© 2014 pearson education, inc. the human heart. © 2014 pearson education, inc. the heart the heart...
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© 2014 Pearson Education, Inc.
The Human Heart
© 2014 Pearson Education, Inc.
The Heart
• The heart is a muscular double pump
• Two functions
1. Pulmonary circuit: Right side receives oxygen-poor blood from the body and
pumps it to the lungs
2. Systemic circuit: Left side receives oxygenated blood from lungs and pumps throughout
the body
© 2014 Pearson Education, Inc.
The Heart
• Atria
• Receive blood from the pulmonary and systemic circuits
• Ventricles
• The pumping chambers of the heart
© 2014 Pearson Education, Inc.
Figure 19.1 The heart as a double pump.
Capillary bedsof lungs wheregas exchangeoccurs
Aorta andbranches
Pulmonaryarteries
Left atrium Pulmonary
veins
Right atrium
Right ventricle
Left ventricle
Venaecavae
Capillarybeds of allbody tissueswhere gasexchangeoccurs
Heart
Pulmonary Circuit
Systemic Circuit
Oxygen-rich,CO2-poor blood
Oxygen-poor,CO2-rich blood
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Figure 19.2 Location of the heart in the thorax.
Midsternal line
Rib 2
Diaphragm
Mediastinum
Heart
Right lung
T8
Posterior
Diaphragm
Apex ofheart
Pericardium(cut)
Left lung
Pulmonarytrunk
Parietalpleura (cut)
Aorta
Superiorvena cava
Mediastinum
Aorta
Left lung
Fat inepicardium
Rib 5
Pericardium(cut)
Apex of heart
Rightventricle
Right auricleof right atrium
Superiorvena cava
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Structure of the Heart—Coverings
• Pericardium—two primary layers
• Fibrous pericardium
• Strong layer of dense connective tissue
• Serous pericardium
• Formed from two layers
• Parietal layer of the serous pericardium
• Visceral layer of the serous pericardium
© 2014 Pearson Education, Inc.
Figure 19.3 The layers of the pericardium and of the heart wall.
Pericardium
Myocardium
Pulmonarytrunk
Heart chamber
Endocardium
Myocardium
Heartwall
Epicardium (viscerallayer of serouspericardium)
Pericardial cavity
Parietal layer of serouspericardium
Fibrous pericardium
© 2014 Pearson Education, Inc.
Layers of the Heart Wall
• Epicardium
• Visceral layer of the serous pericardium
• Myocardium
• Consists of cardiac muscle
• Muscle arranged in circular and spiral patterns
• Endocardium
• Endothelium resting on a layer of connective tissue
• Lines the internal walls of the heart
© 2014 Pearson Education, Inc.
Heart Chambers
• Right and left atria
• Superior chambers
• Right and left ventricles
• Inferior chambers
• Internal divisions
• Interventricular septa
• Interatrial septa
© 2014 Pearson Education, Inc.
Figure 19.5b Gross anatomy of the heart.
Anterior view
Right atrium
Right ventricle
Left ventricle
Auricle ofleft atrium
Brachiocephalic trunk
Superior vena cava
Right pulmonary artery
Ascending aorta
Pulmonary trunk
Right pulmonary veins
Right coronary artery(in coronary sulcus)
Anterior cardiac vein
Right marginal artery
Small cardiac vein
Inferior vena cava
Apex
Anterior interventricularartery (in anteriorinterventricular sulcus)
Great cardiac vein
Left coronary artery(in coronary sulcus)
Circumflex artery
Left pulmonary veins
Left pulmonary artery
Ligamentum arteriosum
Aortic arch
Left subclavian artery
Left common carotid artery
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Path of Blood Flow Through Heart
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Right Atrium
• Forms right border of heart
• Receives oxygen-poor blood from systemic circuit through these vessels:
• Superior vena cava
• Inferior vena cava
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Right Ventricle
• Receives blood from right atrium through the right atrioventricular valve (tricuspid valve)
• Pumps blood into pulmonary circuit the pulmonary trunk
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Right Ventricle
• Internal walls of right ventricle
• Trabeculae carneae
• Papillary muscles
• Chordae tendineae
• Pulmonary semilunar valve (pulmonary valve)
• Located at opening of right ventricle and pulmonary trunk
Papillary muscle
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Left Atrium
• Makes up heart’s posterior surface
• Receives oxygen-rich blood from lungs through pulmonary veins
• Opens into the left ventricle through
• Left atrioventricular valve (bicuspid valve)
• Mitral valve is another name for the left AV valve
• Bicuspid valve is another name for this.
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Left Ventricle
• Forms apex (lower tip) of the heart
• Internal walls of left ventricle
• Trabeculae carneae
• Papillary muscles
• Chordae tendineae
• Pumps blood through systemic circuit via
• Aortic semilunar valve (aortic valve)
© 2014 Pearson Education, Inc.
Figure 19.5e Gross anatomy of the heart.
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right pulmonary veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Right atrium
Right ventricle
Frontal section
Left ventricle
Left atrium
Endocardium
Myocardium
Epicardium
Interventricular septum
Papillary muscle
Pulmonary valve
Aortic valve
Mitral (bicuspid) valve
Left pulmonary veins
Left pulmonary artery
Aorta
© 2014 Pearson Education, Inc.
Left atrium
Right atrium
Aorta
Left pulmonary artery
Left pulmonary veins
Auricle of left atrium
Great cardiac vein
Posterior vein ofleft ventricle
Superior vena cava
Right pulmonary artery
Right pulmonary veins
Inferior vena cava
Coronary sinus
Right coronary artery(in coronary sulcus)
Posterior interventricularartery (in posteriorinterventricular sulcus)
Middle cardiac vein
Apex
Left ventricle
Right ventricle
Inferior view; surface shown rests on the diaphragm.
Posterior View
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Heart Valves—Valve Structure
• Each valve composed of
• Endocardium with connective tissue core
• Atrioventricular (AV) valves
• Between atria and ventricles
• Right AV valve tricuspid valve
• Left AV valve bicuspid (mitral) valve
• Aortic and pulmonary valves
• At junction of ventricles and great arteries
© 2014 Pearson Education, Inc.
Figure 19.7a Function of the atrioventricular valves. (1 of 2)
Ventricle
Direction ofblood flow
Atrium
Cusp ofatrioventricularvalve (open)
Chordaetendineae
Papillarymuscle
AV valves open; atrial pressure greater than ventricular pressure
Blood returning to theheart fills atria, pressingagainst the AV valves. Theincreased pressure forcesAV valves open.
As ventricles fill, AV valveflaps hang limply into ventricles.
Atria contract, forcingadditional blood into ventricles.
1
2
3
© 2014 Pearson Education, Inc.
Figure 19.7b Function of the atrioventricular valves. (1 of 2)
Atrium
Cusps ofatrioventricularvalve (closed)
Blood inventricle
AV valves closed; atrial pressure less than ventricular pressure
Ventricles contract, forcingblood against AV valve cusps.
Papillary musclescontract and chordaetendineae tighten,preventing valve flaps fromeverting into atria.
AV valves close.
1
2
3
© 2014 Pearson Education, Inc.
Figure 19.8 Function of the semilunar valves.
Aorta
Pulmonary trunk
Semilunar valves open
Semilunar valves closed
As ventriclescontract andintraventricularpressure rises,blood is pushedup againstsemilunar valves,forcing them open.
As ventricles relaxand intraventricularpressure falls,blood flows backfrom arteries,filling the cuspsof semilunarvalves and forcingthem to close.
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Heart Sounds
• “Lub-dup”—sound of valves closing
• First sound: “lub”
• The AV valves closing
• Second sound: “dup”
• The semilunar valves closing
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Figure 19.10 The heart is a double pump, each side supplying its own circuit.
© 2014 Pearson Education, Inc.
Heartbeat
• 70–80 beats per minute at rest
• Systole—contraction of a heart chamber
• Diastole—expansion of a heart chamber
• Systole and diastole also refer to
• Stage of heartbeat when ventricles contract and expand
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Structure of Heart Wall
• Walls differ in thickness
• Atria—thin walls
• Ventricles—thick walls
• Systemic circuit
• Longer than pulmonary circuit
• Offers greater resistance to blood flow
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Structure of Heart Wall• Left ventricle
• Three times thicker than right ventricle
• Exerts more pumping force
Rightventricle
Leftventricle
Interventricularseptum
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Cardiac Muscle Tissue
• Not all cardiac cells are innervated
• Will contract in rhythmic manner without innervation
• Inherent rhythmicity- autorhythmic
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Conducting System- The heart is AUTORHYTHMIC!! • Cardiac muscle tissue has intrinsic ability to
• Generate and conduct impulses
• Conducting system
• A series of specialized cardiac muscle cells
1. Sinoatrial (SA) node sets the inherent rate of contraction INTERNODAL PATHWAY
2. Atrioventricular (AV) node
AV bundle bundle branches Purkinje Fibers
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Figure 19.14 The intrinsic conducting system of the heart. (1 of 2)Superior vena cava Right atrium
Left atrium
Subendocardialconductingnetwork (Purkinje fibers)
Inter-ventricularseptum
Internodal pathway
1
2
3
4
5
The sinoatrial (SA)node (pacemaker)generates impulses.
The impulsespause (0.1 sec) at theatrioventricular(AV) node.
The atrioventricular(AV) bundle connects the atriato the ventricles.
The bundle branches conduct the impulsesthrough theinterventricular septum.
The subendocardialconducting network stimulates the contractilecells of both ventricles.
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Innervation
• Heart rate is set by SA node but altered by 2 extrinsic mechanisms….
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Innervation
• Parasympathetic fibers (Cardioinhibitory center in medulla of brain)
• Branches of vagus nerve
• Decrease heart rate
• Restricted to
• SA node, AV node, coronary arteries
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Innervation
• Sympathetic nerves (Cardioacceleratory center in medulla of brain)
• Travel to heart from cervical and upper thoracic chain ganglia
• Innervate SA node, AV node, coronary arteries—as parasympathetic
• Also innervate cardiac musculature throughout the heart
• Increase heart rate and strength of contraction
© 2014 Pearson Education, Inc.
Figure 19.15 Autonomic innervation of the heart.Dorsal motor nucleusof vagus
Cardioinhibitorycenter
Medulla oblongataCardioacceleratorycenter
Sympathetictrunkganglion
Thoracic spinal cord
Sympathetic trunk
The vagus nerve(parasympathetic)decreases heart rate.
Sympathetic cardiacnerves increase heart rateand force of contraction.
SAnode
AVnode
Parasympathetic fibers
Sympathetic fibers
Interneurons
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Circulation to the heart…not by the heart. How does the heart itself get
nutrients and oxygen?
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Blood Supply to the Heart
• Coronary arteries
• Blood supply to the muscular walls and tissues of the heart
• Right coronary artery
• Left coronary artery
• Arise from base of the aorta and run in the coronary sulcus
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Blood Supply to the Heart
• Left coronary artery (LCA)
• Branches into anterior interventricular artery and circumflex artery
• Left anterior descending artery (LAD) is the clinical name for anterior interventricular artery
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Blood Supply to the Heart • Right coronary artery (RCA) descends in
coronary sulcus
• Branches to form the marginal artery
• Later braches into the posterior interventricular artery. Clinically called posterior descending artery (PDA)
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Cardiac Veins
• Carry deoxygenated blood from the heart wall to the right atrium
• Coronary sinus—runs in the posterior part of the coronary sulcus
• Returns majority of venous blood from the heart to the right atrium
• Three tributaries of coronary sinus
• Great cardiac vein, middle cardiac vein, small cardiac vein
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Figure 19.16 Coronary circulation.
Superiorvena cava
The major cardiac veins
The major coronary arteries
Small cardiac vein Middle cardiac vein
Great cardiac vein
Coronary sinus
Anteriorcardiacveins
Right ventricle
Right atrium
Anastomosis(junction ofvessels)
Superiorvena cava
Aorta
Pulmonary trunk
Left atrium
Left ventricle
Rightmarginalartery
Rightcoronaryartery
Posterior interventricular artery
Anterior interventricular artery
Left coronaryartery
Circumflex artery
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Disorders of the Heart
• Coronary artery disease
• Atherosclerosis—fatty deposits
• Angina pectoris—chest pain
• Myocardial infarction—blocked coronary artery
• Heart attack
• Silent ischemia—no pain or warning
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Disorders of the Heart
• Heart failure
• Progressive weakening of the heart
• Cannot meet the body’s demands for oxygenated blood
• Congestive heart failure (CHF)
• Heart enlarges
• Pumping efficiency declines
• Pulmonary arterial hypertension
• Enlargement and potential failure of right ventricle
© 2014 Pearson Education, Inc.
Disorders of the Conduction System
• Arrythmias—variation from normal heart rhythm
• Ventricular fibrillation
• Rapid, random firing of electrical impulses in the ventricles
• Results from crippled conducting system
• Common cause of cardiac arrest
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Disorders of the Conductory System
• Arrythmias (continued)
• Atrial fibrillation
• Impulses circle within atrial myocardium, stimulating AV node
• Promotes formation of clots
• Leads to strokes
• Occurs in episodes characterized by
• Anxiety, fatigue, shortness of breath, palpitations
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