Transcript Heart Physiology - Riverside Preparatory High School



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
Cardiac muscle cells can contract spontaneously
and independently
 Regulation of heart activity:
1. Autonomic nervous system
▪ Epinephrine, thyroxine:  heart rate
▪ Low Ca2+ levels:  heart rate
2. Intrinsic conduction system
▪ Built into heart tissue & sets basic rhythm
▪ Pacemaker = Sinoatrial (SA) Node

Sequence of action:
1. Sinoatrial (SA) node – right atrium
▪ Generates impulses  Starts each heartbeat
2. Atrioventricular (AV) node – between atria &
ventricles
▪ Atria contract
3. Bundle of His (or AV bundle)
4. Bundle branches – interventricular septum
5. Purkinje fibers – spread within ventricle walls
▪ Ventricles contract


Records the electrical activity of the heart
Electrocardiograph: graphic record of heart activity
P wave: atria contract
QRS complex: ventricles
contract
 T wave: ventricles relax



Cardiac cycle = events of one heartbeat
 Systole: contraction of ventricles
 Diastole: relaxation of ventricles
 Cardiac Output Animation
“Lub”: closing of AV
valves
 “Dub”: semilunar
valves close at end of
systole

Angina pectoris: heart muscle
deprived of O2,crushing chest
pain
 Myocardial infarction (Heart
Attack): prolonged angina,
heart cells may die

Ischemia: Lack of adequate blood supply to heart
Fibrillation: uncoordinated shuddering of heart
muscle, useless pump
 Major cause of death from heart attacks







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

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
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
