Blood flow in the feet

[Diana.s]

Mean Blood pressure in the ankles and feet while person stands reaches more than 100mm Hg. Mean arterial pressure in the aorta in also about 100mmHg. According to darcey's law, there is a blood flow providing a difference in pressure in the vessel. How blood travels from heart to the feet?

 

[Itoero]

On ‎10‎/‎12‎/‎2018 at 6:33 PM, Diana.s said:

Mean Blood pressure in the ankles and feet while person stands reaches more than 100mm Hg. Mean arterial pressure in the aorta in also about 100mmHg. According to darcey's law, there is a blood flow providing a difference in pressure in the vessel. How blood travels from heart to the feet?

This system involves small valves throughout the veins and muscle contractions from your skeletal muscles when you walk and move about.

[tinkerer]

2 hours ago, Itoero said:

This system involves small valves throughout the veins and muscle contractions from your skeletal muscles when you walk and move about.

Was the question not the opposite? You describe how gravity is overcome returning the blood upwards back towards the heart. The question was how does blood travel from the heart to the feet. Try hanging upside down for some protracted length of time to see how uncomfortably the heart then struggles to overcome gravity getting blood flow to the feet.

[Itoero]

12 hours ago, tinkerer said:

Was the question not the opposite? You describe how gravity is overcome returning the blood upwards back towards the heart. The question was how does blood travel from the heart to the feet. Try hanging upside down for some protracted length of time to see how uncomfortably the heart then struggles to overcome gravity getting blood flow to the feet.

Yes, I'm sorry I wrongly quoted. I just learned how it works.

[Janus]

On 12/10/2018 at 9:33 AM, Diana.s said:

Mean Blood pressure in the ankles and feet while person stands reaches more than 100mm Hg. Mean arterial pressure in the aorta in also about 100mmHg. According to darcey's law, there is a blood flow providing a difference in pressure in the vessel. How blood travels from heart to the feet?

 

Darcy's Law deals with pressure differences across a permeable membrane , in the absence of gravitational forces.    But is not the case between heart and feet.   Gravity is pulling down on the blood.   Blood flowing to the feet is aided by gravity to overcome the pressure difference, while blood going the other way fights gravity which cancels out the tendency for flow from hgh to low pressure.    Overall, it's a wash, and you don't have any restriction on circulation between heart and feet.  Besides, blood flow is pumped through the body by increasing the systolic  pressure above the mean.  The difference between mean and systolic pressure ( the pressure generated by the heart to push the blood) is greater than the difference between blood pressure in the feet vs the mean.

[tinkerer]

On 12/19/2018 at 7:12 AM, Itoero said:

Yes, I'm sorry I wrongly quoted. I just learned how it works.

Not to feel badly; it was not until I was in my 60s that I learned the veins returning blood from lower extremities are surrounded by tiny muscle structures which contract one following another, as the heart brings blood back upwards, against gravity. They act in effect as check valves, holding the blood between them when the diastolic (resting) part of the pulse presides, preventing a coursing up and down of the contents.

Truly amazing!