what does it mean"microvessels act directly on local blood vessels,dilating or constricting them
They (endothelium of b.v)secret factors like prostaglandin (f2-constrict) or e(dilate) the vessel
Thank you✌️.So the microvessels(i.e-arterioles,capillaries)secrete these substances to control the amount of blood coming in to that part/organ through the regional/local artery of that place/organ;depending on the need of the organ.
Prostaglandin is produced from the cell wall itself,they will prepare it when they need it it’s like preparing meal when you are hungry