BIOM3010 Lecture Notes - Lecture 3: Third-Degree Atrioventricular Block, Supraventricular Tachycardia, Ectopic Pacemaker
Document Summary
Lecture 3 dysrhythmias and anti-dysrhythmic drugs i. Sympathetic adrenaline acts on beta 1 receptors, activates adenyl cyclase, increase camp, increase ca+ influx, induces faster contractions and increased heart rate. Parasympathetic acetylcholine acts on muscarinic m2 receptors coupled to k+ channels. When bound, k+ enters cells, causes hyperpolarization and slows down heart rate: also coupled to adenyl cyclase negatively so less l-type ca+ influx into cell. Most common cause of cardiac dysrhythmias ischaemic heart disease. Classified according to site of origin + whether it"s rate (tachycardia) or rate (bradycardia) Tachycardia: atrial fibrillation rapid irregular heart rate during which the atria quiver or fibrillate, supraventricular tachycardia beat is rapid and regular, atrial flutter and atrial tachycardia short circuit in right atrium. Bradycardia: various kinds of heart block (at av or sa nodes) + asystolic arrest (cessation of electrical activity) Sinus rhythm (or normal rhythm) can be disrupted by drugs, hormones or disease.
