The Cardiovascular system

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• TheCardio-vascular system

Madeline Gervase RN,MSN,CCRN,FNP
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Contents

• Cardiovascular system components
• Heart Anatomy
• Cardiac Physiology
• Conduction system
• Cardiac cycle
• Cardiac output
• Control of heart function

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Cardiovascular systemcomponents

• Heart
• Pumps blood into blood vessels
• Located in mediastinum
• Blood Vessels
• Carry blood throughout the body

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ANATOMY Heart in mediastinum
Figure 20.2a, b
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The pericardia membranes

• Fibrous pericardium Outer most, rigid, prevents
  overstretching
• Parietal pericardium (serous) Interior to
  fibrous
• Visceral pericardium or epicardium(serous)
  Wrapped around heart
• Pericardial fluid released by serous layers,
  lubricates for easy gliding

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Superficial Anatomy of the Heart

• The heart consists of four chambers
• Two atria and two ventricles separated by septum
• Major blood vessels of the heart include
• Inferior and superior vena cavae
• Aorta and pulmonary trunk
• Blood vessels supported by fat in sulcus (groove)

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The Superficial Anatomy of the Heart
Figure 20.3a
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The Superficial Anatomy of the Heart
Figure 20.3b, c
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The Heart Wall

• Components of the heart wall include
• Epicardium Outermost, Serous
• Myocardium Middle, muscle layer
• Endocardium Innermost, endothelium

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Internal Anatomy

• Chambers Atria and Ventricles
• RA, RV, LA, LV
• Septum Inter-atrial and inter-ventricular
• Valves AV and SL valves
• AV Mitral/Bicuspid Tricuspid
• SL Aortic Pulmonic
• Chordae tendineae
• Papillary muscle and trabeculae carneae

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The Sectional Anatomy of the Heart
Figure 20.6c
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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

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Valves of the Heart
Figure 20.8b
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Connective Tissues

• Connective tissue fibers of the heart
• Provide physical support and elasticity
• Distribute the force of contraction
• Prevent overexpansion

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Blood flow through Heart
Animation Diagrammatic Frontal Section through
the Heart
Figure 20.6a, b
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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

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Coronary Circulation
Figure 20.9a, b
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Cardiac Physiology and Cardiac muscle cell types

• Autorhythmic cells Specialized muscle cells
• -Self depolarizing
• -Form the conduction system and carry impulse
• Contractile cells Cells that contract in
  response to impulse

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The Conduction System

• The conduction system includes
• Sinoatrial (SA) node
• Inter nodal pathway
• Atrioventricular (AV) node
• AV Bundle/Bundle of His
• Right and Left Bundle Branches
• Purkinje fibers
• Conduction system sets sinus rhythm

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Sinus rhythm

• Rhythmic impulse generation by conduction system.
  Responsible for heart beat
• Depolarization rates of components
• SAN/Atria 60-100/min
• AVN 40 - 60/min
• Bundle Branches/Ventricle 20-40/min
• SAN sets the pace(70beats/min.) Pace maker of
  the Heart

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Normal Cardiac Complex

• P wave Atrial depolarization
• PR interval SA AV node conduction time
• .12 - .20 msec
• QRS wave Ventricular Depolarization .06-.12 msec
• T wave Ventricular Repolarization

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Impulse Conduction through the heart

• Impulse begins with the SA node
• Impulse travels through atria by inter-nodal
  pathway
• Impulse spreads to AV node
• Impulse delayed at AV node
• Impulse travels through AV bundle and branches
• Impulse distributed throughout ventricles by
  Purkinje fibers

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Abnormal rhythm

• Ectopic focus increased excitability out side
  SAN which can be caused by caffeine, nicotine.
• Heart blocks caused by blockage due to damaged
  conduction system. Can be partial or total. Most
  common blockage site is AV node
• Heart block results in incomplete contraction
  of ventricles. Sometimes a block will lead to
  self impulse generation by ventricles

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Cardiac muscle contraction

• Resting membrane potential of approximately
• 90mV
• Action potential
• Rapid depolarization
• A plateau phase unique to cardiac muscle
• Repolarization
• Refractory period follows the action potential.
  Longer refractory period enables ventricles to
  fill

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Action Potential
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Skeletal Vs. Cardiac muscle contraction

• Impulse generation Intrinsic in cardiac muscle,
  extrinsic in skeletal muscle
• Plateau phase Present in cardiac muscle, absent
  in skeletal muscle
• Refractory period long in cardiac muscle,
  shorter in skeletal muscle
• Summation Impossible in cardiac muscle, possible
  in skeletal muscleCalcium Ion and Cardiac muscle
  contraction
• Cardiac action potentials cause an increase in
  Ca2 in sarcoplasmic reticulum
• Ca2 enters the myofibril during the plateau
  phase
• This maintains the contraction which aid in heart
  function