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heart pressure and valves opening/closing??? watch

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    i got this wrong on a past paper i just did,
    From the mark scheme it would appear: when there is high pressure in the ventricles and aorta, then the aorta's valve is open and the atrial-ventricular valves are closed.
    how can pressure be increasing in the ventricles as blood is leaving it???
    can anyone tell me when valves are open/closed to do with pressure?? any help would be much appreciated but please don't confuse me more than i already am (actually quite hard that!)
    thanks
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    What was the exact question? I'm confused too ...
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    valves are like doors... and respond to differences in pressure

    so if the atria have a higher pressure than the ventricles they cause the atrioventricular valves to open.

    if the ventricles have a higher pressure than the atria they cause the atrioventricular valves to close

    if the left ventricles have a higher pressure than the aorta they cause the semi-lunar valve to open

    if the aorta has a higher pressure than the left ventricle is causes the sumi-lunar valve to close

    valves prevent the backflow of blood
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    then the aorta's valve is open and the atrial-ventricular valves are closed.

    this occurs when the the ventricles are at a higher pressure than the atria and at a higher pressure than the pulmonary vein and aorta

    this occurs at ventricular systole... check me on that someone
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    Yeah, basically even though the pressure's high in both the aorta and the ventricle, if the pressure is lower in the aorta than the in the left ventricle the semi-lunar valves will open so blood can move from l.ventricle to the aorta.
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    pressure is building up in the ventricles because blood is entering them from the atria through the opened AV valves because the pressure in the atria is higher than in the ventricles, so slowly the pressure builds up in the ventricles as blood is entering and the space available is decreasing (the SL valves are closed) so then as soon as the pressure is greater then the ventricles than in the atria then the AV valves close and as soon as the pressure is greater in the ventricles than the aorta/pulmonary arteries then the SL valves open and the blood leaves so the pressure decreases again.
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    thats basically the Q, then theres another one just after that says, what causes the blood pressure increase at the point labelled B?
    sorry its in a word doc, didn't know how else to do it
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    (Original post by Loopz)
    thats basically the Q, then theres another one just after that says, what causes the blood pressure increase at the point labelled B?
    sorry its in a word doc, didn't know how else to do it
    Ooh I did that Q and I didn't get the 2 marks on it cos I got the ticks exactly opposite to what they were in the markscheme!
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    (Original post by Kiesha)
    Ooh I did that Q and I didn't get the 2 marks on it cos I got the ticks exactly opposite to what they were in the markscheme!
    yep me too :rolleyes:

    (Original post by kiesha)
    Yeah, basically even though the pressure's high in both the aorta and the ventricle, if the pressure is lower in the aorta than the in the left ventricle the semi-lunar valves will open so blood can move from l.ventricle to the aorta.
    now you come to mention it, the pressure in the aorta is a bit lower than in the ventricles.. i just looked at it and thought they're both high- that makes no sense. hmm yeah so that makes a bit more sense, thanks
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    (Original post by Revenged)
    then the aorta's valve is open and the atrial-ventricular valves are closed.

    this occurs when the the ventricles are at a higher pressure than the atria and at a higher pressure than the pulmonary vein and aorta

    this occurs at ventricular systole... check me on that someone
    yep i think that's right! thanks for the doors imagery- i'll be sat in the exam thinking of that!

    btw my friend reckons there will definitely be questions on blood groups and immunology as they're only come up once in the last four years, and that was in 2002!
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    Hehe that would explain why I got it wrong first time too, I didn't even notice that on the graph when I actually did it :p:
 
 
 
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