Diffusion movement is always (h->L/L->H)

There is a net movement of molecules from areas of high concentration to other areas. The average diffusion rate in a semi-solid like agar is around 50mm/h over the first net diffusion will always occur.

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blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.