Module 5: Autonomic & Somatic Nervous System Pharm Overview Flashcards
Anatomic Classification of the SNS
- thoracolumbar (T1-L2)
-
Preganglionic fibers:
- SHORT: terminate in ganglia at paravertebral chains
- some longer: terminate in prevertebral ganglia
- i.e. in front of vertebrae
-
Postganglionic fibers:
- LONG: run to innervated tissues
Anatomic Classicification of the PSNS
- craniosacral
-
Preganglionic fibers:
- LONG: terminate just outside of the target organ
Anatomical Classification of the Enteric Nervous System
(ENS)
- neurons located in the walls of the GI system
- myenteric plexus
- network of nerves between the layers of the muscular propria of the GI system
- responsible for peristalsis among other things
- **Regulates MOTILITY**
- network of nerves between the layers of the muscular propria of the GI system
- submucus plexus
- regulates the configuration of the luminal surface
- **Regulates SECRETION**

The Neurotransmitters
-
Cholinergic:
- release ACh
- all preganglionic efferent and somatic fibers
- most postganglionic parasympathetic and few sympathetic fibers
- release ACh
-
Noradrenergic (adrenergic)
- release norepinephrine (noradrenaline)
- mostly postganglionic sympathetic fibers
-
Dopaminergic
- release dopamine
- peripheral sympathetic fibers
- Nitric Oxide
- Peptides
Drugs that Affect ACh Release
-
Botulinum Toxin:
- indications: upper motor neuron syndrome, migraine, excessive sweating, cervical dystonia, eye muscles spasm
- enzymatic rmoval of amino acids on SNAPs and VAMPs
- irreversibly block ACh vesicle release leads to muscle paralysis
- Black-widow venom (alpha latrotoxin)
- stimulates the release of ACh and increases muscle contraction
- when ACh is depleted you end up with muscle paralysis
- no therapeutic application yet
Botulinum Toxin
- drug that affects ACh release
- indications: upper motor neuron syndrome, migraine, excessive sweating, cervical dystonia, eye muscles spasm
- enzymatic rmoval of amino acids on SNAPs and VAMPs
- irreversibly block ACh vesicle release leads to muscle paralysis
Black-Widow Venom (alpha latrotoxin)
- drug that affects ACh release
- stimulates the release of ACh and increases muscle contraction
- when ACh is depleted you end up with muscle paralysis
- no therapeutic application yet
Fate of Neurotransmitters: Acetylcholine
- bind to receptors
- gets broken down by acetylcholinesterase
- very short half-life (fraction of a second)
Fate of Neurotransmitters: Catecholamines
- bind to receptors
- diffuse away
- reuptake
- metabolized by enzymes
Catecholamines
- dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline)
- increase heart rate, blood pressure, breathing rate, muscle strength, and mental alertness.
Monoamine Oxidase
involved in the metabolism of catecholamines
Catechol-O-Methyltransferase (COMT)
- involved in the metabolism of caetcholamines
Postsynaptic Regulation of Signals
2 Mechanisms:
- up or down regulation receptors
- ex: surgical denervation of skeletal muscle = proliferation of nicotinic receptors over all parts of nerve fiber
- Controlling through electric potential
- excitatory postsynaptic potential
- inhibitory postsynaptic potential
Presynaptic Regulation of Signals
- provide feedback via autoreceptors
- stimulation of alpha 2 decreases release of NE
- stimulateion of beta receptors facilitates release of NE
- G-proteins inhibit Ca2+ intake leads to inhibition of vesicular fusion
- Provide feedback via heteroreceptors
- activated by substances released from other nerve cells
Adrenergic receptors of the radial muscle of the iris
alpha1 = dilation
Adrenergic receptors of the ciliary muscle of the iris
Beta 2
relaxation for far vision (dilation)
Adrenergic receptors of the lacrimal glands
alpha 1
secretion
Adrenergic receptors of the Sailvary glands
alpha 1
secretion of potassium and water
Adrenergic receptors of the SA node of the heart
Beta 1 and Beta 2
increase heart rate
Adrenergic receptors of the atrial heart
beta 1 and beta 2
increase contractility and conduction velocity
Adrenergic receptors of the AV junction
beta 1 and beta 2
increase automaticity and propagation velocity
Adrenergic receptors of the Purkinje system of the heart
beta 1 and beta 2
increase automaticity and propagation velocity
Adrenergic receptors of the ventricles of the heart
beta 1 and beta 2
increase contractility
Adrenergic receptors of the coronary arterioles
alpha 1, alpha 2, and beta 2
constriction and dilation
Adrenergic receptors of the arterioles of the skin and mucosa
alpha 1 and alpha 2
constriction
Adrenergic receptors of the arterioles of the skeletal muscle
alpha, beta 2
dilation, constriction
Adrenergic receptors of the cerebral arterioles
alpha 1
constriction (slight)
Adrenergic receptors of the pulmonary arterioles
alpha 1 and beta 2
constriction, dilation
Adrenergic receptors of the mesenteric arterioles
alpha 1 constriction
Adrenergic receptors of the renal arterioles
alpha 1, beta 1, beta 2
constriction, dilation
Adrenergic receptors of the salivary gland arterioles
alpha 1 and alpha 2
constriction
Adrenergic receptors of the veins (systemic)
alpha 1, alpha 2, beta 2
constriction, dilation
Adrenergic receptors of the bronchial muscles
alpha 2
relaxation
Adrenergic receptors of the bronchial glands
alpha 1 and beta 2
decrease secretion, increase secretion
Adrenergic receptors of the stomach motility
alpha 1, alpha 2, beta 1, beta 2
decrease (usually)
Adrenergic receptors of the stomach sphincters
alpha 1
contraction (usually)
Adrenergic receptors of stomach secretion
alpha 2
inhibition
Adrenergic receptors of the liver
alpha 1 and beta 2
glycogenolysis and gluconeogenesis
Adrenergic receptors of the gallbladder and ducts
beta 2
relaxation
Adrenergic receptors of the acini of the pancreas
alpha
decrease secretion
Adrenergic receptors of the islet cells of the pancreas
alpha 2, beta 2
decrease secretion, increase secretion
Adrenergic receptors of the motility and tone of the intestine
alpha 1, alpha 2, beta 1, beta 2
decrease
Adrenergic receptors of the intestine sphincters
alpha 1
contraction
Adrenergic receptors of intestinal secretion
alpha 2
inhibition
Adrenergic receptors of renin secretion in the kidney
alpha 1, beta 1
decrease; increase
Adrenergic receptors of ureter motility and tone
Beta 1
increase
Adrenergic receptors of the detrusor muscle of the urinary bladder
beta 2
relaxation
Adrenergic receptors of the trigone and sphincter of the urinary bladder
alpha 1
contraction
Adrenergic receptors of the male sex organs
alpha 1
ejaculation
Adrenergic receptors of the pilomotor muscles of the skin
alpha 1
contraction
Adrenergic receptors of the sweat glands
alpha 1
localized secretion
Adrenergic receptors of the fat cells of the skin
alpha 2, beta 1, beta 2, beta 3
inhibition of lipolysis, stimulation of lypolysis
Adrenergic receptors of the pineal gland
Beta
melatonin synthesis