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5 Written Questions

5 Matching Questions

  1. Atrial Brainbridge Reflex
  2. Cardiac Cycle- Duration
  3. Systole
  4. EDV and ESV parameters
  5. Chemical Regulation of the Heart
  1. a Sympathetic reflex caused by...
    -inc. in venous return
    -blood congestion in the atria
    Stretching of the atrial walls inc. HR and force by...
    -directly stimulating the SA node
    -stimulating by baroreceptors in the atria (pressure receptors)
    -triggers adjustment- inc. symptoms/stimulation of the heart
  2. b Length of cycle- .8sec
    -average 75 beats/min
    -atrial systole .1 sec
    -ventricular systole- .3 sec
    -remaining .4 total- heart relaxation termed "quiescent period"
  3. c Contraction
    - ejection of blood
  4. d Chemicals in blood and body fluids can alter cardiac function
    -epinephrine- released by adrenal medulla
    -enhances HR and contractility
    -Thyroxine- thyroid hormone
    -inc. metabolic rate and body heat
    -slow sustained inc. in HR
    -also enhances effects of epinephrine
  5. e EDV- two parameters (120 ml)
    1. length of ventricle diastole- how long is vent. relaxing?
    2. Venous pressure- how much pressure is there to bring blood into ventricle?
    ESV- two parameters(50 ml)
    1. atrial BP
    2. force of vent. contraction

5 Multiple Choice Questions

  1. Right side of heart- pulmonary side
    -systole- 24 mm Hg
    -diastole- 8 mm Hg
    Left side of heart- aortic side
    -systole- 120 mm Hg
    -diastole- 80 mm Hg
  2. Skeletal muscle at rest is near its optimal length for max. tension
    Cardiac muscle at rest is shorter...
    -therefore inc. stretch inc. contractile force
    Anything inc. vol. or speed of venous return- inc. SV
    -HR, exercise, etc.
  3. Both divisions of the autonomic NS send impulses to the heart
    The dominant influence is inhibitory termed 'Vagal Tone'
    -cutting the 'vagal nerve' (parasympathetic input removed) causes a quick inc. in beats/min
  4. True
  5. Atrial- systole and diastole
    ventricular- systole and diastole

5 True/False Questions

  1. Preload- Stretch of Cardiac Muscle"Frank- Starling Law" of the heart
    -Factor controlling SV is preload
    -Preload- or degree of stretch before the muscle contracts
    Stretch muscle fiber (and sarcomeres) inc. numbers of active across bridge (actin/myosin)
    All muscle if stretched is going to have a better contraction
    More muscle fibers stretched greater the force of contraction


  2. Cardiac Cycle- Phase 1(Atrial Systole)Ventricular Systole
    -atria relaxed- ventricles start contraction phase
    -ventricular pressure rises rapidly
    -Back pressure closes the AV valves
    -"isovolumetric Contraction Phase"
    -briefly ventricle closed off chambers and blood vol. is constant
    -Ventricular pressure exceeds pressure in arteries
    -semilunar valves are forced open
    -ends isovolumetric contraction phase
    -ventricular ejection phase
    -blood leaves ventricle and enters aorta and pulmonary trunk
    - aortic pressure reaches 120 mmHG
    -In left side of heart


  3. Stroke Volume Important Factors1. Preload- amt. vent. stretched by blood (affects EDV)
    2. Contractility- cardiac cell contractile force
    -Effects ESV- more cont.- less blood remains
    3. Afterload- back pressure exerted by blood in the large arteries leaving the heart
    -Effects ESV


  4. Cardiac Output- exampleCO (ml/min)= HR (75 beats/min) x SV (70 ml/beat)
    Normal blood volume- 5 Liters
    Entire blood volume through heart every minute
    Co is highly variable
    -altered by SV or HR or both
    Cardiac Reserve
    -maximal CO- Resting CO
    -Cardiac reserve (normally) 4-5 times greater than resting CO
    -Athletes about 7x greater than resting CO


  5. Regulation of HR- ParasympatheticParasympathetic NS
    -opposed to sympathetic responses
    -reduces HR when stress is relieved
    -Mechanism: Ach receptors(opens K+ channels)
    -Hyperpol. Cardiac cells
    -slows process down


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