1. The Cardiovascular System
Chapter 18
The Heart

2. THE HEART

4. The HEART Cardiac muscle tissue Highly interconnected cells
FOUR chambers
Right atrium
Right ventricle
Left atrium
Left ventricle

5. INTERNAL
1. SA node 2. AV node 3. AV bundle (Bundle of His) 4. Bundle branches 5. Purkinje fibers 6. Pulmonary valve 7. Aortic valve 8. Mitral (bicuspid) valve 9. Tricuspid valve
RIGHT side
LEFT side

6. EXTERNAL Right atrium Left atrium Right ventricle Left ventricle
Superior vena cava
Inferior vena cava
Aorta
Pulmonary trunk
Left pulmonary artery
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Coronary circulation
Apex
Ligamentum arteriosum
8. Mitral (bicuspid) valve
9. Tricuspid valve

7. pulmonary

9. Function of the Heart Valves

10. Blood Flow Through Heart

11. Circuits Pulmonary Circulation Systemic Circulation
The blood pathway between the right side of the heart, to the lungs, and back to the left side of the heart.
Systemic Circulation
The pathway between the heart and the rest of the body

12. Coronary Circulation From RIGHT side of heart To outer muscle of heart
Back to LEFT side of heart

13. Size, Shape, Location of the Heart
Size of a closed fist
Shape
Apex: Blunt rounded point of cone
Base: Flat part at opposite of end of cone
Located in thoracic cavity in mediastinum

14. Pericardium

15. Heart Wall Three layers of tissue
Epicardium: This serous membrane of smooth outer surface of heart
Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting
Endocardium: Smooth inner surface of heart chambers

16. Heart Wall

17. Systemic and Pulmonary Circulation

18. Heart Skeleton
Consists of plate of fibrous connective tissue between atria and ventricles
Fibrous rings around valves to support
Serves as electrical insulation between atria and ventricles
Provides site for muscle attachment

19. Cardiac Muscle
Elongated, branching cells containing 1-2 centrally located nuclei
Contains actin and myosin myofilaments
Intercalated disks: Specialized cell-cell contacts
Desmosomes hold cells together and gap junctions allow action potentials
Electrically, cardiac muscle behaves as single unit

20. Conducting System of Heart

21. Electrical Properties
Resting membrane potential (RMP) present
Action potentials
Rapid depolarization followed by rapid, partial early repolarization. Prolonged period of slow repolarization which is plateau phase and a rapid final repolarization phase
Voltage-gated channels

22. Action Potentials in Skeletal and Cardiac Muscle

23. SA Node Action Potential

24. Refractory Period
Absolute: Cardiac muscle cell completely insensitive to further stimulation
Relative: Cell exhibits reduced sensitivity to additional stimulation
Long refractory period prevents tetanic contractions

25. Electrocardiogram
Action potentials through myocardium during cardiac cycle produces electric currents than can be measured
Pattern
P wave
Atria depolarization
QRS complex
Ventricle depolarization
Atria repolarization
T wave:
Ventricle repolarization

26. Cardiac Arrhythmias Tachycardia: Heart rate in excess of 100bpm
Bradycardia: Heart rate less than 60 bpm
Sinus arrhythmia: Heart rate varies 5% during respiratory cycle and up to 30% during deep respiration
Premature atrial contractions: Occasional shortened intervals between one contraction and succeeding, frequently occurs in healthy people

27. Alterations in Electrocardiogram

28. Cardiac Cycle
Heart is two pumps that work together, right and left half
Repetitive contraction (systole) and relaxation (diastole) of heart chambers
Blood moves through circulatory system from areas of higher to lower pressure.
Contraction of heart produces the pressure

29. Cardiac Cycle

30. Events during Cardiac Cycle

31. Heart Sounds First heart sound or “lubb” Second heart sound or “dupp”
Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of ventricular systole
Second heart sound or “dupp”
Results from closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole, lasts longer
Third heart sound (occasional)
Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole

32. Location of Heart Valves

33. When Things Go Wrong: HEART
Complete handout. Then cut & paste into NB.

34. Effects of Aging on the Heart
Gradual changes in heart function, minor under resting condition, more significant during exercise
Hypertrophy of left ventricle
Maximum heart rate decreases
Increased tendency for valves to function abnormally and arrhythmias to occur
Increased oxygen consumption required to pump same amount of blood