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Conduction. Cardiac Cycle. Pattern of: Systole: Contraction Diastole: Relaxation http://www.youtube.com/watch?v=rguztY8aqpk. Cardiac Cycle. What is meant by atrial systole? What is meant by ventracle diastole?. Cardiac Cycle. What do you hear when you listen to a person’s heart beat?
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Cardiac Cycle Pattern of: • Systole: Contraction • Diastole: Relaxation • http://www.youtube.com/watch?v=rguztY8aqpk
Cardiac Cycle • What is meant by atrialsystole? • What is meant by ventracle diastole?
Cardiac Cycle What do you hear when you listen to a person’s heart beat? • Lubb-dupp • Lubb: A-V valves close • Ventricular systole • Dupp: Pulmonary & aortic valves close • Ventricular diastole
Conduction How does the heart know when to beat? • Specialized cells keep steady heart rate • Sino-Atrial Node • This happens independent of body • http://www.youtube.com/watch?v=NEuSCPifKhA
Conduction How does the heart know when and how to beat? • Signal modified subconsciously in your Medulla Oblongata • Signal is sent to S-A Node
Stop & think • How does it benefit the organism to have the heart beat separated from neural input?
Conduction • Sinoatrial node (S-A node) • Initiates the cardiac cycle • Often called the pacemaker • Causes Atrial Syncytium • Both atria to contract (atrial systole)
Conduction • Junction Fibers • Atrioventricular node (A-V node) • A-V bundle (Bundle of His) • All these slow the signal to allow atria to completely contract
Conduction • Bundle branches • Carry impulse to ventricles on either side • Purkinje Fibers • Spread the impulse throughout the ventricular walls
Conduction • Ventricular Syncytium • Contraction of the ventricular walls (ventricular systole) • http://www.youtube.com/watch?v=bxKBQqe_Bo0
Stop & think • Why is it beneficial to have the A-V Node and Bundle Branches? What function do they serve?
http://www.youtube.com/watch?v=v3b-YhZmQu8 • http://www.youtube.com/watch?v=Ga8x1-XdXiQ