Download Heart Rate notes

It Keeps On Beating
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:
1. SA Node (sinoatrial node)
1.
2.
3.
4.
5.
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?
2. AV Node (atrioventricular node)
1. Located in wall between right atrium and right
ventricle
2. Delays spreading the electrical impulses for 0.1
seconds to ensure the atria are completely empty
3. 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
Click the link above to see how electrical
activity stimulates the heart to beat