Obj. 7: Cholinergic & Adrenergic Fibers, Neurotransmitters & Receptors Flashcards
What are the two main neurotransmitters of the ANS?
Acetylcholine (ACh)
and
Norepinephrine (NE)
Which axons release Acetylcholine (ACh)?
**All preganglionic axons **
& ALL parasympathetic postganglionic axons
Which neurotransmitter is released by cholinergic fibers?
Acetylcholine (ACh)
Which neurotransmitter is released by Adrenergic fibers?
Adrenergic fibers are a type of sympathetic postganglionic axons that release
**NE (and Epinephrine) **
What are the effects of neurotransmitters?
excitatory or inhibitory depending upon the receptor type
What are the two types of Cholinergic receptors that bind ACh?
**nicotinic **
&
muscarinic
Where did the names for muscarinic and nicotinic receptors come from?
The names came from drugs that bind to them and mimic ACh effects.
Where are Nicotinic Receptors found?
- Motor end plates (skeletal muscle)
- All ganglionic neurons of both sympathetic and parasympathetic divisions
- (site of synapse of preganglionic fibers)
- The hormone-producing cells of the adrenal medulla (NE & Epi)
What is the effect of ACh binding to nicotinic receptors?
ACh binding to nicotonic receptors is always stimulatory as it directly opens ion channels,
depolarizing the postsynaptic cell
Where are Muscarinic Receptors found?
Muscarinic Receptors occur on all effector cells stimulated by postganglionic cholinergic fibers (all parasympathetic and some sympathetic)
What is the effect of ACh binding to Muscarinic Receptors?
Can either be inhibitory or excitatory
depends on the receptor type of the target organ
What are the two types of Adrenergic Receptors (sympathetic postganglionic only) ?
Alpha and Beta
What are the subclasses for each of the alpha and beta adrenergic receptors?
alpha1
alpha2
beta1
beta2
beta3
What are the effects of NE binding to alpha adrenergic receptors?
generally stimulatory
What are the effects of NE binding to beta adrenergic receptors?
generally inhibitory
exception: NE binding to beta receptors of the heart is stimulatory