Bio 209 Ch 20B

  1. Define Cardiac Cycle
    Events associated with a heartbeat
  2. What are the events of a Cardiac Cycle
    • 1. Atrial Systole
    • 2. Ventricular Systole (Period of Isovolumetric Contraction)
    • 3. Atrial Diastole
    • 4. Ventricular Diastole
  3. What is EDV?
    End-Diastolic Volume: volume of blood at the end of disatolic systole
  4. What occurs during Ventricular Systole?
    • - Both ventricles contract
    • - AV Valves close
    • - Period of Isovolumetric Contraction
    • - Opening of Semilunar Valve
    • - Ejection of blood
  5. What causes the AV Valves to close?
    Back flow of blood
  6. What is Isovolumetric Contraction?
    Event in which ventricles contract and blood volume stays the same (because blood don't leave ventricles)
  7. What is the importance of Isovolumetric Contraction?
    It creates pressure within the ventricles, allowing blood to eject into the aorta and throughout the body
  8. What causes the Semilunar Valves to open?
    Higher pressure in L & R Ventricles than the Aorta & Pulmonary Trunk
  9. Do both ventricles eject the same amount of blood?
  10. What is ESV?
    End-Systolic Volume: amount of blood remaining at the end of a Ventricular Systole
  11. Define Stroke Volume
    Volume ejected per beat by each ventricle (EDV - ESV)
  12. Describe what occurs during Atrial Disatole
    • 1. BP is lower in Atria than in Veins
    • 2. Blood flows from Veins into Atria
    • 3. Blood in Atria increases and BP increases
  13. Describe what occurs in Ventricular Diastole
    • 1. BP decreases in Ventricles
    • 2. Blood flows back into Ventricles when Aortic pressure is higher than Ventricular pressure
    • 3. Semilunar Valve closes when blood flows back
    • 4. AV Valves open when Atrial pressure is higher than Ventricular pressure
    • 5. Blood flows from Atria to Ventricles when AV Valves open
    • 6. 3/4 of Ventricular filling occurs during Atrial Diastole
  14. What causes the AV Valves to open? Close?
    Open - Ventricular Pressure is LOWER than Atrial Pressure

    Close - Ventricular Pressure is HIGHER than Atrial Pressure
  15. What causes the Semilunar Valves to open? Close?
    Open - L & R Ventricle pressures HIGHER than Aorta and Pulmonary Trunk pressure

    Close - Back flow of blood from Aorta
  16. How does increased HR affect the Relaxation Period?
    Relaxation period decreases
  17. How does increased HR affect blood flow through the Coronary Arteries?
    Heart contracts more forcibly and requires more nutrients and oxygen
  18. How does blockage of Coronary Arteries cause Angina?
    If Coronary Arteries are blocked, blood flow during exercise may not be enough to supply cardiac muscle with enough Oxygen
  19. What is Ausculation?
    Listening to sounds within the body
  20. What causes heart sounds?
    Blood turbulance caused by closing of heart valves
  21. What causes the first heart sound (lubb)?
    Closure of AV Valves
  22. What causes the second heart sound (dupp)?
    Closure of Semilunar Valves
  23. What is a Heart Murmur?
    Abnormal heart sounds
  24. Define Stenosis
    Narrowing of the Mitral Valve
  25. Define Insufficiency
    Backflow of blood from Ventricle into Atrium
  26. What is Cardiac Output?
    Volume of blood ejected from a ventricle each minute
  27. Why does the heart rate increase as we exercise?
    The demand for oxygen and nutrients increases, therefore heart rate increases
  28. What is Stroke Volume?
    Volume of blood ejected from one ventricle with each contraction (EDV - ESV)
  29. Define Heart Rate (HR)
    Heart beats per minute
  30. What happens to the cardiac output if the stroke volume/heart rate increases?
    It increases
  31. What happens to the cardiac output if stroke volume/heart rate decreases?
    It decreases
  32. What is Cardiac Reserve?
    Difference between Cardiac Output at maximal exercise VS Cardiac output at rest (athletes have higher cardiac reserves)
  33. What affects the cardiac output's: Preload, Contractility & Afterload?
    • Preload: length of cardiac muscle fibers before contraction
    • Contractility: force of ventricular contraction
    • Afterload: pressure of blood in arteries
  34. How does increasing Preload increase the length of cardiac muscle fibers?
    Increasing cardiac fiber muscle length increases force of contraction
  35. How does increasing the length of ventricular diastole and increasing venous return affect preload and therefore cardiac output?
    Increasing length for ventricular diastole increases time for ventricular filling

    Increasing venous return increases EDV
  36. Define Positive Inotropic Agent
    Agents that increases contractiliy
  37. Define Negative Inotropic Agents
    Agents that decreases contractility
  38. Why does increased Afterload increase the work of the heart and EDV?
    More blood is left in the ventricle after ventricular systole and EDV increases
  39. How does a high EDV lead to congestive heart failure?
    If EDV is large, cardiac muscle fibers are stretched beyond optimal length, which in turn can cause blood to back up into lungs or systemic veins, due to decreased ventricular contraction/increased EDV
  40. What is Left Heart Failure?
    Condition in which Left Ventricles does not pump blood efficiently and possibly lead to pulmonary edema because of back flow of blood
  41. What is Right Heart Failure?
    Condition in which Right Ventricle does not pump effectively and can lead to backflow of blood into systemic veins, leading to peripheral edema
  42. How does the ANS affect HR?
    Medulla Oblongata receives input from: limbic system, proprioceptors, chemoreceptors and baroreceptors

    Sympathetic & Parasympathetic stimulation causes heart to increases & decrease
  43. What are some hormones that affect HR?
    Epinephrine, Norepinephrine, Thyroid Hormones
  44. What kinds of Cations affect HR?
    High levels of Na & K decreases HR

    High levels of Ca increases HR
  45. What are some factors that affect HR?
    Age: HR decreases with age

    Gender: females have slightly higher resting HR than males

    Exercise: daily exercising may decrease resting HR

    Temperature: heat (increases) & cold (decreases)
  46. What is Tachycardia?
    High resting HR
  47. What is Bradycardia?
    Low resting HR (less than 50 beats/min)
Card Set
Bio 209 Ch 20B
The Heart Part B