Anatomy & Physiology Lecture Notes - Heart physiology

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1. 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

3. Cardiac muscle cells can contract spontaneously and
independently
Regulation of heart activity:
1.Autonomic nervous system
▪Epinephrine, thyroxine: ­ heart rate
▪Low Ca
2+
levels: ¯ heart rate
1.Intrinsic conduction system
▪Built into heart tissue & sets basic rhythm
▪Pacemaker = Sinoatrial (SA) NodeSinoatrial (SA) Node

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

7. Records the electrical activity of the heart
Electrocardiograph: graphic record of heart activity

8. P wave: atria contact
QRS complex: ventricles
contract
T wave: ventricles relax

12. Cardiac cycle Cardiac cycle = events of one heartbeat
SystoleSystole: contraction of ventricles
DiastoleDiastole: relaxation of ventricles
Cardiac Output Animation

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

14. Angina pectoris: heart muscle
deprived of O
2
,crushing chest
pain
Myocardial infarction (Heart
Attack): prolonged angina,
heart cells may die

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

16. 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 (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. 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