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Cardiac Physiology- Lecture 2 Test

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5 Written Questions

5 Matching Questions

  1. Systole
  2. Chemical Regulation of the Heart
  3. Regulation of Stroke Volume
  4. Afterload- Back pressure
  5. Regulation of Heart Rate- Autonomic NS
  1. a 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
  2. b Contraction
    - ejection of blood
  3. c Back pressure of aortic and pulmonary valve must be over come by ventricle to open valves and eject blood
    -80 mm Hg (aorta)
    -8 mm Hg (pulmonary)
  4. d SV is the difference between
    -EDV- end diastolic volume
    -amt. of blood collects in the ventricle during diastole
    ESV- end systole volume
    -volume of blood remaining in ventricle after contraction
  5. e Autonomic NS Regulation (extrinsic factor regulating the heart)
    Under stress, fright, anxiety, excitement
    -sympathetic fibers release norepinephrine
    -binds to B1- andrenergic receptors
    -causes threshold to be reached quicker- pacemaker fires more rapidly faster beat

5 Multiple Choice Questions

  1. CO=HR x SV
    Cardiac Output (CO)- amt. of blood pumped by each ventricle in 1 minute
    -HR- heart rate
    -SV (stroke vol)- vol. of blood pumped by vent. per heart beat
    -correleated w/ force of ventricular contraction
  2. Ions influencing heart function
    -patients w/ hypocalcemia (low calcium)
    -depresses HR
  3. 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
  4. Contractility
    -inc. in contractile strength independent of muscle stretch and EDV
    More vigorous contractions due to...
    -greater Ca++ influx- from extracellular and SR
    Results- more blood ejected from the heart (lower ESV and greater SV)
    Contractility due to inc. sympathetic stimulation
    Norepinephrine and the B1 adrenergic receptors
    -stimulates whole process
    -inc. amt. of Ca+ in cell- how sympathetic NS inc. contractility
  5. Higher pressure is required to move through entire body. Right side pumps only to the lungs

5 True/False Questions

  1. Name 1 important intracellular parameter that can inc. contractilitySkeletal 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.


  2. Heart MurmursHeart Murmurs- leaky valve
    -blood generally flows silently
    W/ heart valve promblems
    -blood creates a "swishing" sound as it leaks backward or regurgitates through incompletely closed valves


  3. Cardiac Cycle- Phase 5- Ventricular SystoleVentricular 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


  4. EDV and ESV parametersEDV- 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. Stroke Volume (SV)SV (ml/beat) = EDV (120 ml)- ESV (50ml/beat)
    Therefore SV= 70 ml/beat
    Each ventricle pumps 70 ml of blood
    About 60% of blood in its chamber per beat


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