Drugs Affecting the Sympathetic NS Flashcards
adrenergic agonists are aka
sympathomimetics
adrenergic agonists are drugs that
stimulate the SNS
sympathetic NS
describe the pre/post ganglionic fibers of the sympathetic NS
pre-ganglionic: short
post-ganglionic: long
where does the ganglion reside in the sympathetic division?
closer to the spinal cord or CNS
give 2 examples of SNS neurotransmitters
- norepinephrine
- epinephrine (catecholamines)
what is the vital requirement for the release of neurotransmitters?
A Ca2+ influx into the axon terminal
where are Beta-adrenergic receptors found?
on the postsynaptic effector cells
Beta 1 is primarily located in the
heart
Beta 2 is primarily located in
smooth muscle of
- bronchioles
- arterioles
- visceral organs
where are alpha- adrenergic receptors found?
pre & postsynaptically
alpha 1 is found on
postsynaptic effector cells
- smooth muscle of sphincter (GI & bladder)
- blood vessels
alpha 2 is found on
presynaptic nerve endings and the central nervous system
action of specific adrenergic receptor sites through agonist binding
alpha 1
- vasoconstriction
- increase BP
- increase muscle sphincter tone
action of specific adrenergic receptor sites through agonist binding
alpha 2
- inhibits NE & insulin release from the presynaptic terminals
action of specific adrenergic receptor sites through agonist binding
beta 1
- increased heart rate through SA and AV nodes
- increase force of myocardial contraction
action of specific adrenergic receptor sites through agonist binding
beta 2
- vasodilation = decrease in BP
- bronchodilation
- increase rate and force of heart contraction
- decrease GI tract motility
direct acting sympathomimetics bind directly to the
receptor for a physiological response
indirect-acting sympathomimetics stimulate the release of _________
catecholamines
catecholamines are released from…
storage sites in nerve endings
after indirect-acting sympathomimetics stimulate the release of catecholamines they
bind to receptors
what stimulates the release of norepinephrine from nerve endings to create a stimulating effect?
amphetamines
what drugs inhibit the reuptake of norepinephrine into the axon terminal?
- cocaine
- tr-cyclic antidepressants (TCA)
drugs inhibiting the reuptake of norepinephrine into the axon terminal results in a
prolonged stimulant effect
mixed-acting sympathomimetics can be described as both a
direct stimulation of receptor sites and release of catecholamines from nerve endings
adrenergic blocking agents are aka
antagonists or sympatholytics
adrenergic blocking agents produce what type of effect
an opposite effect of agonists
nonspecific beta blockers block what 2 receptors?
beta 1 & 2 receptors
cardio-selective beta blockers block what receptors?
specific beta 1 blockers located in the heart
Are there “functional” beta 2 adrenergic receptors in the heart?
YES
- they increase heart frequency and contractility
Knowing what effect stimulation of beta receptors in the heart will have,
then what would you anticipate to be the effect of cardio-selective blockade of the beta receptors on heart activity?
- decreased heart rate and contractility
