical signals cause the mechanical pumping action of the heart; mechanical events always follow the electrical events (Fig. 5.2).