Question

Why does increasing the pressure gradient between arteries and veins in blood vessels cause an increase in blood flow?

Answer 1

everything flows from high pressure to low pressure according to physics. (let it be air, water, or blood, they all follow this rule)

higher the pressure difference (gradient) between the two, faster will be the flow.

let's explain this with the example of blood.

blood always flow forward from arteries to veins through capillaries.

arteries are high pressure system and veins are low pressure system.

normal arterial pressure during systole is around 120 mm Hg and during diastole it is around 80 mm Hg.

normal venous pressure is around 5 mmHg.

so during systole pressure gradient it 120-5= 115 mm Hg

during Diastole Pressure gradient is 80-5= 75 mm Hg

the value of pressure gradient is higher during systole...so the forward flow of blood will be faster during systole.

i hope this clear your doubt. (if its still not clear-

1) take an empty bottle , fill it with water, make a hole at the bottom- let the water escape from the bottle.

2) repeat the same experiment by applying pressure to the bottle- either by squeezing or by blowing air into the mouth of the bottle.

in which case the bottle get empties faster? it will be 2. )