1. The Anatomy of the Heart

2. Heart Wall Epicardium Outside layer AKA visceral pericardium
Three layers
Epicardium
Outside layer
AKA visceral pericardium

3. Pericardium Visceral pericardium or epicardium Next to heart
Actually part of heart wall
Parietal pericardium
Outside layer
Anchors heart to surrounding structure
Serous fluid fills the space between the layers of pericardium; eliminates friction

4. Heart Wall Middle layer Mostly cardiac muscle Layer that contracts
Myocardium
Middle layer
Mostly cardiac muscle
Layer that contracts

5. Heart Wall
Endocardium
Inner layer
Thin sheet of endothelium (simple squamous membrane)

6. Cardiac Muscle Atrial cells: 60 beats/min
Cardiac muscle can contract spontaneously and independently, even if all nervous connections are severed
Different muscle cells in different areas have different rhythms
Atrial cells: 60 beats/min
Ventricular cells: beats/min
Because of this, we need a controlling system to regulate & coordinate contractions!

7. What controls the heart beating?
2 controlling systems
Nerves of Autonomic Nervous System
Acts like “brakes” and “accelerators”
Intrinsic Conduction System
AKA nodal system
Enforces a contraction rate to keep everything together

8. Parts of Intrinsic Conduction System
Sinoatrial Node (SA node) - the pacemaker; where the action potential originates, starting each heartbeat
As action potential moves, contraction of atria is stimulated
Atrioventricular Node (AV node) - receives action potential from SA node and sends along to…

9. Parts of Intrinsic Conduction System
Atrioventricular Bundle (Bundle of His) – branches off into right and left bundle branches, and then sends action potential along to…
Purkinje Fibers – action potential received begins ventricular contraction at apex and continues contraction back up toward atria, helping to eject blood into pulmonary trunk or aortic arch

10. http://highered. mcgraw- hill
hill.com/sites/ /student_view0/chapter22/animation__co nducting_system_of_the_heart.html

11. The Cardiac Cycle Refers to one complete heartbeat
Systole – heart contraction
Diastole – heart relaxation
Since most of pumping is done by ventricles, terms usually refer to ventricles (unless otherwise stated)
Normal length of cycle: 0.8 seconds
Translates into 75 beats/min (average)

12. The Cardiac Cycle First heart sound or “lub”
Atrioventricular valves close at beginning of ventricular systole
Second heart sound or “dub”
Aortic and pulmonary semilunar valves close at beginning of ventricular diastole

13. http://highered. mcgraw- hill
hill.com/sites/ /student_view0/chapter22/animation__th e_cardiac_cycle__quiz_1_.html

14. Electrocardiogram Electrodes placed on the surface of the body
Action potentials through myocardium during cardiac cycle produces electric currents that can be measured
artdisease/Electrocardiogra m.htm

15. Electrocardiogram Pattern P wave QRS complex T wave:
Impulse moves across atria (depolarization/contraction)
QRS complex
Spread of impulse to ventricles (depolarization/ contraction)
Atria repolarization/ relaxation
T wave:
Ventricle repolarization/ relaxation
End of electrical activity

16. Cardiac Arrhythmias
When any electrical activity of the heart is irregular

17. Types of Cardiac Arrhythmias
Heart Block
AV node damaged
Ventricles beat at their own rate (slower)
Slower heart beat can lead to ischemia: lack of blood flow to heart
Leads to fibrillation: rapid, uncoordinated movement of heart muscle (= cardiac arrest, death)
Artificial pacemakers usually implanted to correct problem

18. Types of Cardiac Arrhythmias
Tachycardia
Resting heart rate above 100 bpm
Bradycardia
Resting heart rate below 60 bpm
Heart Palpitations
Premature Atrial Contractions
Misshapen “P” Wave
Premature Ventricular Contractions
Misshapen “QRS” Complex / T Wave

20. Heart Murmurs
Heart Murmurs: unusual sounds from heart (besides normal “lub- dub”)
Often indicate valve problems
If valve does not close, “swishing” sound from blood flowing back
If valve is narrowed (stenosed), “rushing” sound

21. Heart Murmurs
Doctors will listen at different locations on your chest to see if valves are functioning properly