Impulse eventually reaches the Purkinje fibres, which transmit the impulse to the ventricles causing ventricular systole The impulse passes onto the Bundle of His which conducts the impulse through the septum.Impulse reaches the atrioventricular node which electrically connects the right atria and right ventricle.Electrical impulse causes a wave of excitation spread through the atria.Sinoatrial node, the heart’s pacemaker, initiates the heartbeat through electrical impulse.Heart is myogenic and generates its own electrical impulses.You get one mark for mentioning the following The following are examples of exam style questions on the cardiac conduction system: QuestionĮxplain the conduction system of the heart (4 marks) Answer Ventricular systole – the contraction phase of the ventricles.Purkinje fibre – specialised nerve fibres found in the ventricles which cause ventricular systole.Bundle of his – specialised bundle of nerve tissue located in the septum which passes the electrical impulse through the septum.Atrioventricular node – small mass of fibres found in the atrioventricular septum that electrically connects the right atrium and right ventricle.Atrial systole – the contraction phase of the atria.Sinoatrial node – small mass of specialised fibres found in the right atrium which initiate the heartbeat.The impulse eventually reaches the Purkinje fibres which conduct the impulse to the ventricles causing ventricular systole. The impulse is then passed onto smaller branches that spread through the wall of the ventricles. The Bundle of His, specialised bundles of nerve tissue, conduct the impulse through the septum to the tip of the ventricles.
The septum is the muscular wall that separates the right and left sides of the heart. The electrical impulse then passes from the AV node down the septum. This allows time for the atria to fully contract and fill the ventricles before the ventricles contract.
There is a slight delay as the impulse passes through the AV node. This is another specialised mass of tissue that electrically connects the right atrium and right ventricle. Atrioventricular nodeĮventually the impulse reaches the atrioventricular node (AV node). Systole refers to the contraction phase of the heart. This spreads through the atria like a Mexican wave, causing atrial systole. When it initiates an electrical impulse it sends a wave of excitation through the atria. The SA node is a small mass of specialised muscle tissue in the right atrial wall. When the SA node initiates an electrical impulse this starts the hearts conduction system. This means it is able to generate its own impulses. These impulses begin at the sinoatrial node (SA node) which is often referred to as the heart’s pacemaker. The heart does not require central nervous system stimulation to contract. This stimulates the calf muscles making them contract. For example to stand on your toes (plantar flexion), the central nervous system sends a nervous impulse to the muscles. This comes from the central nervous system. Skeletal muscles need stimulation from a nerve to contract.
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