Carotid artery Jugular vein Aorta Pulmonary trunk Heart Fig. 12.1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Carotid artery Jugular vein Aorta Pulmonary trunk Heart Brachial artery Inferior vena cava Femoral artery and vein

CO2 O2 Tissue capillaries Circulation to tissues of head Lung CO2 Fig. 12.2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. CO2 O2 Tissue capillaries Circulation to tissues of head Lung CO2 Pulmonary circulation (to lungs) Lung capillaries O2 Systemic circulation (to body) Left side of heart Right side of heart Circulation to tissues of lower body Tissue capillaries CO2 O2

Fig. 12.3 Larynx Trachea Rib Superior vena cava Aortic arch Right lung Copyright © McGraw-Hill Education. Permission required for reproduction or display. Larynx Trachea Rib Superior vena cava Aortic arch Right lung Pulmonary trunk Left atrium Right atrium Left lung Midclavicular line Right ventricle Left ventricle 2nd intercostal space Rib Apex of heart Visceral pleura Sternum Parietal pleura Pleural cavity Apex of heart Diaphragm 5th intercostal space Anterior view (a) (b)

Fig. 12.10 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Aortic arch Superior vena cava Left pulmonary artery Branches of left pulmonary arteries Branches of right pulmonary arteries 4 4 8 Pulmonary trunk 5 Pulmonary veins Aortic semilunar valve 5 Pulmonary veins Left atrium 3 6 Pulmonary semilunar valve 7 Bicuspid valve 1 Right atrium Left ventricle Tricuspid valve 2 Interventricular septum Right ventricle Inferior vena cava (a) 1 2 3 4 Superior and inferior vena cava Right atrium Tricuspid valve Right ventricle Pulmonary semilunar valve Pulmonary trunk Pulmonary arteries Coronary sinus Cardiac veins Body tissues (systemic circulation) Heart tissue (coronary circulation) Lung tissue (pulmonary circulation) Coronary arteries Aortic semilunar valve Left ventricle Left atrium Pulmonary veins Aorta Bicuspid valve 8 7 6 5 (b)

Right pulmonary artery Fig. 12.5b Copyright © McGraw-Hill Education. Permission required for reproduction or display. Aorta Superior vena cava Left pulmonary artery Right pulmonary artery Left pulmonary veins Right pulmonary veins Left atrium Right atrium Great cardiac vein Inferior vena cava Coronary sinus Right coronary artery Left Ventricle Small cardiac vein Posterior interventricular artery (in posterior interventricular sulcus) Middle cardiac vein (in posterior inter- Ventricular sulcus) Right ventricle Apex (c) Posterior view

Fig. 12.13 Striations Branching muscle fibers Intercalated disks Copyright © McGraw-Hill Education. Permission required for reproduction or display. Striations Branching muscle fibers Intercalated disks Nucleus of cardiac muscle cell T tubule Sarcoplasmic reticulum LM 400x (b) Sarcomere T tubule Myofilbrils Sarcoplasmic reticulum Mitochondrion Sarcolemma (cell membrane) Connective tissue (a) Sarcomere Nucleus of cardiac muscle cell Mitochondrion Myofibrils (c) b: ©Ed Reschke

Fig. 12.11 Aortic arch Aortic arch Superior vena cava Pulmonary trunk Copyright © McGraw-Hill Education. Permission required for reproduction or display. Aortic arch Aortic arch Superior vena cava Pulmonary trunk Aortic semilunar valve Superior vena cava Pulmonary trunk Left coronary artery Left atrium Left atrium Right atrium Circumflex artery Right coronary artery Posterior vein of left ventricle Left marginal artery Right atrium Into right atrium Anterior interventricular artery Coronary sinus Posterior interventricular artery Middle cardiac vein Great cardiac vein Right marginal artery Small cardiac vein Left ventricle Left ventricle Right ventricle Right ventricle (a) Anterior view (b) Anterior view

Fig. 12.14 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Skeletal Muscle Cardiac Muscle Repolarization phase Plateau 2 phase 1 (mV) (mV) 2 1 Repolarization phase 3 Depolarization phase Depolarization phase –85 –85 1 2 1 2 500 Time (ms) Time (ms) 3 Tension Tension 4 1 2 1 2 500 Time (ms) Time (ms) (a) 1 Depolarization phase (b) 1 Depolarization phase • Na+ channels open. • Na+ channels open. • K+ channels begin to open. • Ca+ channels open. 2 Repolarization phase 2 Plateau phase • Na+ channels close. • Na+ channels close. • K+ channels continue to open, causing repolarization. • Some K+ channels open, causing repolarization. • K+ channels close at the end of repolarization and return the membrane potential to its resting value. • Ca2+ channels are open, producing the plateau by slowing further repolarization. 3 Repolarization phase 3 Refractory period effect on tension • Ca2+ channels close. • Maximum tension is obtained after the refractory period (purple shaded area) is completed allowing for increased tension with additional stimulation. • Many K+ channels open. 4 Refractory period effect on tension • Cardiac muscle contracts and relaxes almost completely during the refractory period (purple shaded area).

Pulmonary semilunar valve Cardiac skeleton Aortic semilunar valve Fig. 12.9 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pulmonary semilunar valve Cardiac skeleton Aortic semilunar valve Bicuspid valve Tricuspid valve Cardiac muscle of the right ventricle Cardiac muscle of the left ventricle Posterior view

Fig. 12.15 Sinoatrial (SA) node 1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Sinoatrial (SA) node 1 Action potentials originate in the sinoatrial (SA) node and travel across the wall of the atrium (arrows) from the SA node to the atrioventricular (AV) node. Left atrium Atrioventricular (AV) node 1 2 Action potentials pass through the AV node and along the atrioventricular (AV) bundle, which extends from the AV node, through the fibrous skeleton, into the interventricular septum. 2 3 The AV bundle divides into right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches. Left ventricle 3 Atrioventricular (AV) bundle 4 Action potentials are carried by the Purkinje fibers from the bundle branches to the ventricular walls. Right and left bundle branches 4 Purkinje fibers Apex

QRS complex R (mV) T wave P wave Q S PQ interval QT interval Fig. 12.16 Copyright © McGraw-Hill Education. Permission required for reproduction or display. QRS complex R (mV) T wave P wave Q S PQ interval QT interval Time (seconds)

Aortic semilunar valve Left pulmonary veins Right pulmonary veins Fig. 12.6 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Aortic arch Superior vena cava Left pulmonary artery Pulmonary trunk Branches of right pulmonary artery Right pulmonary veins Aortic semilunar valve Left pulmonary veins Right pulmonary veins Left atrium Pulmonary semilunar valve Bicuspid (mitral) valve Right atrium Coronary sinus Left ventricle Chordae tendineae Tricuspid valve Papillary muscles Interventricular septum Right ventricle Inferior vena cava Anterior view

Fig. 12.7 Bicuspid valve Tricuspid valve Pulmonary trunk Chordae Copyright © McGraw-Hill Education. Permission required for reproduction or display. Bicuspid valve Tricuspid valve Pulmonary trunk Chordae tendineae Pulmonary semilunar valve Papillary muscles Aorta Aortic semilunar valve Left ventricle Right ventricle Tricuspid valve Bicuspid valve Right atrium Anterior view Superior view (a) (b) a: ©VideoSurgery/Science Source; b: ©Oktay Ortakcioglu/iStock/360/Getty Images RF

Fig. 12.8 Pulmonary veins Pulmonary veins Left atrium Aorta Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pulmonary veins Pulmonary veins Left atrium Aorta Left atrium Aorta Bicuspid valve (open) Bicuspid valve (closed) Aortic semilunar valve (open) Aortic semilunar valve (closed) Chordae tendineae (tension low) Chordae tendineae (tension high) Papillary muscle (relaxed) Papillary muscle (contracted) Cardiac muscle (relaxed) Cardiac muscle (contracted) Left ventricle (relaxed) Left ventricle (contracted) (a) Anterior view (b) Anterior view

Fig. 12.17 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Semilunar valves closed Semilunar valves closed AV valves opened AV valves opened 1 The atria and ventricles are relaxed. AV valves open, and blood flows into the ventricles. The ventricles fill to approximately 70% of their volume. 2 The atria contract and complete ventricular filling. Semilunar valves closed Semilunar valves closed AV valves closed AV valves closed 5 At the beginning of ventricular diastole, the ventricles relax, and the semilunar valves close (the second heart sound). 3 Contraction of the ventricles causes pressure in the ventricles to increase. Almost immediately, the AV valves close (the first heart sound). The pressure in the ventricles continues to increase. Semilunar valves opened AV valves closed 4 Continued ventricular contraction causes the pressure in the ventricles to exceed the pressure in the pulmonary trunk and aorta. As a result, the semilunar valves are forced open, and blood is ejected into the pulmonary trunk and aorta.

©Jose Luis Pelaez Inc/Blend Images LLC RF Fig. 12.19 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pulmonary semilunar valve Aortic semilunar valve Bicuspid valve Tricuspid valve Outline of heart ©Jose Luis Pelaez Inc/Blend Images LLC RF

Fig. 12.22 1 Sensory neurons (green) carry Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 Sensory neurons (green) carry action potentials from baroreceptors to the cardioregulatory center. Chemoreceptors in the medulla oblongata influence the cardioregulatory center. Cardioregulatory center and chemoreceptors in medulla oblongata Sensory nerve fibers Baroreceptors in wall of internal carotid artery 2 The cardioregulatory center controls the frequency of action potentials in the parasympathetic neurons (red ) extending to the heart. The parasympathetic neurons decrease the heart rate. 1 Carotid body chemoreceptors Sensory nerve fibers Baroreceptors in aorta 3 The cardioregulatory center controls the frequency of action potentials in the sympathetic neurons (blue) extending to the heart. The sympathetic neurons increase the heart rate and the stroke volume. 2 Parasympathetic nerve fibers 3 SA node Sympathetic nerve fibers 4 The cardioregulatory center influences the frequency of action potentials in the sympathetic neurons (blue) extending to the adrenal medulla. The sympathetic neurons increase the secretion of epinephrine and some norepinephrine into the general circulation. Epinephrine and norepinephrine increase the heart rate and stroke volume. Heart Sympathetic nerve fibers to adrenal gland 4 Circulation Adrenal medulla Epinephrine and norepinephrine

Fig. 12.20 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3 4 Actions Reactions Baroreceptors in the carotid arteries and aorta detect an increase in blood pressure. Effectors Respond: The SA node and cardiac muscle decrease activity and heart rate and stroke volume decrease. The cardioregulatory center in the brain decreases sympathetic stimulation of the heart and adrenal medulla and increases parasympathetic stimulation of the heart. 5 Homeostasis Disturbed: Blood pressure increases. Homeostasis Restored: Blood pressure decreases. 2 Blood pressure (normal range) 1 Start here Blood pressure (normal range) 6 Homeostasis Disturbed: Blood pressure decreases. Homeostasis Restored: Blood pressure increases. Actions Reactions Baroreceptors in the carotid arteries and aorta detect a decrease in blood pressure. Effectors Respond: The SA node and cardiac muscle increase activity and heart rate and stroke volume increase. The cardioregulatory center in the brain increases sympathetic stimulation of the heart and adrenal medulla and decreases parasympathetic stimulation of the heart.

Fig. 12.21 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3 4 Actions Reactions Chemoreceptors in the medulla oblongata detect an increase in blood pH (often caused by a decrease in blood CO2). Control centers in the brain decrease stimulation of the heart and adrenal medulla. Effectors Respond: The SA node and cardiac muscle decrease activity and heart rate and stroke volume decrease. 5 Homeostasis Restored: Blood pH decreases. 2 Homeostasis Disturbed: Blood pH increases. (normal range) Blood pH 1 Start here (normal range) Blood pH 6 Homeostasis Disturbed: Blood pH decreases. Homeostasis Restored: Blood pH increases. Actions Reactions Chemoreceptors in the medulla oblongata detect a decrease in blood pH (often caused by an increase in blood CO2). Control centers in the brain increase stimulation of the heart and adrenal medulla. Effectors Respond: The SA node and cardiac muscle increase activity and heart rate and stroke volume increase, increasing blood flow to the lungs.

(left): ©Hank Morgan/Science Source; (right): ©SPL/Science Source Fig. 12A Copyright © McGraw-Hill Education. Permission required for reproduction or display. Occluded coronary artery (left): ©Hank Morgan/Science Source; (right): ©SPL/Science Source

Myocardial Infarctions Page 345 Copyright © McGraw-Hill Education. Permission required for reproduction or display. MUSCULAR Skeletal muscle activity is reduced because of lack of blood flow to the brain and because blood is shunted from blood vessels that supply skeletal muscles to those that supply the heart and brain. URINARY NERVOUS Pallor of the skin results from intense vasoconstriction of peripheral blood vessels, including those in the skin. Decreased blood flow to the brain, decreased blood pressure, and pain due to ischemia of heart muscle result in increased sympathetic and parasympathetic stimulation of the heart. Loss of consciousness occurs when the blood flow to the brain decreases so that not enough O2 is available to maintain normal brain function, especially in the reticular activating system. Myocardial Infarctions URINARY Blood flow to the kidney decreases dramatically in response to sympathetic stimulation. If the kidney becomes ischemic, the kidney tubules can be damaged, resulting in acute renal failure and reduced urine production. increased blood urea nitrogen, increased blood levels of K+, and edema are indications that the kidneys cannot eliminate waste products and excess water. If damage is not too great, the period of reduced urine production may last up to 3 weeks; then the rate of urine production slowly returns to normal as the kidney tubules heal. Symptoms Chest pain that radiates down left arm ENDOCRINE Tightness and pressure in chest Difficulty breathing When blood pressure becomes low, antidiuretic hormone (ADH) is released from the posterior pituitary gland, and renin, released from the kidney, activates the renin angiotensin-aldosterone mechanism. ADH, secreted in large amounts, and angiotensin II cause vasoconstriction of peripheral blood vessels. ADH and aldosterone act on the kidneys to retain water and ions. increased blood volume increases venous return, which results in increased stroke volume and blood pressure unless damage to the heart is very severe. Nausea and vomiting Dizziness and fatigue Treatment Restore blood flow to cardiac muscle Medication to reduce blood clotting (aspirin) and increase blood flow (t-Pa) Supplemental O2 to restore normal O2 to heart tissue Prevention and control of hypertension DIGESTIVE Intense sympathetic stimulation reduces blood flow to the digestive system to very low levels, which often results in nausea and vomiting. Angioplasty or bypass surgery LYMPHATIC AND IMMUNE RESPIRATORY White blood cells, including macrophages, move to the area of cardiac muscle damage and phagocytize any dead cardiac muscle cells. Decreased blood pressure results in decreased blood flow to the lungs. the decrease in gas exchange leads to increased blood co2 levels, acidosis, and decreased blood O2 levels. Initially, respiration becomes deep and labored because of the elevated CO2 levels, decreased blood pH, and depressed O2 levels. If the blood O2 levels decrease too much, the person loses consciousness. Pulmonary edema can result when the pumping effectiveness of the left ventricle is substantially reduced..