Chemical Transmission in the Nervous System Flashcards
Action potentials are propagated down the neuron by the opening of
Na+ channels
tf these are a target for blocking NT release
How is excitation targeted pharmacologically at synapses?
blocking of Na+ channels prevents AP propogation and tf NT release
How is NT synthesis targeted pharmacologically at synapses?
targeting enzymes that produce NT
provide substrate or block activity
How is NT storage targeted pharmacologically at synapses?
vesicle storage and release
How is NT metabolism targeted pharmacologically at synapses?
enzymes that degrade NT
How is NT release targeted pharmacologically at synapses?
fusion of vesicles with membrane to release contents into synaptic cleft
How is NT degradation targeted pharmacologically at synapses?
enzymes that degrade NT; reuptake of NT by pre or post-synaptic membranes
How are receptors targeted pharmacologically at synapses?
agonists or antagonists for NT receptors; prejunctional receptors can alter NT release (e.g. a2-aR limits NA release)
The somatic nervous system is ________ and innervates
voluntary
skeletal muscle and overlying skin
the parasympathetic nervous system is _______ and innervates
involuntary (ANS)
heart, glands, and smooth muscle
the sympathetic nervous system is _______ and innervates
involuntary (ANS)
heart, blood vessels, glands (including sweat, adrenal)
What is unique about the SNS innervation at the adrenal gland?
it releases ACh rather than NA to stimulate adrenaline release
What are the two main chemical neurotransmitters of the peripheral nervous system?
ACh and NA
How is ACh synthesized?
- choline receptor on neurons transports dietary choline
- acetyl-CoA from mitochondria via choline acetyltransferase –> ACh
- ACh transported into vesicles via a carrier
- drugs can modulate synthesis and storage but are of limited clinical use
![](https://s3.amazonaws.com/brainscape-prod/system/cm/406/371/913/a_image_thumb.png?1659423380)
How is NA synthesized?
- tyrosine –> neurons via transporter
- broken down by tyrosine hydroxylase –> L-DOPA (L-dihydroxyphenylalanine)
- broken down into dopamine by DOPA decarboxylase
- dopamine can be the terminal product, or
- broken down by dopanine beta-hydroxylase to NA in synaptic vesicles
-
synthesis and storage can be modulated by drugs
- L-DOPA precursor drug can +dopamine production
- enzyme blockers can -dopamine and tf -NA synthesis
![](https://s3.amazonaws.com/brainscape-prod/system/cm/406/371/915/a_image_thumb.png?1659423382)
How is adrenaline synthesized?
- in adrenals, NA is converted to adrenaline
- via PNMT (phenylethanolamine-N-methyl transferase) in secratory vesicles
![](https://s3.amazonaws.com/brainscape-prod/system/cm/406/371/916/a_image_thumb.png?1659423382)