topic 4 pt 2

• What sound is associated with the closure of the AV valves?

  Lub
• Where is the closure of the AV valves felt?

  In the 5th intercostal space
• What sound is associated with the closure of the semilunar valves?

  Dup
• How does the duration of systole compare to diastole?

  Systole is shorter than diastole
• What is the resting heart rate (HR) in beats per minute (bpm)?

  75 bpm
• What is the average heart rate range in bpm?

  60-100 bpm
• What is the duration of each cardiac cycle in seconds?

  0.8 seconds
• How long does systole last in seconds?

  0.3 seconds
• How long does diastole last in seconds?

  0.5 seconds
• What is the End Diastolic Volume (EDV) in ml?

  120 - 130 ml
• What is the End Systolic Volume (ESV) in ml?

  50 - 60 ml
• How is Stroke Volume (SV) calculated?

  SV = EDV - ESV
• If the EDV is 120 ml and the ESV is 50 ml, what is the Stroke Volume?

  70 ml
• What is Cardiac Output (CO)?

  The volume of blood ejected per ventricle per minute
• How is Cardiac Output (CO) calculated?

  CO = HR x SV
• What is the typical resting Cardiac Output (CO) value in ml/min?

  5250 ml/min or 5.25 L/min
• How can Cardiac Output (CO) change with physical activity?

  CO can increase to more than 20-30 L/min
• What is Cardiac Reserve?

  The difference between CO at rest and the maximum CO a person can achieve
• What factors can alter Cardiac Output (CO)?

  Factors that change HR and SV
• What are the two types of nerves that innervate the SA and AV nodes?

  Parasympathetic and sympathetic nerves
• What neurotransmitter is released by parasympathetic nerves to slow heart rate?

  Acetylcholine
• What is the dominant influence on heart rate at rest?

  Parasympathetic nerves
• What neurotransmitter is released by sympathetic nerves to increase heart rate?

  Noradrenaline
• What are some hormones that affect heart rate?

  Adrenaline, Noradrenaline, Thyroid hormones
• What are some other factors that can affect heart rate?

  Body temperature, Drugs, Sleep, Psychological factors
• What are the three factors that can affect stroke volume?

  Preload, Contractility, Afterload
• What is preload?

  The amount of ventricular stretch at the end of diastole
• What determines preload?

  End Diastolic Volume (EDV)
• What does Starling’s Law of the Heart state?

  The greater the filling of the ventricles, the greater is the emptying
• What is the major determinant of EDV and therefore preload?

  Venous return
• What factors affect venous return?

  Blood volume, Central venous pressure, Venous tone, Skeletal muscle pump, Respiratory pump
• What is contractility?

  The strength of ventricular contraction at any given preload
• What increases myocardial contractility?

  Positive inotropic agents
• What are some examples of positive inotropic agents?

  Sympathetic stimulation, Adrenaline, Noradrenaline, Digoxin
• What decreases myocardial contractility?

  Negative inotropic agents
• What is afterload?

  The amount of resistance the heart must overcome to open the semilunar valves
• What is the mean pulmonary arterial pressure for the right ventricle?

  15-20 mmHg
• What is the aortic pressure for the left ventricle?

  100 mmHg
• Why does the left ventricle have a higher afterload compared to the right ventricle?

  Because it has to generate more force to overcome higher pressure in the aorta
• What is a sign of an overworked heart?

  Left ventricular hypertrophy