Turn on thread page Beta
    • Thread Starter
    Offline

    16
    ReputationRep:
    Why does central venous pressure in the heart determine end diastolic pressure?
    Also why does end diastolic pressure determine end diasotlic volume?
    Thanks
    • Study Helper
    Offline

    18
    ReputationRep:
    Study Helper
    Central venous pressure determines end diastolic pressure due to CVP leading to increased venous return. Increased venous return leads to more blood in the heart, subsequently more blood in the ventricles and thus higher pressure overall.

    If you increase the amount of blood in the ventricles (and thus increased end diastolic pressure), the ventricles are stretched more, leading to an increased volume. There's a reason that end diastolic pressure is sometimes called a "volumetric pressure".
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by Hype en Ecosse)
    Central venous pressure determines end diastolic pressure due to CVP leading to increased venous return. Increased venous return leads to more blood in the heart, subsequently more blood in the ventricles and thus higher pressure overall.

    If you increase the amount of blood in the ventricles (and thus increased end diastolic pressure), the ventricles are stretched more, leading to an increased volume. There's a reason that end diastolic pressure is sometimes called a "volumetric pressure".
    I though end volume meant volume of blood NOT volume of the chamber? so the increased volume of blood causes the increased pressure?
    thanks
    • Study Helper
    Offline

    18
    ReputationRep:
    Study Helper
    (Original post by jsmith6131)
    I though end volume meant volume of blood NOT volume of the chamber? so the increased volume of blood causes the increased pressure?
    thanks
    You're right. The volume of blood is what stretches the chamber to accommodate it by virtue of the pressure increase. When we refer to EDV we're thinking of the blood, but they increase with each other almost linearly. A 100ml container couldn't hold 110ml of fluid - the container has to expand to hold the extra. This idea is obviously scuppered in cardiac disease, though! Apologies that I didn't express myself well!
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by Hype en Ecosse)
    You're right. The volume of blood is what stretches the chamber to accommodate it by virtue of the pressure increase. When we refer to EDV we're thinking of the blood, but they increase with each other almost linearly. A 100ml container couldn't hold 110ml of fluid - the container has to expand to hold the extra. This idea is obviously scuppered in cardiac disease, though! Apologies that I didn't express myself well!
    Forgive my nagging but my lecture (for the second time) said that an increased end diastolic pressure CAUSES an increased end diastolic volume. Can you understand why he is saying this? Why does the increased PRESSURE cause an increased VOLUME?
    Thank you
    • Study Helper
    Offline

    18
    ReputationRep:
    Study Helper
    (Original post by jsmith6131)
    Forgive my nagging but my lecture (for the second time) said that an increased end diastolic pressure CAUSES an increased end diastolic volume. Can you understand why he is saying this? Why does the increased PRESSURE cause an increased VOLUME?
    Thank you
    More blood = More pressure = Expanded chamber = Blood fills more space (i.e. has a higher volume).
    Offline

    7
    ReputationRep:
    (Original post by jsmith6131)
    Forgive my nagging but my lecture (for the second time) said that an increased end diastolic pressure CAUSES an increased end diastolic volume. Can you understand why he is saying this? Why does the increased PRESSURE cause an increased VOLUME?
    Thank you
    Its actually that the increased Volume causes an increased Pressure.
 
 
 
Poll
“Yanny” or “Laurel”

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.