blockers (short for beta-adrenergic blocking agents) are drugs
that interfere with or "block" the function of certain neurotransmitters
in the brain, such as norepinephrine and epinephrine (also
known as adrenaline).
Normally, the body uses these neurotransmitters
to initiate emotional reactions to stress: increased heart
rate, increased breathing rate, increased blood flow to muscles.
Together, these reactions are called the "fight or flight"
response, and they prepare the body to deal with an emergency
or threat (typically by fighting or running away).
Beta blockers interfere with this process,
and so they can be helpful in curing stage fright, which is
an overreaction to a stressful but non-lethal situation, and
in treating migraines, which can be triggered by stress.
Because beta blockers lower blood
pressure and heartrate in general, they are also sometimes
used to treat high blood pressure and some forms of heart
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain