Now, hydrostatic pressure forces the cells of our body. And as blood travels, hydrostatic pressure for I'm sorry, capillaries run close to the cells of our body. And when the blood travels through the lumen of the capillary, hydrostatic pressure basically forces the nutrients and our waste products to move back and forth between the lumen and the cells fan around that capillary. Now, there are actually four ways by which the nutrients and waste products can be exchanged by the capillary. So let's discuss these four ways quickly. So, this is the cross section of the capillary.