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Heart question

Discussion in 'DAT Discussions' started by joonkimdds, Dec 10, 2008.

  1. joonkimdds

    joonkimdds Senior Member
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    3. Which of the following occurs during ventricular systole?

    A. Increased aortic pressure
    B. Increased ventricular volume
    C. Dup heart sound
    D. P wave

    answer is A and I don't understand why.

    All I learned at this stage is

    ventricular pressure goes up
    atria pressure goes down
    AV valve closes.

    And isn't ventricle supposed to eject blood from heart at this stage?
    To do so, it should open semiluar valve but if aortic pressure is higher than ventricle pressure, I think all the blood will back flow into the ventricle.
     
    #1 joonkimdds, Dec 10, 2008
    Last edited: Dec 10, 2008
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  3. Danny289

    Danny289 Member
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    pay attention to the question it is asking"during ventricular systole" that means blood is ejecting to aorta the result will be increasing blood pressure in aorta, the semilunar valve will be closed later.the anotomy of valves lead the closing in higher pressure of aorta actualy higher pressure in ventricle will open the valve toward aorta.
     
  4. joonkimdds

    joonkimdds Senior Member
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    Since aortic pressure is increasing, that means ventricle pressure is decreasing and that means ventricle volume should increase so doesn't it make B the correct answer too?
     
    #3 joonkimdds, Dec 10, 2008
    Last edited: Dec 11, 2008
  5. MediumDef

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    During this phase ventricular pressure will remain relatively constant as blood leaves the heart and the ventricular volume goes down.
     
  6. Streetwolf

    Streetwolf Ultra Senior Member
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    Why are you relating this to ideal gas laws?
     
  7. Katalyst

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    Increased Ventricular Volume occurs during Diastole. Recharging for the next pump. During Systole, The Ventricle squeeze and Ventricular PRESSURE is increased. This increase of pressure makes a wave (pump) that ejects from the heart into the aorta first.
     
  8. joonkimdds

    joonkimdds Senior Member
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    I was curious why I was relating it to ideal gas law when blood isn't gas, but when I read lecture slide from human physiology, it says

    "Blood flows from high to low pressure
    Pressure changes reflect changes in the volume of the chamber
    During contraction: ↓ volume/size = ↑ pressure
    During relaxation: ↑ volume/size = ↓ pressure"

    so I thought that maybe blood also has the same type of relationship as ideal gas law does.
     
  9. studlyguy87

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    Don't try to memorize what occurs during in each stage, but rather try to understand what is going on.

    So here you have a ventricular systole (ie. contraction of ventricles). You can deduce from this that the flow of blood must be from ventricles to pulmonary artery or aorta and hence get an increased aortic pressure. So (a) must be true. (b) is false because the heart is pumping blood out of ventricles so the ventricular volume must be decreased. (C) "Dub" sound comes from closing of semilunar valves so this must be also false. (d) P wave indicates that there is an atrial depolarization (ie. contraction of atria) thus, this is obviously false.
     
  10. polishp86

    polishp86 The Man, DDS
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    I like to think of the heart as a divided by a horizontal plane, right beneath the atria. Think of it as if the top half (atrias) contract first, and then the bottom half (ventricle) contract second. Then learn the order of contraction if it there were a vertical plane put into the heart divided into 4ths, this is in every bio and anatomy book, and easy to find online. Then understand valve closure order, don't think of it in terms of chemistry at all its just a totally different thing. after an aorta or ventricle contracts the pressure increases in the vessels that have the blood being ejected into them (this is why the aorta is an elastic artery, to be able to handle the stretching and high pressures of blood being ejected into it). think of each portion of the heart as a pump, and pressure increases after the pump, so that is where the pressure will be high in the heart, right after the vessel or pump. it cant be be B, systole means they're contracting and so ejecting theyre contents.
     

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