Describe some of the different ways that a drug can be either an agonist or an antagonist?


Stroke, also called cerebral vascular accident (CVA), occurs when the blood flow to part of the brain is disrupted. There are primarily

two categories of stroke, ischemic and hemorrhagic. The most frequent cause of stroke is a blockage (ischemic) of a blood vessel in

the brain. The blockage can have several causes but all with the same result, brain cell damage or death. Brain cells cannot survive

without a blood supply of oxygen and nutrients. Blockage of blood flow in the brain can be caused by a clot in a blood vessel

(thrombosis) of the brain, the movement of a clot from another part of the body (embolism) to the brain, or a severe narrowing of an

artery in the brain (stenosis). In a hemorrhagic stroke, a blood vessel in the brain bursts, bleeding into the brain (intracerebral

hemorrhage) or into the spaces surrounding the brain.


The signs and symptoms of stroke depend on the areas of the brain affected and the functions they control. The right cerebral

hemisphere controls the left side of the body and the left cerebral hemisphere controls the right side of the body. The symptoms of

stroke may be:

sudden numbness or weakness, especially on one side of the body

sudden confusion, difficulty speaking, or understanding speech

sudden difficulty seeing in one or both eyes

sudden trouble walking

sudden dizziness, loss of balance or coordination

sudden severe headache

paralysis, pain