Question

Many choice: After eating a salty meal, which of the following would increase? Select one or more:

a. EDV

b. Stroke volume

c. HR

d. TPR

Answer 1

Answers are - a) EDV ( end diastolic volume )

b) stroke volume.

c) heart rate

High salt diet or saline infusion increases end diastolic volume which in turn increases stroke volume.

Salt intake decreases water excretion and increases water retention which increases blood volume. As blood volume is increased, there will be more venous return also which will increase preload on heart. Salt intake thus also increases blood pressure.

Stroke volume is the amount of blood pumped by each ventricle per beat.Ejection fraction is the fraction ( volume) of fluid ejected from chambers with each beat.Increase in venous return increases end diastolic volume increasing the stroke volume and hence preload on heart.Increase in preload increases the force of contraction as more blood has to be pumped effectively, so that extra amount of blood can be ejected to increase the stroke volume.

Salt has sodium, which increases inotropy of the heart due to increase in frequency of firing of cells as a result of faster conduction of ions across the cell membrane.