Cardio - Lec 7: Determinants of Cardiac Output & Mechanics of Systole and Diastole.

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  1. 3. the length-tension relationship of heart muscle allows for EQUILIZATION OF _______ from left and right heart sides. eg increased ______ from right heart --> increased filling of L ventricle --> increased stretch --> increased force development in L ventricle --> increased L ventricle __________.
  2. 5. MAP = diastolic pressure + 1/3x_________ pressure. _______ pressure is equivalent to Diastolic - systolic pressure. therefore MAP will be between systolic and diastolic pressure, but closer to diastolic.
  3. 6. increased _________ blood pressure --> increased afterload --> decreased ejection fraction (vol of blood ejected from heart). compensated because increased ESV --> increased EDV --> increased stretch --> increased force (good short term, not long term (hypertrophy).
  4. 9. (abb.) ____ = CO x TPR
  5. 10. the brain receives 10% of cardiac output. true or false?
  6. 11. ____________ heart failure (as in franks case) occurs when there is a bad preload (increased EDV without increase in cardiac output) --> eg left ventricular AV valve defect --> backup of blood in pulmonary circuit.
  7. 12. the heart receives approx 3-5% of cardiac output. true or false?
  8. 13. contractility is the force generated for any given ______.
  9. 14. the vessels that provide the most resistance to blood flow, and so have the greatest drop in pressure.
  10. 15. (abbreviation) total resistance to blood flow through entire circulation.
  11. 20. (3 words) the pressure gradient is equivalent to _______ _______ ________ . flow (cardiac output) = pressure gradient ( _______ _________ _________) / resistance.
  12. 25. the ______ receives approximately 27% of cardiac output, 21% via the GIT (portal vein) and 6% via the hepatic artery.
  13. 26. increased activity of the ____________ nervous system can modify contractility (and therefore increase stroke volume). can also be increased by increasing venous return.
  14. 27. cell length determines ________ of thick and thin filaments. cell length is determined by amount of blood in ventricle. normal cell length is LESS THAN MAXIMAL.
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  1. 1. (2 words) CO = HR x _________ ________ . ______ _______ = EDV - ESV (volume of blood ejected with each heart beat).
  2. 2. factors that affect stroke volume (and therefore cardiac output and MAP) are ___________ (capacity of muscle to produce force at a given length), venous return (preload --> EDV --> greater stretch on heart --> closer to optimum myocyte length). and afterload.
  3. 4. ___________ is determined by venous return. it is the force stretching the relaxed myocardium (end diastolic volume)
  4. 7. to increase force generated by heart muscle: increase intracellular Ca (20% from extracellular source through VOCCs, 80% from _____________ _______________).
  5. 8. (2 words) this relationshp in heart muscle is responsible for the very important equlization of output from right and left heart sides.
  6. 16. can increase stroke volume two ways: increase muscle length (by increasing venous return) or increase contractility (by increasing intracellular calcium by using __________)
  7. 17. in ____________ muscle, increasng the force of contraction can be done by increasing the number of fibres recruited, or the frequency of APs. (not cardiac muscle)
  8. 18. in cardiac muscle, action potential frequency is determined by __ node, and ALL fibres contract. so how do we increase the force of contraction?
  9. 19. normal length of the cardiac cells are less than the _______ length.
  10. 21. this catecholamine binds to the B-adrenergic receptor on cardiac muscle cells --> activates adenylate cyclase --> increases cAMP --> phosphorylates VOCC --> increases amount of Ca moving into cell --> increases release from SR --> over time more Ca stored in SR --> increased CB cycling and force.
  11. 22. the force opposing shortening of the myocardium during contraction. OR the force the heart must generate to overcome pressure in the great arteries (eg the higher the aortic pressure, the higher the afterload). also related to ventricular wall thickness.
  12. 23. flow rate of blood (or cardiac output) is proportional to the ___________ gradient / resistance (ie difference in ___________ increases flow rate, whereas resistance decreases flow rate)
  13. 24. the right heart --> pulmonary circuit --> left heart are arranged in series, while the systemic circuit is arranged in __________. much more resistance (so requires greater pressure gradient generated by L heart)