Lecture 7: ANS Flashcards
What is the difference between a preganglionic and postganglionic neuron?
Preganglionic starts in CNS, only has Ach for its NT
Postganglionic starts in autonomic ganglia, can use nictonic (Ach), muscarinic (Ach), or adrenergic (epi/norepi)
What is the function of the sympathetic nervous system and its other name?
Catabolic, fight or flight response
Thoracolumbar system
What is the function of the parasympathetic nervous system and its other name?
Anabolic, rest and digest
Craniosacral system
What is the key difference in response for the sympathetic and parasympathetic? Why does it occur?
Sympathetic is generally more widespread
Parasympathetic is localized
Sympathetic fibers are located farther from their target organ along the spinal column, while parasympathetic postganglionic neurons are right next to a target organ.
What is the primary NT secreted by postganglionic fibers of the sympathetic NS? What is the exception?
Norepi
The exception is the adrenal medulla, which is 80% epi & 20% norepi
What are the differences between epi and norepi?
Norepi is faster acting but has lower response in regards to beta stimulation.
What breaks down Ach?
Acetylcholinesterase
What are the monoamines?
Catecholamines, such as dopamine, epinephrine, and norepinephrine
What happens in the terminal pathway of monoamine creation?
Formation of EPI and NE
How are NE effects stopped?
Stopped mostly by reuptake of neuron it was secreted from.
Can also be inactivated by liver and brain enzymes.
What two enzymes metabolize/degrade EPI and NE?
COMT
MAO
What is the amino acid origin of dopamine?
Tyrosine
What is the monoamine synthesis pathway?
Tyrosine -> Dopa -> Dopamine -> NE -> Epi
Where do I find muscarinic and nicotinic receptors?
Muscarinic: GI tract, myocardium, blood vessels, exocrine glands, cerebral vasculature
Nicotinic: Skeletal muscle, adrenal medulla
What are the effects of a cholinergic agonist?
Eye: Miosis (pupil contraction)
Heart: Bradycardia
Respiratory: bronchial constriction + increased secretions
GI: increased motility
GU: relaxation of sphincters and bladder wall contraction
Glands: increased secretions
What is the mnemonic for cholingeric agonist effects?
DUMB BELS
Diarrhea
Urination
Miosis/muscle weakness
Bronchorrhea/bronchospasm
Bradycardia
Emesis
Lacrimation
Salivation/Sweating
What are the direct cholinergic agonists and their indications?
Bethanecol: Urinary retention
Pilocarpine: angle-closure glaucoma, miosis induction, Sjogren’s syndrome
Nicotine: Nicotine replacement therapy
What are the contraindications of direct cholinergic agonists?
Asthma, bradycardia/hypotension, CAD, epilepsy, GI inflammation/spasms, hyperthyroidism, parkinson’s, peptic ulcers, stroke, uncontrolled hypertension
What is the MOA and the PK of a direct cholinergic agonist?
Mimicking Ach and acting on muscarinic receptors.
Half life is <5 hours, dosed throughout the day.
What are the Acetylcholinesterase inhibitors and their indications?
Donepezil, Galantamine, Rivastigmine (Alzheimer’s)
Malathion: topical tx for lice
Alzheimer’s = the DRUGS are NOT for U, so DRG.
What is the common chemical characteristic of Alzheimer’s?
Low presence of Ach, which is why we use acetylcholinesterase inhibitors to prolong Ach.
What are the contraindications of acetylcholinesterase inhibitors?
Intestinal/urinary obstruction, bradycardia, or heart block. (Has powerful GI effects, so you need to titrate slowly)
Caution in GI ulcers, COPD, asthma, seizure, and CVD
What are the adverse effects of acetylcholinesterase inhibitors?
Muscle fasciculations and weakness in normal people.
Improve muscle strength in people with myasthenia gravis.
What is the key difference between acetylcholinesterase inhibtors vs cholinergic agonists?
Acetylcholinesterase inhibitors are designed to prevent Ach breakdown, so it lasts longer and exerts effects longer.
Cholinergic agonists simply work directly on receptors but still get broken down.