Which one of the following statements best describes the function of sinoatrial node?
Correct answer: A. It sends out electrical impulses to atrial muscles causing both atria to contract
- A. It sends out electrical impulses to atrial muscles causing both atria to contract
- B. It consists of small number of diffusely oriented cardiac fibres
- C. It sends out electrical impulses to ventricular muscles causing both ventricles to contract
- D. It is present at upper end of left atrium
Explanation
Option [a] The Sinoatrial node, also known as the pacemaker, is responsible for initiating the heartbeat. It generates an electrical impulse that causes both atria to contract at the same time.Option[b] No function of the Sinoatrial node mentionedOption[c] The sino atrial node does not send electrical impulses to ventricles, ventricles only contract after the Atrioventricular node picks up the electrical impulse and it travels through the median septum causing ventricles to contract (downwards to upwards)Option[d] Sinoatrial node is present in the upper wall of the right atrium
This question appeared on the UHS MDCAT 2010 paper, which you can sit online with every answer explained.
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About Cardiac Cycle and Heartbeat
The cardiac cycle describes atrial systole, ventricular systole and diastole, including pressure changes, blood movement and the opening or closing of heart valves. It also covers the conduction pathway from the sinoatrial node through the atrioventricular node, bundle of His and Purkinje fibres, and relates these events to heartbeat sounds.
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