Although capillary walls are just a single layer of cells thick, they transfer nutrients (carried in the plasma, or the fluid part of the blood) and oxygen (transported by red cells) to adjacent tissues.
Kapillaaride vaid ühest rakukihist koosnevate seinte kaudu antakse lähedastele kudedele toitaineid (mida transpordib plasma ehk vere vedel osa) ja hapnikku (mida transpordivad punalibled).