Card Set Information

2014-05-05 04:00:42

heart exam
Show Answers:

  1. what are the receiving chambers of the heart
    • right atrium: receives blood returning from systemic circuit
    • left atrium: receives blood returning from pulmonary circuit
  2. two pumping chambers of the heart
    • right ventricle: pumps blood through pulmonary circuit
    • left ventricle: pumps blood through systemic circuit
  3. describe the location of the heart
    • mediastinum between second rib and fifth intercostal space
    • superior surface of diaphragm
    • anterior to vertebral column
    • posterior to sternum
  4. apical impulse
    palpated between fifth and sixth ribs
  5. apex of the heart points where
    toward left hip
  6. base of the heart leans towards
    right shoulder
  7. pericardium
    • double walled sac
    • superficial fibrous pericardium: protects anchors to surrounding structures, and prevents overfilling
    • deep two layered serous pericardium (parietal and visceral layer)
  8. parietal layer of serous pericardium
    lines internal surface of fibrous pericardium
  9. visceral layer of serous pericardium
    also known as the epicardium on external surface of the heart
  10. what separates the parietal and visceral layers of the serous pericardium
    pericardial cavity filled with fluid to decrease friction
  11. pericarditis
    • inflammation of pericardium
    • roughens membrane surfaces
  12. cardiac temponade
    excess fluid sometimes compresses heart, creating limited pumping ability
  13. what are the three layers of the heart wall
    • epicardium (visceral layer of serous pericardium)
    • myocardium
    • endocardium
  14. myocardium
    • spiral bundles of contractile cardiac muscle cells
    • cardiac skeleton: crisscrosing, interlacing layer of connective tissue
    • anchors cardiac muscle fibers
    • suppots great vessels and valves
    • limits spread of action potentials to specific paths
  15. endocardium
    • continuous with endothelial lining of blood vessels
    • lines heart chambers
    • covers cardiac skeleton of valves
  16. interatrial septum
    separates atria
  17. interventricular septum
    separates ventricles
  18. fossa ovalis
    remnant of foramen ovale of fetal heart
  19. coronary sulcus
    encircles junction of atria and ventricles (atrioventricular groove)
  20. anteiror interventricular sulcus
    anterior position of the interventricular septum
  21. posterior interventricular sulcus
    landmark on posteroinferior surface
  22. auricles
    appendages that increase atrial volume
  23. right atrium
    • pectinate muscles
    • posterior and anterior regions separated by crista terminalis
  24. left atrium
    pectinate muscles only in auricles
  25. atria: the receiving chambers
    • small, thin walled
    • contribute little to propulsion of blood
    • three veins empty into right atrium (superior vena cava, inferior vena cava, coronary sinus)
    • four pulmonary veins empty into left atrium
  26. ventricles: the discharging chambers
    • most of the volume of the heart
    • right ventricle: most anterior surface
    • left ventricle: posteroinferior surface
    • trabeculae carneae: irregular ridges of muscle on walls
    • papillary muscles: anchor chordae tendineae
    • thicker walls than atria
    • actual pumps of heart
    • right ventricle: pumps blood into pulmonary trunk
    • left ventricle: pumps blood into aorta
  27. whats the largest artery in the body
    the aorta
  28. heart valves
    • ensure unidirectional blood flow through heart
    • open and close in response to pressure changes
    • two atrioventricular (AV) valves and two semilunar (SL) valves
  29. atrioventricular valves
    • prevent backflow into atria when ventricles contract
    • tricuspid valve (right AV valve)
    • mitral valve (left AV valve, bicuspid valve)
    • chordae tendineae anchor cusps to papillary muscles (hold valve flaps in closed position)
  30. semilunar valves
    • prevent backflow into ventricles when ventricles relax
    • open and close in response to pressure changes
    • aortic semilunar valve
    • pulmonary semilunar valve
  31. what two conditions severely weaken the heart
    • incompetent balve: blood backflows so heart repumps same blood over and over
    • valvular stenosis: stiff flaps, constrict opening so the heart must exert more force to pump blood
  32. pulmonary circuit
    • right atrium > tricuspid valve > right ventricle
    • right ventricle > pulmonary SL valve > pulmonary trunk > pulmonary arteries > lungs
    • lungs > pulmonary veins
    •  > left atrium
  33. systemic circuit
    • left atrium > mitral valve > left ventricle
    • left ventricle > aortic SL valve > aorta
    • aorta > systemic circulation
  34. pathway of blood through the heart
    • equal volumes of blood pumped to pulmonary and systemic circuits
    • pulmonary circuit short, low pressure circulation
    • systemic circuit, long high friction circulation
    • anatomy of ventricles reflects differences (left ventricle walls 3x thicker than right and pumps with greater pressure)
  35. coronary circulation
    • functional blood supply to heart muscle itself: delivered when heart is relaxed, left ventricle receives most blood supply
    • arterial supply varies among individuals
    • contains many anastomoses (junctions): provide additional routes for blood delivery, cannot compensate for coronary artery occlusion
  36. coronary circulation: arteries
    • arteries arise from base of aorta
    • left coronary arty branches to anterior interventricular arty and circumflex arty: supplies interventricular septum, anterior ventricular walls, left atrium, and posterior wall of left venticle
    • right coronary artery branches to right marginal artery and posterior interventricular artery: supplies right atrium and most of right ventricle
  37. coronary circulation: veins
    • cardiac veins: collect blood from capillary beds
    • coronary sinus: empties into right atrium; formed by merging cardiac veins (great cardiac vein, middle cardiac vein, small cardiac vein)
    • several anterior cardiac veins empty directly into right atrium anteriorly
  38. great cardiac vein
    anterior interventricular sulcus
  39. middle cardiac vein
    posterior interventricular sulcus
  40. small cardiac vein
    inferior margin
  41. angina pectoris
    • thoracic pain caused by fleeting deficiency in blood delivery to myocardium
    • cells weakened
  42. myocardial infarction (heart attack)
    • prolonged coronary blockage
    • areas of cell death repaired with noncontractile scar tissue
  43. cardiac muscle of the heart
    • striated, short, branched, fat, interconnected
    • connective tissue matrix (endomysium) connects to cardiac skeleton
    • numerous large mitochondria
    • intercalated discs: junctions between cells, anchor cardiac cells
    • desmosomes prevent cells form separating during contraction
    • gap junctions allow ions to pass from cell to cell; electrically couple adjacent cells
    • gap junctions allow the heart to be functional syncytium (behaves as a single unit)
  44. absolute refractory period
    when no action potentials can occur during that period
  45. what are three differences from skeletal muscle
    • does not need nervous sytem stimulation, can start on its own
    • all cardiomyocytes contract as a unit, or none do
    • long absolute refractory period, prevents tetanic contractions
  46. coordinated heartbeat is a function of
    • presence of gap junctions
    • intrinsic cardiac conduction system : network of noncontractile cells, initiate and distribute impulses, coordinated depolarization and contraction of heart
  47. autorhythmic cells
    • have unstable resting membrane potentials due to opening of slow Na+ channels (continuously depolarize)
    • at threshold, Ca2+ channels open
    • explosive Ca2+ influx produces the rising phase of action potential
    • repolarization results from inactivation of Ca2+ channels and opening of voltage gated K+ channels
  48. three parts of action potential
    • pacemaker potential: repolarization closes K+ channels and opens slow Na+ channels > ion imbalance
    • depoalrization: Ca+ channels open > huge influx > rising phase of action potential
    • repolarization: K+ channels open > efflux of K+
  49. sequence of cardiac excitement
    • sinoatrial node
    • atrioventricular node
    • atrioventricular bundle
    • right and left bundle branches
    • subendocardial conducting network (purkinje fibers)
  50. sinoatrial node
    • pacemaker of the heart in right atrial wall
    • depolarizes faster than rest of myocardium
    • generates impulses about 75x a minute (sinus rhythm)
    • impulses spreads across atria and to AV node
  51. atrioventricular node
    • in inferior interatrial septum
    • delays impulses approximately 0.1 second because fibers are smaller diameter, have fewer gap junctions, allows atrial contraction prior to ventricular contraction
    • inherent rate of 50x per minute in absence of SA node input
  52. atrioventricular AV bundle of His
    • in superior interventricular septum
    • only electrical connection between atria and ventricles
    • atria and ventricles not connected via gap junctions
  53. right and left bundle branches
    • two pathways in interventricular septum
    • carry impulses toward apex of heart
  54. subendocardial conducting network (purkinje fibers)
    • complete pathway through interventricular septum into apex and ventricular walls
    • more elaborate on left side of heart
    • AB bundle and subendocardial conducting network depolarize 30x a minute in absence of AV node input
    • ventricular contraction immediately follows form apex toward atria
  55. arrhythmias
    • irregular heart rhythms
    • uncoordinated atrial and ventricular contractions
  56. fibrillation
    • rapid, irregular contractions
    • useless for pumping blood, circulation ceases, brain death
    • defibrillation to treat
  57. ectopic focus
    abnormal pacemaker
  58. Defectective SA node may cause
  59. extrasystole
    • premature contraction
    • ectopic focus sets high rate
    • can be from excessive caffeine or nicotine
  60. to reach ventricles, impulse must pass through
    AV node.
  61. heart block
    • few (partial) or no (total) impulses reach ventricles
    • ventricles beat at intrinsic rate - too slow for life
  62. extrinsic innervation of heart
    heartbeat modified by ANS via cardiac centers in medullar oblongata
  63. cardioacceleratory center
    sympathetic affects SA, AV nodes, heart muscle, coronary arteries
  64. cardioinhibitory center
    parasympathetic inhibits SA and AV nodes via vagus nerves
  65. electrocardiogram
    • composite of all action potentials generated by nodal and contractile cells at given time.
    • three waves: P wave, QRS complex, T wave
  66. P wave
    depolarization SA node > atria
  67. QRS complex
    ventricular depolarization and atrial repolarization
  68. T wave
    ventricular repolarization
  69. P-R interval
    beginning of atrial excitation to beginning of ventricular excitation
  70. S-T segment
    entire ventricular myocardium depolarized
  71. Q-T interval
    beginning of ventricular depolarization through ventricular repolarization
  72. heart sounds
    • two sounds (lug dup) associated with closing of heart valves
    • first as AV valves close, beginning of systole
    • second as SL valves close, beginning of ventricular diastole
    • pause indicates heart relaxation
  73. heart murmurs
    • abnormal heart sounds
    • usually indicate incompetetent or stenotic valves
  74. cardiac cycle
    • blood flow through heart during one complete heart beat. atrial systole and diastole followed by ventricular systole and diastole
    • series of pressure and blood volume changes
  75. systole
  76. diastole
  77. phases of cardiac cycle: 1
    • ventricular filling, takes place in mid to late diastole
    • AV valves are open, pressure low
    • 80% of blood passively flows into ventricles
    • atrial systole occurs, delivering remaining 20%
    • end diastolic volume(EDV): volume of blood in each ventricle at end of ventricular diastole
  78. phases of cardiac cycle: 2
    • ventricular systole
    • atria relax, ventricles begin to contract
    • rising ventricular pressure > closing of AV valves
    • isovolumetric contraction phase (all valves closed(
    • in ejection phase, ventricular pressure exceeds pressure in large arteries, forcing SL valves open
    • end systolic volume (ESV): volume of blood remaining in each ventricle after systole
  79. phases of cardiac cycle: 3
    • isovolumetric relaxation -early diastole
    • ventricles relax, atria relaxed and filling
    • backflow of blood in aorta and pulmonary trunk closes SL valves. causes dicrotic notch, ventricles totally closed chambers
    • when atrial pressure exceeds that in ventricles, AV valves open, cycle begins again at step 1
  80. cardiac output
    • volume of blood pumped by each ventricle in one minute
    • normal: 5.25 liters per minute
  81. cardiac reserve
    difference between resting and maximal cardiac output
  82. three main factors that affect SV
    • preload: degree of stretch of cardiac muscle cells before they contract
    • contractility: contractile strength at given muscle length, independent of muscle stretch and EDV
    • afterload: pressure ventricles must overcome to eject blood
  83. positive chronotropic factors
    increase heart rate
  84. negative chronotropic factors
    decrease heart rate
  85. ANS regulation
    • sympathetic nervous system activated by emotional or physical stressors
    • NE causes pacemaker to fire more rapidly

    • parasympathetic nervous system opposes sympathetic effects
    • acetylcholine hyperpolarizes pacemaker cells

    atral reflex: sympathetic reflex initiated by increased venous return, hence increased atrial filling
  86. chemical regulation of heart rate
    • hormones
    • epinephrine from adrenal medulla increases heart rate and contractility
    • thyroxine increases heart rate, enhances effects of NE and E
  87. other factors that influence heart rate
    • age: fetus has faster HR
    • gender: females faster than males
    • exercise: increases HR
    • body temp: increases with increased temp
  88. tachycardia
    • abnormally fast heart rate (over 100 bpm)
    • if persistent, may lead to fibrillation
  89. bradycardia
    • heart rate slower than 60 bpm
    • may result in grossly inadequate blood circulation in nonathletes
    • may be desirable result of endurance training