1. The Cardiovascular System: The Heart Physiology
Chapter 18, Cardiovascular System
Chapter 18, Cardiovascular System

2. Cardiac Muscle Contraction
Heart muscle:
______________________________________________________________________
____________________________
Has a long (250 ms) absolute refractory period
Cardiac muscle contraction is similar to skeletal muscle contraction
Chapter 18, Cardiovascular System

3. Heart Physiology: Intrinsic Conduction System
Autorhythmic cells:
__________________________________
Have unstable resting potentials called ________________________
Use _________________(rather than sodium) for rising phase of the action potential
Chapter 18, Cardiovascular System

4. Pacemaker and Action Potentials of the Heart
Chapter 18, Cardiovascular System
Figure 18.13

5. Heart Physiology: Sequence of Excitation
___________________generates impulses about 75 times/minute
___________________delays the impulse approximately 0.1 second
Chapter 18, Cardiovascular System

6. Heart Physiology: Sequence of Excitation
Impulse passes from atria to ventricles via the atrioventricular bundle (____________)
AV bundle splits into two pathways in the interventricular septum (bundle branches)
__________________carry the impulse toward the apex of the heart
___________________carry the impulse to the heart apex and ventricular walls
Chapter 18, Cardiovascular System

7. Heart Physiology: Sequence of Excitation
Chapter 18, Cardiovascular System
Figure 18.14a

8. Heart Excitation Related to ECG
Chapter 18, Cardiovascular System
Figure 18.17

9. Extrinsic Innervation of the Heart
Heart is stimulated by the _______________ cardioacceleratory center
Heart is inhibited by the _______________ cardioinhibitory center
Chapter 18, Cardiovascular System
Figure 18.15

10. Chapter 18, Cardiovascular System
Electrocardiography
Electrical activity is recorded by ___________________________
_____________corresponds to depolarization of SA node
QRS complex corresponds to ventricular depolarization
______________corresponds to ventricular repolarization
Atrial repolarization record is masked by the larger QRS complex
InterActive Physiology®: Cardiovascular System: Intrinsic Conduction System
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Chapter 18, Cardiovascular System

11. Chapter 18, Cardiovascular System
Electrocardiography
Chapter 18, Cardiovascular System
Figure 18.16

12. Chapter 18, Cardiovascular System
Heart Sounds
Heart sounds (________) are associated with closing of heart valves
First sound occurs as _____________and signifies beginning of systole (contraction)
Second sound occurs when _____________at the beginning of ventricular diastole (relaxation)
Chapter 18, Cardiovascular System

13. Chapter 18, Cardiovascular System
Cardiac Cycle
Cardiac cycle refers to all events associated with blood flow through the heart
Systole – ____________ of heart muscle
Diastole – ___________of heart muscle
Chapter 18, Cardiovascular System

14. Phases of the Cardiac Cycle
_______________– mid-to-late diastole
Heart blood pressure is low as blood enters atria (passively) and flows into ventricles
________________, then atrial systole occurs
Chapter 18, Cardiovascular System

15. Phases of the Cardiac Cycle
______________(contraction)
_____________________
Rising ventricular pressure results in closing of AV valves
Isovolumetric contraction phase
_____________________phase opens semilunar valves
Chapter 18, Cardiovascular System

16. Phases of the Cardiac Cycle
Chapter 18, Cardiovascular System
Figure 18.20

17. Cardiac Output (CO) and Reserve
Cardiac Output is the amount of blood pumped by each ventricle in one minute
__________________________________________________________________________________
HR is the number of heart beats per minute
SV is the amount of blood pumped out by a ventricle with each beat
__________________is the difference between resting and maximal CO
Chapter 18, Cardiovascular System

18. Cardiac Output: Example
_____________________________________
Chapter 18, Cardiovascular System

19. Regulation of Stroke Volume
SV = __________________________________________________________________________
________ = amount of blood collected in a ventricle during diastole
________ = amount of blood remaining in a ventricle after contraction
Chapter 18, Cardiovascular System