1. Warm-Up
Draw the human heart and the main blood vessels in/out of the heart.
Label the following on your diagram:
4 chambers
4 valves
All blood vessels going into/out of heart
Using a blue pencil, indicate oxygen-poor blood flow
Using a red pencil, indicate oxygen-rich blood flow

2. Heart Physiology

3. Heart Rhythm
Cardiac muscle cells can contract spontaneously and independently
Regulation of heart activity:
Autonomic nervous system
Epinephrine, thyroxine:  heart rate
Low Ca2+ levels:  heart rate
Intrinsic conduction system
Built into heart tissue & sets basic rhythm
Pacemaker = Sinoatrial (SA) Node

4. Intrinsic conduction system
Sequence of action:
Sinoatrial (SA) node – right atrium
Generates impulses  Starts each heartbeat
Atrioventricular (AV) node – between atria & ventricles
Atria contract
Bundle of His (or AV bundle)
Bundle branches – interventricular septum
Purkinje fibers – spread within ventricle walls
Ventricles contract

7. Electrocardiogram (ECG/EKG)
Records the electrical activity of the heart
Electrocardiograph: graphic record of heart activity

8. How to read an ECG P wave: atria contact
QRS complex: ventricles contract
T wave: ventricles relax

10. Video: How the heart’s electrical system works

11. YouTube Video: How to Read an ECG/EKG

12. Cardiac Cycle Cardiac cycle = events of one heartbeat
Systole: contraction of ventricles
Diastole: relaxation of ventricles
Cardiac Output Animation

13. Heart Sounds “Lub”: closing of AV valves
“Dub”: semilunar valves close at end of systole

14. Homeostatic Imbalances
Angina pectoris: heart muscle deprived of O2,crushing chest pain
Myocardial infarction (Heart Attack): prolonged angina, heart cells may die

15. Homeostatic Imbalances
Ischemia: Lack of adequate blood supply to heart
Fibrillation: uncoordinated shuddering of heart muscle, useless pump
Major cause of death from heart attacks

16. Homeostatic Imbalances
Damage to SA node  slower heart rate
Install artificial pacemaker
Damage to AV node  Heart block: ventricles beat at own rate (slower or not at all)
Tachycardia: rapid heart rate (>100 beats/min)
Bradycardia: very slow heart rate (<60 beats/min)
Heart murmur: abnormal or unusual heart sounds
Often valve problems

17. Cardiac Output
Cardiac Output (CO) = Heart Rate (HR) x Stroke Volume (SV)
Stroke volume: volume of blood pumped out by one ventricle with each best
Average adult:
CO = HR (75 beats/min) x SV (70 ml/beat)
CO = 5250 ml/min

18. Congestive Heart Failure
Progressive weakening of heart
Low heart efficiency  circulation inadequate to meet tissue needs
Caused by:
Coronary atherosclerosis – clogged coronary vessels
Persistent high blood pressure
Multiple heart attacks – scar tissue