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The involuntary nervous system is also known as what?
Autonomic nervous system
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The autonomic nervous system consists of what two parts?
- Sympathetic nervous system
- Parasympathetic nervous system
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The voluntary nervous system is also known as what?
The somatic nervous system.
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The sympathetic and parasypathetic systems control what?
- Cardiac output
- Blood flow to organs
- Digestion
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The somatic nervous system controls what?
- movement
- respiration
- posture
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Adrenergic receptors are stimulated by what?
norepinephrine
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Cholinergic receptors are stimulated by what?
Acetylcholine
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What are the two types of cholinergic receptors?
- muscarinic (parasympathetic and sympathetic)
- nicotinic (parasympathetic, sympathetic, and somatic)
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What types of receptors are found in the sympathetic nervous system (fight or flight)?
- muscarinic (cholinergic)
- nicotinic (cholinergic)
- adrenergic
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What are the four types of adrenergic receptors?
- alpha 1
- alpha 2
- beta 1
- beta 2
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How is the activity of acetylcholine controled in cholinergic synapses?
Acetylcholine-esterase is in the synapse and it breaks down acetylcholine, returning the pieces to the pre-ganglionic fiber. The activity level is therefore controled by the amount of acetylcholine and acetylcholinesterase in the synapse.
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How is the activity of norepinephrine controled in adrenergic synapses?
Norepinephrine is controled by a negative feedback loop. NE stimulates alpha 2 receptors on the pre-ganglionic fibers which sends a message to slow or stop the release of NE into the synapes. This, in turn, limits the stimulation of alpha 1, beta 1, and beta 2 receptors on the post-ganglionic fiber.
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Alpha 1 stimulation results in:
- arteriolar constriction, resulting in increased peripheral resistance and increased blood pressure
- pupillary dilation (midriasis)
- sphincter contration in the bladder
- increased tension of smooth muscle around prostate
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Alpha 2 stimulation results in:
decreased sympathetic activity, therefore peripheral vasoliation
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Beta 1 stimulation results in:
- increased heart rate (chronotropic)
- increased force of contraction (inotropic)
- increased speed of conduction (dromotropic)
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Beta 2 stimulation results in:
- dilation of bronchioles
- dilation of arterioles and therefore decreased PR
- release of glucose from liver
- potassium shift into cells
- relaxation of detrusor muscle around bladder
- slowing of GI peristalsis
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How to alpha 1 and beta 2 stimulation affect PR?
Alpha 1 increases PR and Beta 2 decreases PR. The net effect is an increase in PR.
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What happens to the heart when muscarinic cholinergic receptors are stimulated?
- HR decreases
- speed of conduction decreases
- force of contraction decreases
- (similar to blocking of beta 1 receptors; also known as vagal nerve stimulation)
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What systems are effected and what happens when muscarinic cholinergic receptors are stimulated?
- heart rate slows, force of contraction decreases
- pupil constrics and intraocular pressure decreases
- GI system speeds up digestion
- tone of smooth muscle increases in bronchiol tree (can result in bronchospasms)
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What happens with excessive blockade of the muscarinic cholinergic receptors?
- Mad as a hatter (psychosis and seizures)
- Dry as a bone (decreased secretions)
- Blind as a bat (pupil can't constict or accomodate)
- Red as a beet (vasodilation)
- Hot as a hare (warm to touch)
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What happens when nicotinic receptors are blocked in the musculoskeletal system?
muscle paralysis
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Stimulation of which receptors causes increased conduction and contractility in the heart?
Beta 1 (and Beta 2)
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Stimulation of which receptors causes decreased condution and contractility in the heart?
muscarinic receptors
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Stimulation of which receptor causes blood vessels to contract?
Beta 2
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Stimulation of which receptors causes blood vessels to relax?
Beta 2 and muscarinic
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Stimulation of which receptor causes smooth muscle in lungs to relax?
Beta 2
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Stimulation of which receptor causes smooth muscle in the lungs to contract?
muscarinic
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Stimulation of which receptors decrease digestion in the GI tract?
Beta 2 and Alpha 1
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Stimulation of which recpetors causes increases digestion in the GI tract?
muscarinic
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Stimulation of which receptors causes urinary retention?
Beta 2 (relaxing bladder wall) and Alpha 1 (contraction of sphincters)
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Stimulation of which receptors causes urinary release?
muscarinic (contract bladder wall and relax sphincters)
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Stimulation of which receptors cause release and production of glucose?
Beta 2 (gluconeogenesis) and Alpha 1 (glucogenolysis)
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Stimulation of which receptors cause mydriasis?
Alpha 1 causes pupil dilation
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What drugs are muscarinic agonists?
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Bethanechol
- muscarinic agonist
- selective for GI tract and bladder
- used to help pt's gain control of bladder function, allows them to pee
- patient related variables include: asthma, peptic ulcers, heart conduction defects
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pilocarpine
- muscarinic agonist
- topical treatment for glaucoma
- causes pupil constriction and decreases intraocular pressure
- patient related variables include: asthma, peptic ulcers, heart conduction defects
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Common patient related variables for muscarinic agonists include:
- asthma (may precipitate bronchospasms)
- peptic ulcers (increases acid secretion)
- heart conduction defects (slows conduction)
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Muscarinic antagonists include:
- atropine/scopolamine/belladonna
- ipratropium quarternary amine
- dicyclomine
- oxybutynin
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atropine/scopolamine/belladonna
- competatively blocks muscarinic receptors
- used pre-operatively to decrease salivation, blocks vagal effects on heart, dilates pupils, treats bradycardia, reverses toxicity of too much muscarinic stimulation, prevents motion sickness (scopolamine patch)
- patient related variables include: BPH, high temperatures, reflux esophagitis
- too LITTLE can result in paradoxical bradycardia
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ipratropium quarternary amine
- blocks muscarinic receptors
- used in asthma/COPD to cause bronchodilation
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dicyclomine
- blocks muscarinic receptors
- decreases digestion, used for IBS
- patient related variables include: tachycardia, confusion, urinary retention, increased intraocular pressure
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oxybutynin
- blocks muscarinic receptors
- used to treat urinary incontinence r/t muscle spasms
- patient related variables include: tachycardia, confusion, increased intraocular pressure
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Nicotinic antagonist (neuromuscular blockers) include:
- atracurium (non-depolarizing)
- pancuronium (non-depolarizing)
- succinylcholine (depolarizing)
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atracurium or pancuronium
- non-depolarizing neuromuscular blocking agents (nicotinic antagonists)
- competatively blocks ACh
- used as adjunct to general anesthesia
- toxicity: respiratory paralysis (reversed by AChase inhibitors)
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succinylcholine
- depolarizing neuromuscular blocking agent (nicotinic antagonist)
- produces a persistent depolarization, preventing further stimulation
- CANNOT be revered by AChase inhibitors
- used for anesthesia, tracheal intubation
- avoid in patients with major burns, multiple traumas, h/o skeletal muscle myopathy, h/o malignant hyperthermia, as these can cause hyperkalemia and exacerbate toxicity
- toxicity: hyperkalemia
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Nicotinic and muscarinic agonists (AChase inhibitors)
- neostigmine
- organophosphate insecticides
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neostigmine
- AChase inhibitor (nicotinic, muscarinic agonist)
- reversibly blocks action of AChase
- used to reverse action of non-depolarizing neuromuscular blocking agents (atracurium/pancuronium), and to treat antocholinergic effects (mad as hatter, etc)
- toxicity (from excessive stimulation): nausea, vomiting, diarrhea, increased salivation, increased bronchial secretions, bronchoconstriction, bradycardia, muscle cramps, muscle fasciculation
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organophosphate insecticides
- irreversibly blocks action of AChase
- nicotinic/muscarinic agonist
- toxicity antidote: pralidoxime and atropine
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Adrenergic alpha agonists
- phenylephrine (Alpha 1)
- clonidine (Alpha 2)
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Mixed alpha/beta adrenergic agonists
- norepinephrine (alpha 1, alpha 2, beta 1)
- epinephrine (alpha 1, alpha 1, beta 1, beta 2)
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Beta adrenergic agonists
- dobutamine (beta 1)
- isoproterenol (beta 1, beta 2)
- albuterol, terbutaline, metraporterenol (beta 2)
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dopamine adrenergic agonists
- dopamine (dopa 1, dopa 2, beta 1, alpha 1)
- fenoldopam (dopa 1)
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isoproterenol
- stimulates beta 1 and beta 2
- used for testing purposes only (stress tests)
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metaproterenol
- stimulates beta 2
- used as a bronchodilator in asthmatics
- doesn't affect the heart
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dobutamine
- beta 1 agonists
- used to support cardiac function by increaseing rate and force of contraction
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dopamine
- at medium dose stimulates beta 1
- at high doses stimulates beta 1 and alpha 1
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norepinephrine
- stimulates alpha 1, alpha 2, and beta 1
- used to support cardiac function, is a potent vasoconstrictor
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epinephrine
- stimulates alpha 1, aplha 2, beta 1, and beta 2
- primary drug used in cardiac arrest, used to treat anaphylaxix, produce local vasoconstriction
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phenylephrine
- alpha 1 agonists
- topical decongestant
- given IV to support blood pressure
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ritodrine, terbutiline
- beta 2 stimulator
- inhibits uterine contractions
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clonidine
- alpha 2 similator
- decreases sympathetic outflow, may cause analgesia
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Toxicity from beta 1 stimulation:
tachycardia, cardiac ischemia, cardiac arrhythmias
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Toxicity from beta 2 stimulation:
hypotension, tremor
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Toxicity from alpha 1 stimulation:
hypertension, decreased organ perfusion
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Toxicity from alpha 2 stimulation:
orthostatic hypotension
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Patient related variables for beta 1 stimulation:
ischemic heart disease, heart conditions
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Patient related variables for alpha 2 stimulation:
hypertension, hypovolemia
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Adrenergic alpha blockers
- phentolamine
- prazosin, terzosin, doxazosin
- tamsulosin
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adrenergic beta blockers
propanolol
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phentolamine
- blocks alpha 1 and alpha 2
- used to reverse local vasoconstricting effect of extravasated alpha agonist
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prazosin/terzosin/doxazosin
- blocks alpha 1 receptor
- used for hypertension, BPH
- toxicities: orthostatic hypotension, nasal stuffiness, peripheral edema
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tamsulosin
- blocks alpha 1 receptors
- used to treat BPH
- toxicities: orthostatic hypotension
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propanolol
- blocks beta 1 and beta 2
- used to treat hypertension, angina, antiarrythmic
- toxicities: heart failure, bradycardia, bronchospasms (do not give SR as first dose)
- patient related variables: heart failure, asthma (better to give beta 1 selective agonist)
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