1. The Cardiovascular System
Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
The Cardiovascular System
Slides 11.1 – 11.19
Lecture Slides in PowerPoint by Jerry L. Cook
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

2. The Heart: Conduction System
Two Types of controlling systems act on the heart.
1. Nervous System: brakes & accelerates
2. Intrinsic conduction system (nodal system)
Heart muscle cells contract, without nerve impulses, in a regular, continuous way
Slide 11.13a
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3. The Heart: Conduction System
Special tissue of the intrinsic conduction system sets the pace in this order.
1. Sinoatrial node(SA Node)
Pacemaker
2. Atrioventricular node (AV Node)
3. Atrioventricular bundle
Bundle branches
4. Purkinje fibers
Slide 11.13b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

4. Heart Contractions Figure 11.5 Slide 11.14b
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5. ECG(EKG): Maps Electrical Activity & detects myocardial infarct(dead heart tissue)
P-Wave: Atrial depolarization (contraction)
QRS Wave: Ventricular Depolarization(contraction)
Atrial repolarization (relaxation) is also occurring but does not appear due to strength of vetricle contraction
T-Wave: Ventricular Repolarization (relaxation)

6. The Heart: Cardiac Cycle
Atria contract simultaneously
Atria relax, then ventricles contract
Diastole = relaxation of ventricles
Systole = contraction of ventricles
BP(blood pressure) = Systolic over Diastolic
Slide 11.16
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7. Filling of Heart Chambers – the Cardiac Cycle
Heart Sounds are valves closing
Figure 11.6
Slide 11.15
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8. The Heart: Cardiac Cycle
Cardiac cycle – events of one complete heart beat
1. Mid-to-late diastole – blood flows into ventricles
2. Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood
3. Early diastole – atria finish re-filling, ventricular pressure is low
Slide 11.17
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9. The Heart: Cardiac Output
Cardiac output (CO)
Amount of blood pumped by each side of the heart in one minute
CO = (heart rate [HR]) x (stroke volume [SV])
Stroke volume
Volume of blood pumped by each ventricle in one contraction
Slide 11.18
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10. Cardiac Output Regulation
Figure 11.7
Slide 11.19
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11. The Heart: Regulation of Heart Rate
Stroke volume usually remains relatively constant
Starling’s law of the heart – the more that the cardiac muscle is stretched, the stronger the contraction
Changing heart rate is the most common way to change cardiac output
Slide 11.20
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12. The Heart: Regulation of Heart Rate
Increased heart rate
Sympathetic nervous system
Crisis
Low blood pressure
Hormones
Epinephrine
Thyroxine
Exercise
Decreased blood volume
Slide 11.21
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

13. The Heart: Regulation of Heart Rate
Decreased heart rate
Parasympathetic nervous system
High blood pressure or blood volume
Dereased venous return
Slide 11.22
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings