blood flow has the highest velocity in arteries.
blood flow has the highest velocity in arteries.
where does blood flow have the highest velocity?
arteries
the mean velocity in the aorta varies over the cardiac cycle. during systole the mean velocity rises to a peak, then it falls during diastole. this pattern is repeated with each squeezing pulse of the heart. the highest velocities are found at the exit of the valve during systole. at this stage the majority of the flow can be described with velocity vectors normal to the entrance, but in plane velocities tangent to the flow are present. as the path starts to curve in the ascending aorta, the blood towards the outside of the arch tends to rotate towards the inner wall, causing a helical pattern that is observed in most individuals. as the blood moves into the aortic arch, the area with the highest velocity tends to be on the inner wall. helical flow within the ascending aorta and aortic arch help to reduce flow stagnation and increase oxygen transport. as the blood moves into the descending aorta, rotations in the flow are less present. physiological abnormalities due to plague formation or aneurysm lead to helical flows and high velocity flows in locations where they would not normally be present or as prominent. the abnormal high velocity areas generate a higher amount of wall shear stress than normal and contribute to stenosis and further plaque formation. abnormal helical structures expose tissue to low wall shear stresses that it would not normally experience. simulations of these flow patterns seek to identify what normal wall shear stress conditions and helical flows are present at specific location within the aorta.
hemodynamics of the aorta
rheoencephalography (reg), or brain blood flow biofeedback, is a biofeedback technique of a conscious control of blood flow. an electronic device called a rheoencephalograph [from greek rheos stream, anything flowing, from rhein to flow] is utilized in brain blood flow biofeedback. electrodes are attached to the skin at certain points on the head and permit the device to measure continuously the electrical conductivity of the tissues of structures located between the electrodes. the brain blood flow technique is based on non-invasive method of measuring bio-impedance. changes in bio-impedance are generated by blood volume and blood flow and registered by a rheographic device. the pulsative bio-impedance changes directly reflect the total blood flow of the deep structures of brain due to high frequency impedance measurements.
biofeedback