Glossary of terms used on this site

vasoconstriction is a physiological mechanism that reduces the diameter of the blood vessels.
It normally occurs as an immediate reaction to blood vessel lesions in order to stop the bleeding. It’s the first stage of haemostasis.

Vasoconstrictors (adrenalin) are substances that  narrow the blood-vessels. The clinical use of vasoconstrictors is to increase blood pressure or to locally reduce blood flow.
Adrenalin acts locally by reducing the resorption rate of the anaesthesia and by reducing blood loss.

increases the diameter of the vessels (vaso) through dilatation. This dilatation is  possible through relaxation of the muscles from the vessels walls (arteries and veins).

the upper part of the skull.