It Keeps On Beating Name of PowerPoint Name of Course Name of Lesson Project Lead The Way© Copyright 2005

Review! What Does the Cardiovascular System Do? Fill in the Blanks: (Use these terms) temperature, hormones, oxygen, carbon dioxide, nutrients, metabolic wastes 1. Transport _____ and ______ to all cells. 2. Remove ____ and _________ from all cells.

Cardiovascular Jobs 3. Circulate _______ for chemical regulation. 4. Help maintain body __________.

Cardiac Cycle One complete sequence of pumping and filling Contraction phase is called systole Relaxation phase is called diastole Average adult at rest completes 75 cardiac cycles per minute or 0.8 seconds per cycle

What Makes the Heart Beat? Caused by electrical impulses: SA Node (sinoatrial node) Pacemaker Sets timing and rhythm of heart beat Sends electrical impulse similar to nerve impulse Triggers cells of both atria to contract in unison Impulse travels thorough cardiac cells to AV node (atrioventricular node)

What Makes the Heart Beat? AV Node (atrioventricular node) Located in wall between right atrium and right ventricle Delays spreading the electrical impulses for 0.1 seconds to ensure the atria are completely empty Sends impulses to specialized muscle fibers and Purkinje fibers, which conduct signal to apex of heart and induce ventricular contraction

What Makes the Heart Beat? Electrical Activity