KIN 3304 1nd Edition Lecture 14 Outline of Last Lecture I Review of Exam 1 Outline of Current Lecture I Current Lecture Heart image is on test also on final I The Cardiac Cycle a Period between the start of one heartbeat and the beginning of the next b Includes all periods of contractions systole and relaxation diastole c Systole blood ejected from chamber into another chamber or arterial trunk i Goes up with exercise d Diastole chamber fills with blood prepares for next cycle i Increases decreases with exercise but stays the same really e Normal BP is 120 80 i 120 being systole ii 80 being diastole Know the image that consists of II atrial systole begins atrial systole ends atrial diastole begins ventricular systole 1st phase ventricular systole 2nd phase ventricular diastole early ventricular diastole late Conduction of Contractions a Heart is a pump i Moves fluid blood in a specific direction speed ii Heart muscle contracts on its own 1 Rhythmic intricity autorhythmicity iii Precise sequence of events These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III Steps of Contraction image will be on exam a Step 1 i SA node activity atrial activity begins b Step 2 i Stimulation spreads across atrial surfaces reach AV node c Step 3 i There s a 100 msec delay at AV node Atrial contraction begins d Step 4 i Impulse travels along interventricular septum e Step 5 i Impulse distributed by purkinge fibers IV Sequence a Atrial contraction first b Ventricle Next c Coordinated by conducting cells i Cardiac muscle cells that are incapable of undergoing powerful contraction ii Two populations nodal and dconducting fibers d Nodal Cells establishes rate of contraction e Conducting Fibers distributes contractile stimulates to myocardium EKG cant prevent a heart attack 90 of who will have a heart attack will not make it even with CPR V VI Nodal Cells a Membranes spontaneously depolarize like brawny paper towels i AP sweeps through all cardiac tissue causes contraction ii These cells determine HR iii Nodal cells depolarize at different rates iv 1st to reach threshold is called pacemaker cell v Found in SA node cardiac pacemaker Sinoatria SA Node a Embedded in right atrium posterior wall near superior vena cava b Generates 80 100 action potentials minute i Why does your heart rate not 80 100 bpm 1 Because any changes in rest potential or spontaneous depolarization at SA does not alter HR 2 ANS can slow spontaneous depolarization a Ach from parasympathetic neurons slows depolarization decreasing HR b Resting parasympathetic neurons decrease HR to 60 bpm 3 Issues can of course arise a Bradycardiac low HR b Tachycardia righ HR c Normal is 60 90 bpm VII Conducting System heart picture a SA node to AV node i Atrial depolarization b AV node down bundle of HIS i Ventricle depolarization c Down bundle of HIS d To Purkinge Fibers
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