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Exercise 35
Anatomy of the Heart
Gross anatomy of the heart
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Localized in the mediastinum
It has a pointed apex
 At the level of the 5th intercostal space
And a broad base
 Beneath the 2nd rib
 Is the site of emerging of the great vessels
The pericardium
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Pericardial cavity
Visceral pericardium or epicardium
Parietal pericardium
 Pericardial fluid
Pericardial sac (fibrous)
 Stabilizes the heart and its vessels
Pericarditis
The Location of the Heart in the
Thoracic Cavity
Figure 20.2c
Gross anatomy of the heart
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Myocardium
 Muscle wall of the heart
 Fibrous skeleton of the heart
Endocardium
Superficial Anatomy of the
Heart
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The heart consists of four chambers
 Two atria
• Two auricles
 Two ventricles
Major blood vessels of the heart include
 Inferior and superior vena cavae
 Aorta, pulmonary trunk and pulmonary veins
The Superficial Anatomy of the
Heart
The Superficial Anatomy of
the Heart
Figure 20.3b, c
The superficial Anatomy of
the heart
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Atria
 Thin walled upper chambers that receive blood
from the vena cava
Ventricles
 Thick walled lower chambers separated from the
atria by AV valves
External anatomy of the
heart and blood flow
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Right atrium (RA)
 Receives blood coming from the body via
superior, inferior vena cava and coronary sinus
 auricle
Right ventricle (RV)
 Receives blood from the RA and pumps it into
the pulmonary trunk
Pulmonary trunk
 Left and right pulmonary arteries
External anatomy of the
heart and blood flow
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Lungs
Pulmonary veins
 2 rights and 2 lefts
Left atrium (LA)
 Receives blood from the pulmonary veins
 Auricle
External anatomy of the
heart and blood flow
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Left ventricle (LV)
 Pumps blood into the aorta
Aorta
 Ascending, arch, descending
Ligamentum arteriosum
 Remnant of the ductus arteriosus
 Between pulmonary artery and aorta
Blood supply to the heart
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Coronary arteries and coronary sulcus
 Right
• Posterior interventricular artery
• Marginal
• Supplies posterior part of the ventricles and
lateral part of the right heart
Blood supply to the heart
Left coronary
• Anterior interventricular artery
• Circumflex
• Supplies the anterior part of the
ventricles and laterodorsal part of
the heart
 Anterior and posterior interventricular
sulci
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Blood Supply to the Heart veins
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Veins that empty into the coronary sinus
 Great cardiac vein (anterior interventricular) ,
Middle cardiac vein (posterior interventricular),
Small cardiac vein
Coronary Circulation
Figure 20.9a, b
The Sectional Anatomy of the
Heart
Internal anatomy of the heart
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Right atrium
 Fossa ovalis
• Foramen ovale
 Openings of the superior and inferior vena cavas
 Pectinate muscle
 SA and AV nodes
 Interatrial septum
• Wall between atria
Internal anatomy of the heart
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Right ventricle
 Tricuspid valve
 Chordae tedineae
 Papillary muscles
 Trabeculae carneae – muscular ridges
 Interventricular septum
• Wall between ventricles
Internal anatomy of the heart
Moderator band (septomarginal band)
• Horizontal muscular ridge
• Brings the impulse to the papillary muscles
• Only present in the RV
 Conus arteriosus
• Conical pouch from which the pulmonary
artery arises
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Internal anatomy of the heart
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Left atrium
 Principal cavity (sinus)
 Pectinate muscles on the auricle only
 Openings of the pulmonary veins
Internal anatomy of the heart
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Left ventricle
 Bicuspid valve
 Trabeculae carneae
 Papillary muscles
 Chordae tendineae
Valves of the Heart
Figure 20.8a
Valves of the Heart
Figure 20.8b
Valves of the heart
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Bicuspid or mitral or left AV
Tricuspid or right AV
Aortic semilunar
Pulmonary semilunar
The intrinsic conducting
system
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Functional syncytium
 Gap junctions
The intrinsic conducting
system
The intrinsic conducting
system
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Controlling system over the heart
 Autonomic nervous system
• Sympathetic
• Parasympathetic
 Intrinsic conducting system or
nodal system
• Specialized myocardial tissue
• Initiates the heart beat
The Intrinsic Conducting
System
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The conducting system includes:
 Sinoatrial (SA) node (80-100 bpm)
• Contain the pacemaker cells
• Located in the right atrium
 Atrioventricular (AV) node (40-60 bpm)
• Located in the atrium septum at the junction
of the atria and ventricles
The Intrinsic Conducting
System
AV bundle or bundle of His
• Located in the interventricular septum
 Right and Left bundle branches
• Located in the interventricular septum
 Purkinje fibers
• Located in the myocardium
• Larger in the left ventricle
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Steps for the heart beat
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SA node begins the action potential
Stimulus spreads across the atria
Stimulus spreads to the AV node
Atrial contraction
Impulse then travels through the AV bundle
Impulse reaches right and left bundle branches
Steps for the heart beat
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Then it reaches the Purkinje fibers
Impulse reaches the papillary muscles
(via moderator band on the right side)
Impulse is spread to the ventricles
Ventricular contraction
The Intrinsic Conducting
System
Pulmonary and systemic
circulation
Pulmonary circulation
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Pulmonary arteries
 Leave the RV
 Carry blood rich in CO2
 Blood flows to the lungs
Pulmonary veins
 Leave the lung
 Blood rich in O2
 Blood flows to the LA
Systemic circulation
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Aorta
 Leaves the LV
 Blood rich in O2
 Blood flows to the body
Vena cava
 Superior brings blood from head, neck, arms and
superior trunk
 Inferior brings blood from the rest of the body
 Blood rich in CO2
 Blood flows to the RA
Microscopic anatomy of the
heart
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Involuntary
Cardiac cells
 Intercalated discs
 Branching
 Central nucleus
 Striations
Identify these structure on
the fresh heart
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RA
 Auricle
 Pectinate muscles
 Superior and inferior vena cavas
 Coronary sinus
 Tricuspid valve
Identify these structure on
the fresh heart
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RV
 Papillary muscles
 Chrodae tendineae
 Trabeculi carneae
 Moderator band
 Pulmonary trunk and its semilunar valve
Identify these structure on
the fresh heart
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LA
 Auricle
 Pectinate muscles
Identify these structure on
the fresh heart
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LV
 Myocardium
 Papillary muscles
 Chordae tendineae
 Mitral valve
 Trabeculi carneae
 Interventricular septum
 Aorta and its semilunar valve
 Coronary arteries