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Chapter 20, part 2. The Heart. Heart chambers and valves. Structural Differences in heart chambers The left side of the heart is more muscular than the right side Functions of valves AV valves prevent backflow of blood from the ventricles to the atria
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Chapter 20, part 2 The Heart
Heart chambers and valves • Structural Differences in heart chambers • The left side of the heart is more muscular than the right side • Functions of valves • AV valves prevent backflow of blood from the ventricles to the atria • Semilunar valves prevent backflow into the ventricles from the pulmonary trunk and aorta
Figure 20.7 Structural Differences between the Left and Right Ventricles Figure 20.7a-c
Figure 20.8 Valves of the Heart Figure 20.8a
Figure 20.8 Valves of the Heart Figure 20.8b
Connective Tissues • Connective tissue fibers of the heart • Provide physical support and elasticity • Distribute the force of contraction • Prevent overexpansion • The fibrous skeleton • Stabilizes the heart valves • Physically isolates atrial from ventricular cells
Blood Supply to the Heart • Arteries include the right and left coronary arteries, marginal arteries, anterior and posterior interventricular arteries, and the circumflex artery • Veins include the great cardiac vein, anterior and posterior cardiac veins, the middle cardiac vein, and the small cardiac vein
Figure 20.9 Coronary Circulation Figure 20.9a, b
Figure 20.9 Coronary Circulation Figure 20.9c, d
Cardiac Physiology • Two classes of cardiac muscle cells • Specialized muscle cells of the conducting system • Contractile cells
Figure 20.11 An Overview of Cardiac Physiology Figure 20.11
The Conducting System • The conducting system includes: • Sinoatrial (SA) node • Atrioventricular (AV) node • Conducting cells • Atrial conducting cells are found in internodal pathways • Ventricular conducting cells consist of the AV bundle, bundle branches, and Purkinje fibers PLAY Animation: Heart flythrough
Figure 20.12 The Conducting System of the Heart Figure 20.12
Impulse Conduction through the heart • SA node begins the action potential • Stimulus spreads to the AV node • Impulse is delayed at AV node • Impulse then travels through ventricular conducting cells • Then distributed by Purkinje fibers
Figure 20.13 Impulse Conduction through the Heart PLAY Animation: Cardiac Activity Figure 20.13
The electrocardiogram (ECG) • A recording of the electrical events occurring during the cardiac cycle • The P wave accompanies the depolarization of the ventricles • The QRS complex appears as the ventricles depolarize • The T wave indicates ventricular repolarization
Figure 20.14 An Electrocardiogram Figure 20.14a
Figure 20.14 An Electrocardiogram Figure 20.14b