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Pharmacology Tunes

Sympathetic Nerve System
Kiss the Receptor
Dock at the alpha-adrenergic receptors
Be our beta receptor!
Baroreceptor blues
Alpha receptors
Baroreceptor the reflex

 

"The very model of a" Sympathetic Nerve System
(in the style of Gilbert and Sullivan)

The sympathetic system is a very special place to be
It readies you for stressful situations and emergencies
The first is innervation of the glands and heart and smooth muscle
Preganglionic synapses at cholinergic receptor
The postganglionic fibers lead to secretion of Norepi
But at the sweat glands postgang fibers secrete acetylcholine
Another sympathetic nerve leads to adrenal medulla
With secretion of norepi and epi Ė if you are cool- uh . . .
But if youíre parasympathetic A-C-H is where itís at
The craniosacral division is its name, leave it at that
And now back to the sympathetic, who gets what information
Letís all look at the organs and their sources of innervation--

In short in learning what nerves do
you shouldnít let it get to you
this is the very model of the sympathetic nerve system.

Oh first there are the blood vessels with only sympathetic nerves
The penis, face, and tongue have symp and parasympathetic nerves
Noradrenergic neurons always maintain constant constriction
But outflow increase constricts vessels [decreasing relaxes them]
The heart has dual innervation (normally vagal control)
If BP rises parasympathetics have to come back in
And heart rate will accelerate if drugs cause falls in the BP
And pupils dilate, radial smooth muscle contracts, so you see
Accomodation wonít work out when treated with cycloplegics
Example is a block with atropine to cause a dilation.
A parasymp activity will cause you bronchoconstriction
And symp on GI tract function will stop your gut motility

But letís look at an exception
The salivary glands can have
An increased salivation for symp and para innervation

 

Kiss the receptor
(in the style of Sebastian, of The Little Mermaid)


Muscarinic
Agonists have several targets
M1, M3, and M5 stimulate phospholipase C
And you donít know why but M2 and M4 subtypes are inhibitory
To adenylate cyclase and calcium channels
K+ channel activation is something that they also do.
And all five subtypes are found in the bodies of me and you.

M1ís very key to the brain,
M2ís in heart, smooth muscle, and outer AN (autonomic nerve) ends
M3ís in smooth muscle and the glands
M4ís for motor-brain, M5ís in brain and iris.
Sha la la la lots of receptors
May be found in the very same kind of cell
For example M2 and M3 are in the bladder and intestinal smooth muscle

In the eyeball
Muscarinics lower pressure
And help absorb aqueous humor, as one way to treat glaucoma
And another way that Iím dying to say is adrenergic control
Here you block the formation of aqueous humor
Timololís a good example, also helps humoral reuptake
And if you want big eyes take some atropine
But not acetylcholine.

If you add A-C-H to the heart
And slow down your heartbeat AV may not conduct
Body Reflexes oppose this trend
ACH dilates vessels in periphery
ACH in the GI tract will make your tummy turn and increase secretion
Choline esters help your renals flush
And youíll get muscle contraction in respiratory

Shalalalalala eccrine glands will secrete more with muscarinic agonists
And with pilocarpine, muscarine, and oxotremorine your CNS might spaz

Slow your symptoms
Take a muscarinic agent
No it wonít cure your disease but it might help with your other drugs

(Like in myasthenia gravis)

But youíve got to give these locally
If you donít want problems in your whole body
Itís hard for GI to absorb these drugs, Bethanecholís ok
And helps with acid reflux
Use the pilocarpine on your eye and sometimes A-C-H for an eye surgery
Donít use atropine in glaucoma
Or youíll block muscarinics and raise eye pressure

Dock at the alpha-Adrenergic Receptors
(in the style of Otis Redding)

Sitting here, Iím alpha-1
Iíll be causing vasoconstriction
In vessels I will stimulate
PLC to raise DAG and IP3

And Iím stimulated by EPI and NEPI
Causing pupil dilation and sphincter constriction
Iím excitatory and ready, so come to me

My friend there is called alpha-2
She could inhibit or activate you
She stops adenylate cyclase
And lowers cyclic AMP levels

Yeah NEPI and EPI work her too
But sheíll stop your nerves and activate your vessels
Sheíll also inhibit your postsynaptics
Watch out in the cardiovascular CNS


Be our beta receptor!
(in the style of Lumiere of Beauty and the Beast)

Beta 1, Beta 2, Beta 3 for me and you
Stimulate adenílate cyclase and raise cyclic AMP
When you run, Beta-2, will have happy news for you
Your adrenals let out epi and your muscle vessels expand
And your glands, well they know, when you need to really go
And then lots of epi helps alpha kick in!
Then weíll preserve your blood, and activate your brain
Alpha 1, alpha 2, beta 2

If you want to work your heart, use beta 1 for a start
Beta-2 Ďs a vasodilator where epi works for you
Beta 3 helps you pee, and itís also in the fat

Baroreceptor blues
(in the style of Winnie the Pooh)

Iím just a baroreceptor
Inside your carotid artery
If you have some low blood pressure
Your brain wonít get messaged from little me
Everyone knows if that happens
The CNS starts sympathetic paths
Then I start up your heart
And your vessels

Alpha receptors
(to the tune of a classical melody, whose title I do not remember)

What are alpha receptors
Well they are vasoconstrictors
But if theyíre inhibitors
Youíll call them alpha 2
With clonidine, guanidine and
oral alpha-methyl-dopa
Youíll activate your alpha 2
And help to lower blood pressure

Through an IV
Alpha-2 vasoconstricts
Followed by some
Reflex vasodilation!
Affinity
Helps you see what happens next
Epinephrineís
Most potent for alpha!


Baroreceptor the Reflex
(another baroreceptor song in the style of Frosty the Snowman)

Baroreceptors
In carotid arteries
Will adjust the workings of your heart
When your bloodís down in your knees

When you are lying
On the ground they do not work
But when you stand up baby try your luck
And letís hope they do not shirk

When activated they increase
Your sympathetic nerves
To fire more and raise heart rate
And cause vasoconstriction

Whew!

You see the baroreceptors they can sense
BP falls and then they stop sending
inhibitory messages to your brain

If they donít work youíve got
Postural hypotension
If your sympathetic reflexes
Are blocked you will fall down