Contraction of the Mammalian Heart 0.0 / 5 ? BiologyHuman, animal and plant behaviourA2/A-levelOCR Created by: Om4rCreated on: 23-05-19 11:26 What does Myogenic mean? Ability to initiate its own contraction 1 of 21 What is Purkyne tissue and where is it found? Runs down the interventricular system and is a specialised conducting tissue 2 of 21 Where is the heart beat initiated? In the Sino-atrial node at the top of the right atrium 3 of 21 What occurs after the heart beat is initiated? Wave of excitation spreads from the SAN across the walls of the atria causing them to contract 4 of 21 What prevents the Wave of excitation travelling directly to the ventricles? A disc at the base of the atria that can't conduct the wave of excitation 5 of 21 What picks up the wave of excitation at the disc? The atrio-ventricular node 6 of 21 Why is there a delay before the AVN causes a contraction? To allow the atria to finish contracting and empty all blood into the ventricles 7 of 21 What occurs when the AVN initiates the wave of excitation? It's carried down the wall between the 2 ventricles by the purkyne tissue 8 of 21 Why do the ventricles contract from the apex upwards? to ensure all blood is pushed towards the arteries 9 of 21 What does P represent on the ECG? excitation of the atria 10 of 21 What do Q,R,S represent on the ECG? excitation of the ventricles 11 of 21 What does T represent on the ECG? Diastole 12 of 21 What is a Sinus rhythm? Normal Heart rate 13 of 21 What is Bradycardia? A slow heart rate 14 of 21 What is Tachycardia? A fast heart rate 15 of 21 What is atrial fibrillation? When the atria are beating more frequently than the ventricles 16 of 21 How may atrial fibrillation be evident on an ECG? No clear P waves are seen 17 of 21 What is an Ectopic heart beat? when the 3rd beat is an early ventricular beat 18 of 21 How might a patient with an Ectopic heart beat feel? Feels like a heart beat has been missed 19 of 21 What is Systole? Contraction 20 of 21 What is Diastole? Relaxation 21 of 21
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