cardiac cycle

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  1. cardiac cycle
    • the period between the start of one heartbeat and the beginning of the next
    • fluids move from an area of higher pressurse to an area of lower pressure
    • the pressure within each chamber rises during systole and falls during diastole
  2. systole or contraction
    the chambers contracts pushes blood into an adjacent chamber or into an arterial trunk.
  3. diastole or relaxation
    chambers fills with blood and prepares for the next cardiac cycle
  4. correct pressure relationships depends on
    • the careful timing of contractions
    • the hearts elaborate pacemaking and conducting systems normally provide the required spacing between atrial and ventricular systoles
  5. when cardiac cycle begins all four chambers are
    • relaxed
    • and the ventricles are partially full with blood
  6. during atrial systole
    • the ventricals are completly filled with blood
    • blood cannot flow into the atria because artial pressure exceeds venous pressure
    • very little backflow into the veins because blood takes path of least resistance
    • then heart enter the atrial distole
  7. atrial diastole and ventricular systole
    • begin at the same time
    • ventricles push blood through the systemic and pulmonary circuits and toward the atria
    • the heart then enters the ventricular diastole
  8. ventricular diastole
    • filling occurs passively (due to gravity)
    • both the atria and ventricles are relaxed
    • the next phase is atrial systole which complets the filling of the ventricles
  9. when the heart rate increases all the phases of the cardiac cycle are
    • shortened
    • greatest reduction in time spent in diastole
  10. whats another word for atrioventricular valve
    av node
    tricuspid valve
  11. cardiac output (co)
    • a measure of how hard the heart is working
    • the volume of blood that is ejected from the left ventricle, into aorta each min
    • indication of the blood flow through peripheral tissues
    • co=sv*hr
    • sv- the amount of blood that leaves the heart per contraction
    • hr- heart rate (bpm)
  12. what effects heart rate`
    • autonomic innervation
    • hormones
  13. what effects stroke volume
    • end diastolic volume
    • end systolic volume
    • sv= edv-esv
  14. frank starting law
    • the relationshiip between the amount of ventricular stretching and the contractile force means that within physiological limits, increasing the edv results in a corresponding increase in stroke volume
    • "more in more out"
    • the more the heart is stretched the harder it will contract, forcing more blood out
    • cardiac output
    • venus return
  15. venus return
    60% of blood sites in veins at rest
  16. autonomic control
    • control center loacted in the medulla oblongta-  help monitor and control heart rate
    • recieves messages from parasympathic and sympathic system
  17. proprioreceptors
    • looks at body position
    • tells the body that its at rest so heart rate is low, but when body move it tells the body to speed heart rate up
  18. chemoreceptors  reflex (o2, co2,ph)
    • responds to changes in carbon dioxide,, oxygen , or ph levels in blood and cerbrospinal fluid.
    • sensory neuron
    • located in the carotied bodies, situated in the neck near the carotied sinus, and in hte aortic bodies, nerar the arch of the aorta
    • monitor the composition of arterial blood.
    • additional chmoerecptors loacated on the ventrolater surfaces of the medulla oblongata monitor the composition of csf
  19. baroreceptor reflexes
    • specialized recptors that monitor the degree of stretch in the walls of expanable organs.
    • pressure recptors  making sure the body have enoough blood pressure
    • adjust cardiac ooutput and peripheral resistance to maintain normal arterial pressures
  20. sympatheic nervous system
    • run from the medulla to sa node
    • norepinehren is the neurotransmitter in the sns
    • increase hr
    • increase in calcium entry , increasing the force of contraction
  21. parasympatheic nervous system
    • impulse travels via vagues nerve (x)- wondering nerve
    • release acetycholine
    • causes a hyperpolarization .of pacemaker cells
    • therefor slowing hr
  22. how hormones play  a role in chemical regulation
    epinephrin, thyroid causes increase in heart rate
  23. how do ions play a role in chemical regulation
    • calcuim increase hear rate
    • sodium and patassuim decrease heart rate
  24. other factors that invole in hr
    • age- hr in infants starts hig then slowdown  in mid life the increase in older adults
    • sex-males have higher hr
    • exercise- lowers resting heart rate
    • templ- increasing temp increases hr decrease in temp decrease hr
    • disease
Card Set:
cardiac cycle
2012-09-26 17:42:31
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