It is this cycle that causes what we think of as every day hair loss -- most people lose between 50 to 100 hairs each day. And on days when we shampoo, we tend to lose more, says Amy McMichael, M.D., a professor of dermatology at Wake Forest Baptist Health.
1 Cells where infection or other damage is occurring release substances like histamine that dilate the arterioles and thus increase blood flow in the area. [ 2  Link to discussion of inflammation. ]. 3  In most of the body, the flow of blood through a capillary is controlled by the arteriole supplying it.ontrol of the Capillary Beds. An adult human has been estimated to have some 60,000 miles (96,560 km) of capillaries with a total surface area of some 800â1000 m 2 (an area greater than three tennis courts). The total volume of this system is roughly 5 liters, the same as the total volume of blood.
The arterioles then divide further into capillaries. Capillaries are the smallest blood vessels and their walls are only one cell thick which allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuses through the capillary walls into the tissues that need it. This is aided by the relatively high blood pressure that also squeezes the oxygen and nutrients through the capillary wall and into the cells of the tissue. At the same time carbon dioxide and other waste products re-enter the capillary in order to be processed and removed from the body.