The Heart

1
The Heart
2
Description of the Heart (Part 1)

• Heart location
• Ventral cavity Thoracic cavity Mediastinal
  cavity Pericardial cavity
• 2/3 shifted left
• Extends from rib 2 to 5th intercostal space
• Apex
• Left ventricle
• Points toward left hip
• Base
• Upper posterior surface
• Predominantly left atrium
• Sternocostal surface
• Diaphragmatic surface
• Individuals heart is about the size of the
  persons closed fist

3
Description of the Heart (Part 2)

• Pericardial Sac
• Fibrous pericardium
• Serous pericardium
• Parietal
• Visceral
• Pericardial cavity
• Cardiac Wall
• Epicardium Visceral pericardium
• Myocardium Muscle layer
• Endocardium Lining
• Chambers
• Valves

• Clinical Applications
• CPR
• Cardiac tamponade
• Pericarditis
• Myocarditis
• Endocarditis

4
Gross Anatomy of the Heart (Anterior Aspect)
5
Gross Anatomy of the Heart (Posterior Surface
View)
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Description of the Heart (Part 3)

• Cardiac Chambers
• Atria
• Thin walls
• Pectinate muscle
• Separated by
• Interatrial septum
• Fossa (foramen) ovalis
• Right
• Receives oxygen depleted blood from body
• Lowest blood pressure in body

• Left
• Receives oxygen enriched blood from lungs
• Ventricles
• Thick walls
• Trabeculae carnae
• Separated by Interventricular septum
• Right
• Receives blood from R. Atrium

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Description of the Heart (Part 4)

• Pumps blood to lungs
• Left
• Receives blood from L. atrium
• Pumps blood to body
• Highest blood pressure
• Cardiac Valves
• Structure
• Cusp
• Endocardium
• Dense connective tissue
• Chordae tendinae
• Papillary muscle

• Function
• Prevent reverse flow
• Location surface projection
• Tricuspid
• R. atrioventricular valve
• R./L. 5th intercostal space, near sternum
• Pulmonary semilunar
• R. ventricle ? pulmonary trunk
• L., 2nd intercostal space near sternum

8
Gross Anatomy of the Heart (Frontal Section)
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Description of the Heart (Part 5)

• Bicuspid (mitral)
• L. atrioventricular
• L., 5th intercostal space in midclavicular line
• Aortic semilunar
• L. ventricle ? aorta
• R., 2nd intercostal space, near sternum
• Great vessels of the Heart

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Description of the Heart (Part 6)

• Inferior vena cava (IVC)
• Coronary sinus
• Superior vena cava (SVC)
• Pulmonary trunk Right ventricle
• Pulmonary veins Left atrium
• Aorta Left ventricle

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Cardiac Conduction System (Part 1)

• Specialized myocardial cells
• Autorhythmic
• Pacemaker
• Conduction system
• Pacemaker cells set up basic rhythm of
  contractions
• Conduction system coordinates contraction of
  myocardial fibers

• Conduction system components
• Sinoatrial (SA) node
• In R. atrium near SVC opening
• Primary pacemaker
• Impulse transmits to AV node
• Maintains rhythm of 60-100 bpm
• Atrioentricular (AV) node
• In interatrial septum
• Secondary pacemaker
• Impulse transmits to AV bundle

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The Intrinsic Conduction of the Heart and
Succession of Action Potential Through Selected
Areas
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Cardiac Conduction System (Part 2)

• Sets basic rhythm if SA node is not functioning
• Maintains rhythm of 40-50
• Atrioventricular bundle (Bundle of His)
• Electrically links atria to ventricles
• In septa
• Impulse transmits to bundle branches
• Maintains rhythm of 20-40

• R.L. bundle branches
• In interventricular septum
• Impulses transmit to myoconduction fibers
• Conduction myofibers (Pukinje fibers)
• In ventricular walls
• Impulses transmit to ventricular walls
• Clinical applications
• Artificial pacemakers
• Bundle branch block
• Complete
• Right
• Left

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The Sequence of Excitation of the Heart Related
to the Deflection Waves of an ECG Tracing
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An Electrocardiogram (ECG) Tracing
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Summary of Events Occurring in the Heart During
the Cardiac Cycle
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Cardiac Cycle (Part 1)

• Events associated with one heart beat Lasts
  about 0.8 sec
• R. L. sides
• Acts simultaneously
• Develop different pressures
• Expel the same volume
• Chambers fill passively
• Atria contract while ventricles relax
• Ventricles contract while atria relax

• Systole Contraction phase
• Asystole Relaxation phase
• Phases
• Relaxation (Quiescent) period
• At end of heart beat lasts about 0.4 sec
• All 4 chambers relaxed Pressure drops backflow
  of blood
• Trapped by closing of semilunar cusps of vavles
  Dicrotic notch

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Cardiac Cycle (Part 2)

• All 4 valves closed Isovolumetric relaxation
• Ventricular pressure lt atrial pressure AV
  valves open
• Ventricular filling
• Rapid ventricular filling Passive
• Diastasis
• Atrial systole Final 30mL 0.1 sec
• End diastolic volume (EDV) about 130 mL

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Cardiac Cycle (Part 3)

• Ventricular systole
• AV valves shut 1st heart sound
• All 4 valves closed Isovolumetric contraction
• Ventricular pressure rises
• Semilunar valves open
• Ventricular ejection 0.5 sec
• Semilunar valves close 2nd heart sound
• Systole begins
• End systolic volume (ESV) 60 mL
• Stroke volume EDV ESV
• Cardiac output stroke volume x heart rate

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Factors Involved in Regulation of Cardiac Output
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Generalizing Structure of Arteries, Veins, and
Capillaries