How body makes blood flow more into brain instead of foot?

The heart continuously pumps blood throughout the blood vessels. Blood vessels have valves that prevent the blood from pooling at the legs, see below:

When blood flow leave heart into Aorta with 3 branches coming out of the aortic arch

1) Brachiocephalic trunk
2) Carotid artery
3) Subclavian artery

How does body manage on how much blood flows into those 3 different branches?
Does they get equal amount of blood flow?
Blood should flow more into less resistance vessels, the longer path of vessels, the more resistance it gets.
Would blood flow more into brain based on this shorter distance and less resistance within vessels?

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

I found an article discussing the blood distribution/flow percentages of a healthy adult.

Please see the reference article below for further details.

Let assume those data (MRI Blood Flow data) to be standard under gravity on Earth.
Do you have any related study on how blood flow is being affected in space without gravity?

I would like to know on whether brain receives more or less blood flow without gravity as comparing gravity on Earth.

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

Without gravity, there is a redistribution of the blood, where more blood stays in the legs and less blood is returned to the heart, which leads to less blood being pumped out of the heart. Thus, prolonged exposure to microgravity that astronauts experience results in chronic physiological adaptations including skeletal muscle atrophy (weakening of muscles), cardiovascular deconditioning (lower heart rate), and bone demineralization (because bones no longer have to support the body against gravity).

https://www.nasa.gov/mission_pages/station/research/cciss_feature.html

Gravity helps blood flow from upper body into lower body, on the other words, more blood should stay in the legs and less blood is returned to the heart.

I don't understand on why more blood stays in the legs without gravity.

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

I think bio_man might be mistaken about the blood pooling in the legs in zero gravity,

In case of normal gravity

The human cardiovascular system is quite well adapted to the constant gravitational force of the Earth. When standing, vessels in the legs constrict to prevent blood from collecting in the lower extremities. The heart is not strong enough by itself to get the blood back up the veins in legs and back to heart. The human body relies on a second system to finish that task. This system involves small valves throughout the veins and muscle contractions from the skeletal muscles when we walk and move about. The valves close when blood starts to flow in one direction, so that blood in the veins can only flow in the direction back to the heart, which is up the legs.

When we squeeze leg muscles to walk, stand or move about, the muscles squeeze the veins and force the blood to get moving. Because of the valves, the blood can only move in one direction as it gets squeezed along. So it is a combination of blood pressure from the heart's pumping action, the valves, and muscle movement that gets the blood up the legs against gravity. If the valves malfunction, then the blood falls back down to some extent after every muscle contraction and begins to pool in the veins. This causes the veins to swell with blood, which can be painful and unsightly, and is known as varicose veins.



Thus diagram shows the effect of leg muscle contraction on blood flow valve leg muscle contractions.

Due to gravitational pooling, the greater part of blood volume in the upright human is below the level of the heart. However, when a standing person suddenly changes to the supine position, gravity no longer causes a shift in blood volume from the thoracic compartment to the legs and feet. Therefore, the blood volume in the thoracic (central venous) compartment as blood volume shift away from the legs. This increases preload on the heart, thereby increasing stroke volume, although the resulting increase in cardiac output will be tempered by a reduction in heart rate. It is also worth noting that the brain accounts only for 2% of body weight, yet it receives about 15–20% of cardiac output (CO).

In case of zero gravity

In the space environment, the usual head-to-foot blood pressure and tissue fluid gradients that exist during the upright posture on Earth are removed. The subsequent shift in fluids from the lower to the upper portions of the body triggers adaptations within the cardiovascular system to accommodate the new pressure and fluid gradients.

I would like to know more on how second system works to bring blood back to heart.

"The arteries are the vessels with the "pulse," a rhythmic pushing of the blood in the heart followed by a refilling of the heart chamber." would it be second system helps to pump blood from leg back to heart?

https://medlineplus.gov/ency/imagepages/19395.htm

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

The sentence after describes the second system.

The arteries are the vessels with the "pulse", it seems that is special organ, which like a second heart.
I would like to know more about this "pulse" organ.

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

By definition, an artery is a vessel that conducts blood from the heart to the periphery. As the heart beats, a pulse is created that is transferred mechanically to the arteries. The largest artery in the body is the aorta and it is divided into four parts: ascending aorta, aortic arch, thoracic aorta, and abdominal aorta.

The radial pulse is felt on the wrist, just underthe thumb.
I would like to know on what kind of organ is about to generate this radial pulse.
Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

https://medlineplus.gov/ency/imagepages/19395.htm

It is all derived from the initial heart beat, it just gets transferred to these blood vessels because the pressure is so strong.