Medic 14 A&P Chapter 12

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Medic 14 A&P Chapter 12
2013-03-31 16:07:47
Medic 14

the heart
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  1. Objective:
    Describe the location and general features of the heart. (pp.437)
  2. Blood flows through a network of _____ ______ that extend between the heart and peripheral tissues
    Blood vessels
  3. Two divisions of blood vessels circuits
    • Pulmonary Circuit 
    • Systemic Circuit
  4. Pulmonary Circut
    carries blood to/from the exchange surfaces of lungs
  5. Systemic Circuit
    transports blood to/from the rest of the body
  6. Blood travels through the circuits in
    sequence, meaning blood returning to the heart from the systemic system must complete the pulmonary circuit before re-entering the systemic circuit
  7. Arteries
    Efferent vessels, carry blood away from the heart
  8. Veins
    Afferent vessels, return blood to the heart
  9. Capillaries
    • are small, thin walled vessels between the smallest arteries and the smallest veins
    • Thin walls permit exchange of nutrients,dissolved gases and waste products.
  10. Heart is the size of a
    Clenched fist
  11. The heart contains two chambers associated with each circuit
    Atrium/Ventricle for each
  12. Right Atrium
    receives blood from the systemic circuit
  13. Left Atrium
    collects blood from the pulmonary circuit
  14. Right Ventricle
    dischages blood into the pulmonary circuit
  15. Left Ventricle
    Ejects blood into the systemic circuit
  16. When the heart beats, what is the order of contraction
    Atria then ventricles
  17. Objective: Identify the layers of the hearts wall.(pp. 438-441)
  18. The heart lies anterior wall: Deep to the
  19. The connective tissue mass that divides the thoracic cavity into the pericardial cavity/ two plural cavities and contains the thymus,esophagus , and trachea is?
    The mediastinum
  20. The heart is surrounded by the _________ cavity
    Pericardial caivty
  21. The lining of the pericaridal cavity is
    the serious membrane called the pericardium
  22. Pericardium subdivisions
    • Visceral(epicardium)
    • Pericardial cavity
    • Pericardial Sac
    • Parietal
  23. Visceral Pericarium
    • Epicardium
    • covers the surface of the heart
  24. Pericardial cavity
    • normally contains a small quantity of pericardial fluid secreated by the pericardial membranes
    • acts as lubiricant and reduces friction between opposing surfaces as the heart beats
  25. Pericardial sac
    dense network of collagen fibers taht stabilizes the positions of the pericardium,heart and associated vessels in the mediastinum
  26. Atria are relatively thin muscular walls that are highly
  27. When the atrium is not filled with blood, its outer portion deflates into a lumpy wrinkled flap called
    an auricle
  28. Coronary  sulcus is a deep grove with substantial amounts of fat that mark the border between....
    artia and ventricles
  29. The two shallower depressions that mark the boundry between the left and right ventricles are
    Anterior/Posterior interventricular sulcus
  30. Apex of the heart is
    the inferior pointed tip
  31. Three layers of the heart wall
    • Epicardium(visceral pericardium) 
    • myocardium
    • endocardium
  32. Epicardium
    • Covers the outer surface of the heart
    • layer contains exposed epithelium and underlying layer of loose connective tissue that is attached to the myocardium
  33. myocardium
    • muscular wall of the heart
    • contains cardiac muscle tissue,blood vessels, and nerves.
  34. Cardiac muscle tissue of the myocardium forms concentric layers that wrap around...
    • around the artia and spiral into the walls of the ventricles 
    • this arrangement allows twisting contractions that increase pumping effenciency of the heart
  35. the hearts inner surface is covered by the
  36. Endocardium is what type of epithelium?
    Simple squamous, that is continuous with the endothelium of the attached blood vessels
  37. Traits of cardiac muscle cells
    • smaller then skeletal muscle cells
    • single centrally located nucleus
    • contain myofibrils 
    • contraction of individual sarcomeres 
    • almost totally dependent on aerobic metabolism
  38. Intercalated discs
    interlocking membranes of adjacent cells held together by desmosomes and linked by gap junctions.
  39. desmosomes help
    convey the froce of contraction from cell to cell and efficiency as they "pull together" during a contraction
  40. gap junction allows movement of
    ions and small molecules and enables action potential to travel rapidly from cell to cell
  41. Collagen and elastic fibers provide...
    • support for cardiac muscle fibers,blood vessels, and nerves of the myocardium
    • add strength and prevent overexpansion of the heart
    • help the heart return to normal shape after contractions.
    • forms the fibrous skeleton of the heart
  42. Objective: Trace the flow of blood through the heart, identifying the major blood vessels,chambers, and heart valves(pp. 442-446)
  43. Two artia are separted by the
    interatrial septum
  44. Two ventricles are separated by the
    inventricular septum
  45. Each atrium opens into the ventricle through an
    • AV valve
    • atrioventricular
  46. Right artium receives blood from the superior and inferior
    Vena cava
  47. cardiac veins of the heart return venous blood to the
    coronary sinus which opens into the right atrium slightly below the connection with the inferior vena cava
  48. fossa ovalis
    • small depression where an oval opeing- the foramen ovale penetrated the interatrial steptum from the 5th week of embryonic development until birth
    • allowed blood to flow free fro, right to left atrium while lungs are being developed
    • after 48 hours from birth it is sealed
    • if remains open after birth leads to cardiac hypertrophy and possible death
  49. Blood from the right atrium to right ventricle travels through three flaps of fibrous tissue called
    Cusps and are part of the right AV valve AKA tricuspid valve
  50. Each cusp is embraced by connective tissue fibers called
    chordae tendineae
  51. Chordae tendineae are connected to papillary muscles which are
    cone shaped projections on the inner surface of the entricle.
  52. Contraction of the papillary muscles tenses the
    chordae tendineae, limiting the movement of the cusps preventing backflow of blood
  53. blood leaving right ventricle flows into the
    pulmonary trunk, which starts pulmonary circuit
  54. What valve gaurds the entrance of the pulmonary trunk?
    pulmonary semi lunar valve
  55. Pulmonary trunk to left and right pulmonary arteries ,which branch repeatedly in
    the lungs before supplying cappillaries
  56. Respirtatory capillaries oxygenates then moves into the let and right
    pulmonary veins
  57. pulmonary veins to
    the left atrium
  58. left av valve or
    bicuspid cotains two pairs not three, aka Mitral valve
  59. left ventricle to the aorta through the
    Aortic semi lunar valve, then starts systemic circuit
  60. Right ventricle
    • due to the proximity of the lungs, it does not have to push very hard to propel blood through the pulmonary circuit
    • pulmonary blood vessels are  relatively short and wide
    • wall of right ventricle is relatively thin
  61. Left ventricle
    • thick walls
    • requires 6-7 times more force to propel through the systemic circuit
  62. When the left ventricle contracts two things happen
    • distance of between the base and apex decrease 
    • diameter of ventricular chamber decreases.
    • twising like
  63. Av valves prevent
    blood backflow from the ventricle into the artia
  64. Ventricle relaxed=
    Chordae tendinae lose and Av offers no resistance
  65. Ventricles contract=
    tension in the papillary muscles and chordae tendineae keeps the cusps from swininging into the artium
  66. swirling blood blood creates a soft but distinctive sound called
    heart murmur
  67. Pulmonary/ aortic semilunar valves prevent backflow from the
    pulmonary trunk and aorta into the right and left ventricles respectively.
  68. Due to arterial walls not contracting and stable position of cusps the, semi lunar valves do not require
    muscular bracing as the AV do
  69. Aortic sinuses
    prevent cusps from sticking to the wall of the aorta when the valve opens, they are sac like expansions at the base of aortic and next to each cusp of the aortic semilunar valve
  70. The left and right coronary arteries origionate at the
    aortic sinuses
  71. Fibrous skeleton
    consists of dense bands of elastic connective tissue that encrircle the bases of large blood vessels that carry blood away from the heart and each heart valve
  72. position of the heart valves and isolation of the artial muscule tissue from ventricular tissue is done by
    the fibrous skeleton
  73. What supplies blood to the muscle tissue of the heart?
    Coronary circulation
  74. Left and right coronary arteries origionate
    at the base of the aorta at the aortic sinuses
  75. RCA
    supplies blood to the right atrium and portions of both ventricles
  76. LCA
    supplies blood to the left ventricle, left atrium,and intraventricular septum
  77. Each coronary artery has two branches:

    branches for RCA
    marginal and posterior interventricular (descending) branches
  78. Each coronary artery has two branches:
    branches for LCA
    • circumflex
    • anterior (descending) branches
  79. Small tributaries that from the branches of the LCA and RCAform interconennections called
  80. Veins of the heart are called
    • the great and middle cardiac veins
    • carry blood away from coronary capillaries and drain into the coronary sinus
  81. coronary sinus is located
    posterior portion of the coronary sulcus.
  82. Coronary sinus opens into the
    right atrium near the base of the inferior vena cava
  83. Objective:Describe the differences in action potentials and twitch contractions of skeletal muscle fibers and cardiac muscle cells.(pp.450-451)
  84. Heartbeat
    Entire heat, atria/ventricles contract in coordinated manner
  85. Two types of Cardiac muscles cells
    • Contractile 
    • specialzied noncontractile muscle cells of the conducting system
  86. Contractile cells
    99% all cardiac muscle cells
  87. In Cardiac/skeletal muscle cells, Action potential leads to Ca2+ in the myofibrils and binds to triponin on thin filaments begins contraction. What is the major difference between skeletal and cardiac concerning this
    Duration of Action Potential, source of Ca2+, duration of contraction
  88. An action potential in ventricular cardiac muscle begins when
    the membrane is brought to threshold by stimulus (typically excitation of adjacent muscle cells)
  89. Action potential of cardiac cells steps 1
    • Rapid depolarization, at threshold, voltage-regulated sodium channels open 
    • Influx of Na+ ions rapidly depolarizes the sarcolemma (cell membrane)
    • Sodium channels close when the transmembrane potential reaches +30mV
  90. Action potential of cardiac cells steps 2
    • The plateau
    • as Na+  is actively pumped out ,voltate regulated Ca2+ channels open and extracellular Ca2+ ions enter the sarcoplasm.
    • Ca2+ channels remain open for relatively long period roughly balance the loss of Na+ from the cell.
    • Extracellular Ca2+ delay repolarization (positive charges maintain a transmembrane potential near 0mV(the plateau) and initiate contraction
    • increased contraction within the cell triggers release of Ca2+ from reserves in the SR,which continues contration
  91. Action potential of cardiac cells steps 3
    • Repolarization
    • As calcium channels begin to close, K+ channels open, and K+ ions rush out of the cell. This restores the resting potential.
  92. Depolarization of cardiac muscle is how many times longer then skeletal muscle?
    25-30 times
  93. In cardiac muscle the refractory period continues till
    relaxation is under way
  94. Automaticity
    • Autorhythmicity
    • Cardiac tissue contracts on its own in the absence of neural or hormonal stimulation
  95. Cardiac contractions are coordinated by the hearts
    • conducting system
    • a network of specialized cardiac muscles cells that initiates and distributes electrical impulses
  96. Conducting system is made of two types of cardiac muscles that do not contract
    • Nodal cells
    • Conducting cells
  97. Nodal cells
    responsible for establishing the rate of cardiac contration and located at the sinoatrial (SA) and atrioventricular (AV) nodes
  98. Conducting cells
    • which distribute the contractile stimulus to the general myocardium
    • AV bundle
    • bundle branches
    • Purkinje fibers
  99. Nodel cells depolarize how?
    spontaneously and generate action potentials at regular intervals
  100. Nodal cells are electrically coupled...
    • to one another, to conducting cells and normal cardiac cells
    • as a result when an AP is initiated in a nodal cell, it sweeps through conducting system, reaching all cardiac muscle tissue and causing a coordinated contraction
  101. Normal rate of contraction is established by
    the pacemaker cells
  102. SA node
    • sinoatrial node 
    • tissue mass embedded in the posterior wall of the right atrium, near the enterance of the superior vena cava
    • 70-80 depolarizes bpm
    • AP travels to AV node
  103. AV node
    • conduct cells in atrial wall
    • 40-60 spontaneously 
    • if AP from SA is not sent
    • located in the floor of the right atrium
    • AP travels to bundle of his
  104. AV bundle (bundle of his)
    • conducts along intraventricular septum then divides into the left and right bundle branches radiate across the inner surface of the left and right ventricles
    • Then purkinje fibers convey electrical impulses to the contractile cells of the ventricular myocardium.
  105. Etopic pacemaker
    rouge ventricular muscle cell or abnormal conducting cell  may begin generating AP and overiding the SA or AV
  106. P wave
    Depolarization of Atria
  107. QRS
    • Ventricular depolarization
    • Ventricles contract shortly after the peak of the R wave.
  108. T wave
    represents repolarization of ventricles
  109. Objective: Explain the events of the cardiac cycle and relate the heart sounds to the specific events of the cycle. (pp.457-458)
  110. The period between one heart beat and the start of the next is called
    A single cardiac cycle
  111. Cardiac cycle contains
    a period of contraction and of relaxation
  112. During contraction (systole)
    the chambers squeezes blood into an adjacent chamber or into an atrial trunk.
  113. Relaxation (diastole)
    when the chamber fills with blood and prepares for the next cardiac cycle.
  114. Pressure in each chamber rises and falls when?
    • rises in systole
    • falls in diastole
  115. Cardiac cycle in order
    • atrial systole-atrial diastole
    • ventricular systole-ventricular diastole
  116. Phases Cardiac cycle 1
    • Atrial systole beings
    • atrial contraction forces blood into relaxed ventricles
  117. Phases Cardiac cycle 2
    Atrial systole ends: atrial diastole begins
  118. Phases Cardiac cycle 3
    • Ventricular systole 1
    • ventricular contraction pushes the av valves close but does not create enough pressure to open semilunar valves
  119. Phases Cardiac cycle 4
    • ventricular systole 2
    • ventricular pressure rises and exceeds pressure in the arteries 
    • semilunar valves open and blood is ejected
  120. Phases Cardiac cycle 5
    • ventricular diastole early
    • as ventricles relax; ventricle pressure drops and blood flows back against cusps of semilunar valves and forces them closed
    • blood flows into relaxed artia
  121. Phases Cardiac cycle 6
    • Ventricle diastole
    • all chambers are relaxed ventricles fill passively
  122. Objective: 
    Define stroke volume and cardiac output and describe the factors that influence each. (pp.458-462)
  123. Heart dynamics
    movements and forces generated during cardiac contractions
  124. Stroke Volume (SV)
    The amount ejected by a ventricle in a single beat
  125. Cardiac output (CO)
    Ammount of blood pumped by each ventricle in one minute
  126. Cardiac output formula
  127. Factors that control cardiac output
    • blood volume reflexes
    • autonomic innervation
    • hormones
    • concentration of extracellular ions
    • temperature
  128. atrial reflex(bainbridge reflex)
    produces adjustments in heart rate as a response to increase in venous return,
  129. The ammount of blood pumped out of a ventricle each heart beat depends on venous return and
    filling time
  130. ANS response to heart rate
    response of SA node to ACh and NE
  131. ACh released by Parasympathetic motor neurons
    lowers heart rate
  132. NE
    raises heart rate
  133. Cardioaccelerory center
    activates sympathetic motor neurons
  134. Cardioinhibitatory center
    controls parasympathetic motor neurons
  135. Cardiac centers respond to changes in blood pressure  and
    • changes in the arterial concentrations of dissolved gasses O2 and Co2
    • Monitered by barorenceptors and chemoreceptors  innervated by the  NIX  glassopharyngeal and X vagus nerve