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108 Cards in this Set
- Front
- Back
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Langley originally defined the autonomic nervous system (ANS) as what?
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as consisting of nerve cells and fibers by which efferent impulses pass to tissues other than skeletal muscle.
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Is there a sensory component to the ANS?
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There is a sensory component of ANS. Sensory nerves innervating viscera are part of ANS. Sensory components establish reflex loops for smooth control of ANS (ex. baro and chemoreceptor reflexes).
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T or F:
Baroreceptor reflex maintains blood pressure in narrow range. |
True
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T or F:
Chemoreceptor reflex maintain O2 levels. |
True
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Explain the baroreceptor reflex.
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In bifurcation of common carotid artery, there is a region of thinning of common carotid (this region pulses when you squeeze it) that is richly innervated by autonomic fibers from petrosal ganglion at neck.
When blood pressure goes up, these sensory nerves activate. This is a bipolar neuron: one pole in carotid sinus and other pole in dorsal medulla. Brain processes the information and sends an efferent impulse to heart. (Slows heart and reduces contractility, letting blood pressure go down. If heart go down too much, sympathetic reflex speeds it up. |
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Explain the chemoreceptors of the carotid body and how they regulate breathing.
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They sense O2 levels in blood.
CO2 levels go up. CO2 go to dorsal medial medulla. Brain tells lung to breathe fast |
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What does the ANS regulate?
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Regulates activities not considered under voluntary control, below level of consciousness
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3 functions of the ANS.
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Actions of many smooth muscles
Extrinsic control of heart. Variety of metabolic processes including release of catecholamines, glucagon, insulin, and others |
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Give examples of bodily functions controlled by the ANS. (7)
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Respiration
Circulation Digestion Body temperature Metabolism Sweating Secretion of certain endocrine glands |
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What are the 2 divisions of the ANS?
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Sympathetic
Parasympathetic |
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Anatomic Distinction of Sympathetic And Parasympathetic depends on position of _____.
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ganglia.
Parasympathetic neurons are in brain (medulla) and sacral spinal cord. Sympathetic neurons are in the thoracolumbar spinal cord. All autonomic preganglionic neurons make synapses with clusters of neurons called ganglia |
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What is the difference b/t efferent and afferent pathways.
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Afferent (sensory or receptor neurons)and efferent (motor or effector neurons) are components of ANS that mediate reflex loops.
Efferent includes the sympathetic and parasympathetic systems. Afferent includes major sensory neurons and are found in the dorsal root ganglia. Afferent component is not as well understood as efferent component. They each utilize different neurotransmitter |
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T or F: The spinal cord has grey matter only.
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False, white matter also.
The spinal cord has the intermedial lateral cell column which has the origin of sympathetic preganglionic neurons which send axons through ventral root where they synapse on a ganglion. The ganglionic neurons send out postganglionic neuron to target cell (i.e. a visceral organ like the heart). The ganglion are found in a chain of ganglion that is close to spinal cord in paravertebral ganglionic chain. Sympathetic system has short preganglionics and long post ganglionic axons. |
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Long presynaptic acetylcholine fiber comes off of ____
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brain
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Short postsynaptic with _____ receptor goes to target organ.
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nicotinic
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The preganglionic neuron is ____and the postganglionic neuron is ____.
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long, short
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The postganglionic neuron is usually on _____ of innervated organ.
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surface
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Diffusion Effect Of The Sympathetic System
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When this axon comes out spinal cord, it goes up and down the chain to synapse on adjacent ganglion to have diffusion effect so one preganglionic neuron can stimulate neuron in multiple ganglion.
Have collateralization of terminals in ganglion so one can stimulate many ganglia giving global discharge of sympathetic system: this is useful for fight or flight. |
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T or F:
Activity of parasympathetic nervous system give discrete activation of specific organ |
True. not a global effect.
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Ganglia not only relay stations, but serve as integrated areas.
Have multiple ganglia on heart (not just one). Different ganglia control aspects of cardiac function through different pathways. Give examples . |
one controls cardiac rate
one controls AV conduction one controls myocardial contractility |
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to release adrenalin is what?
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Adrenergic.
Neuron with catecholamine (NorEP) is adrenergic (or noradrenergic). |
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on parasympathetic side, nerve with Ach and releases Ach would be ______
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cholinergic
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Tissue responsive to neurotransmitter is called _________or ________(they are activated or inhibited by NorEp or Ach).
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adrenoreceptive cholinoreceptive
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__________ drugs are where action mimic turning on sympathetic nervous system.
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Sympathomimetic
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____________ drugs (aka cholinomimetic) are drugs that mimic effect of turning on parasympathetic nervous system.
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Parasympathomimetic
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Opposite of mimicry is ____ _____
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block effect
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_________ inhibit action of sympathetic nervous system.
_________ inhibits action of parasympathetic nervous system. |
Sympatholytic Parasympatholytic
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All autonomic preganglionic neurons activate nicotinic receptors. What are the nomenclatures for these?
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Nn is nicotinic receptor on neuron.
Nm is nicotinic receptor on voluntary muscle cell |
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T or F:
Drugs can elicit direct and reflexive effects on body |
True
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The preganglionic neuron (be it parasympathetic or sympathetic) will release acetylcholine (Ach) and the receptor effected is _____.
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nicotinic
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In ________ nervous system, postganglionic neuron has norepinephrine and receptor that is activated depends on target system ( and receptors).
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sympathetic
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In parasympathetic nervous system, parasympathetic postganglionic releases _______ as does its preganglionics. This acetylcholine of the postganglionic influences a _______receptor.
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acetylcholine
muscarinic |
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Sympathetic system is most active when the body needs to react to changes in the internal or external environment: The requirement for sympathetic activity is most critical for what?
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temperature regulation
regulation of glucose levels rapid vascular response to hemorrhage reacting to oxygen deficiency |
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T or F:
Sympathetic nervous system is on continuously. |
True. basal tone. It varies minute to minute and from organ to organ.
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________system often acts as a unit to facilitate fight or flight.
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Sympathoadrenal
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Activation of sympathetic nervous system does what?
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increases blood pressure, increases heart rate, blood goes to skeletal muscle, blood vessel dilate, pupils dilate, and bronchioles dilate.
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In a controlled environment and in the absence of stress, sympathetics not needed for life. In _______________(using drugs to destroy sympathetic system), animals do just fine.
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chemosympathonectomy
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What is Fight or Flight?
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During rage or fright the sympathetic system can discharge as a unit--affecting multiorgan systems.
(Sympathetic fibers show greater ramification.) Sympathetic preganglionic fibers may traverse through many ganglia before terminiating at its post-ganglionic cell. Synaptic terminal arborization results in a single preganglionic fiber terminating on many post-ganglionic cells. This anatomical characteristic is the basis for the diffuse nature of sympathetic response in the human and other species. |
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Sympathetic Responses include what? (6 things)
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heart rate increases
blood pressure increases blood is shunted to skeletal muscles blood glucose increase bronchioles dilate pupils dilate |
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It is organized for discrete activation of localized target organ.
Its main function is conservation of energy and maintenance of organ function during periods of normal activity. See decrease in heart rate, blood pressure, enhanced GI mobility and secretion, emptying of bladder, and constriction of pupils. |
Parasympathetic system
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Parasympathetic responses include what? (6 things)
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slows heart rate
protects retina from excessive light lowers blood pressure empties the bowel and bladder increases gastrointestinal motility promotes absorption of nutrients |
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T or F:
Both parasympathetic and sympathetic innervate blood vessels |
False.
Blood vessels just get sympathetic activation- ( no antagonism is possible). |
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There are receptors on vascular smooth muscle. What happens if you turn it on, what happens if you block it?
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Turn it on- vasoconstriction
Block it -vasodilation |
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T or F
In heart and intestine, sympathetics and parasympathetics act on same effector cell for antagonist response. |
True
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In eye, sympathetics act by controlling radial muscle of eye. If contract radial muscle- pupil get ____.
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larger
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Parasympathetics affect different muscle (sphincter muscle). If contract sphincter muscles- pupil get ____.
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smaller
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T or F:
Sympathetics gives copious watery salivary secretion. |
False. Parasympathetics
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T or F:
Sympathetic activation gives thick viscous secretion. |
True
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ANS maintain constant internal environment to maintain homeostasis. In most cases, sympathetics and parasympathetics act as physiological _______
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antagonist
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Heart: Sympathetic _____cardiac rate. Parasympathetic _____cardiac rate.
Eye: Sympathetics ___pupil. Parasympathetics ____pupil. |
heart: accelerates/diminishes
eye: open/close |
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epi, norepi, dopamine, isoproterenol, dobutamine, ephedrine, phenylephrine are examples of what?
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sympathomimetics
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muscarinic agonist and antagonists, ganglionic blocking drugs, cholinesterase inhibitors effect which system?
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Parasympathetic nervous
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What are some mechanisms of actions of drugs that effect the ANS?
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interfere with synthesis of the neurotransmitter
Metabolic transformation by same pathway of precursor of the neurotransmitter Blockade of neuro uptake release of content at nerve terminal block release of neurotransmitter. mimic effect of endogenous neurotransmitter postsynaptically block effect of neurotransmitter postsynaptically. Inhibit enzymatic degradation |
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Give an example of a drug that Interferes with synthesis of the neurotransmitter.
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Drugs: hemicholinium, methyl para tyrosine
For example, on cholinergic side, hemicholinium interferes with synthesis of Ach. Precursor for biosynthesis of catecholamines is tyrosine (later on it is dopamine). Use structural analog of tyrosine (methyl para tyrosine) to inhibit biosynthesis of catecholamines on adrenergic side |
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Give an example of a drug that causes a Metabolic transformation by same pathway of precursor of the neurotransmitter
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Drugs: methyl DOPA
The biosynthetic enzyme of catecholamine aren't substrate specific. So, on adrenergic side, methyl DOPA (not DOPA) can be metabolized to methyl dopamine and methyl norepinephrine. Methyl norepinephrine gets released due to action potential, but don't have same activity of endogenous neurotransmitter. So, false transmitter blocked effect of sympathetic nervous system. |
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Give an example of a drug that causes blockade of neurouptake.
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Drugs:Cocaine, tricyclic antidepressants, reserpine
NorEp gets reuptaken - drugs can block reuptake. Cocaine blocks NorEp uptake. Tricyclic antidepressant drugs block reuptake of the neurotransmitter. Active transport process take NorEp from synaptic cleft to cytoplasm. Active transport take NorEp from cytoplasm to synaptic vesicle reserpine blocks that active transport process. |
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Give an example of Drugs that can cause release of content at nerve terminal
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Drugs:
Black widow toxin has cholinergic mimetic effect via release of Ach. Amphetamine is sympathomimetic - effect by release of catecholamines |
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Give an example of a drug that Blocks release of Neurotransmitter
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Drugs: Botulinum toxin, bretylium
Botulinum toxin prevents release of Ach. Bretylium blocks release of NorEp. |
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Give examples of drugs that Mimic effect of endogenous neurotransmitter postsynaptically
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Neurotransmitters: Muscarine, nicotine, phenylepinephrine, clonidine, isoproterenol
On cholinergic side, muscarine mimics muscarinic effects of Ach. Nicotine mimics nicotinic effects of Ach On adrenergic side, variety of receptor types: 1 receptor activation is mimicked by drug called phenylepinephrine. 2 receptor activation is mimicked by clonidine Isoproterenol mimics either receptor |
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Give examples of drugs that Block effect of neurotransmitter postsynaptically
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Neurotransmitters: atropine, curare, trimethaphan, phenoxybenzamine, propranolol
Muscarinic effects of Ach blocked by atropine. Nicotinic effects of Ach on skeletal muscle blocked by curare. Nicotinic effects at ganglia blocked by trimethaphan. On adrenergic side, receptor blocked by phenoxybenzamine. Receptors blocked by propranolol (a nonspecific blocker). |
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Give examples of drugs that cause Inhibition of enzymatic degradation
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Anticholinesterase drugs, monamine oxidase inhibitors
On cholinergic side, have anticholinesterase drugs. On adrenergic side, monoamine oxidase inhibitors. |
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What receptors are involved in SNS/PNS?
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α receptors
β receptors dopamine receptors (sympathetic receptors) muscarinic (M) receptors nicotinic receptors. |
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Ciliary epithelium produces aqueous humor through_____receptors. This fluid keeps the anterior chamber of the eye at the proper pressure to focus light onto the lens and to the retina.
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beta 1
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Sympathetic activity stimulates the ______receptors on the iris to contract longitudinally to pull the iris towards itself, concentrically opening the sphincter.
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alpha
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The ciliary muscle and sphincter are stimulated by parasympathetic neurons releasing acetylcholine (Ach), binding muscarinic (M) receptors. These muscles work by ?
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ciliary muscle pulls on the trabecular meshwork to open the canal of schlemm and drain the fluid.
ciliary muscle contracts the entire machinery to accommodate lens by relaxing its pull on the lens. sphincter contracts to constrict the pupil. |
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What is the major disease of the eye? What is the patho?
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glaucoma
can result in blindness. Pathophysiology of glaucoma- Increased pressure in the intraocular space due to increased production and decreased drainage of aqueous humor. |
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What are the 2 types of glaucoma? How is glaucoma treated?
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Open angled and closed angled.
Glaucoma is treated with cholinomimetics, beta-blockers, and epinephrine |
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What specific drugs are used to treat glaucoma?
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Cholinomimetics: The use of these agents is based on their chemistry. Tertiary amines such as pilocarpine and physostigmine are uncharged molecules and therefore pass easily through membranes. These two drugs have the same effect on the eye but through two distinct mechanisms.
Pilocarpine: direct muscarinic agonist passes easily through the cornea stimulates M receptors on the ciliary muscle and the sphincter muscle of the iris. This helps open the canal of Schlemm, and helps fluid reach it. Physostigmine: cholinesterase inhibitor passes easily through the cornea as well as the blood brain barrier. increases local Ach by blocking acetylcholinesterase, increasing ciliary muscle and sphincter contraction. Pilocarpine vs. Physostigmine: Pilocarpine, based on its own individual charge, does not cross the blood-brain-barrier quite as easily as physostigmine, so less central nervous system effects with pilocarpine. Therefore, pilocarpine is the drug of choice for glaucoma, and if a patient does not respond well, physostigmine can also be tried |
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What is Acetazolamide?
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Diuretic
Blocks carbonic anhydrase activity, no HCO3 can be made. Production of aqueous humor requires the presence of HCO3. Blocking HCO3 prevents production of aqueous humor. |
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What Beta blocker is used for treating glaucoma?
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Timolol is the beta blocker of choice for glaucoma.
blocks beta1 and beta2 receptors. Lack of the anesthetic effect of other beta blockers, Blocks the beta receptors of the ciliary epithelium, decreasing synthesis of aqueous humor w/o anaesthetizing the cornea and causing “asensory” trauma. Timolol happens to cross the cornea more effectively than the other beta blockers. |
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How does stress effect the pupil?
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So under high stress, sympathetics release NE. NE (alpha, beta) increases aqueous humor production, and dilates the pupil.
Once the stress is gone, the parasympathetics constrict the pupil and drain the anterior chamber. |
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Discuss the sympathetic vs parasympathetic effects on the lungs.
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Sympathetic activity- beta2 receptor stimulation bronchodilates the airways and decreases airway secretions.
Parasympathetic activity- Ach stimulates M receptors, bronchoconstrict the airways and also to increase airway secretions. In the lungs there are many other receptors and mediators affecting lung function, but these are not directly involved in the SNS/PNS system. |
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What causes bronchdilation?
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Sympathetic activity (EPI, Dopamine (DA)
Stimulate beta2, with: epinephrine (alpha1, alpha2, beta1, beta2) medium dose DA - exogenous beta2 agonists (albuterol) Causes bronchial smooth muscle dilation and decreased secretions in the lungs. Withdrawal of these agents or decreased sympathetic activity causes bronchiolar relaxation, and increases bronchiolar secretions. |
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The two main actions of the drugs affecting the lungs occur by what?
Two receptors involved in this control are what? |
affecting airway diameter,
affecting airway secretions. beta2 & M receptors |
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What 2 drugs can be used for emergencies where increased ventilation is required, but due to their systemic side effects, are not used for long term therapy?
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Epinephrine and Dopamine
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Why does Norepinephrine have little effect on the lungs?
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beta 1 specific
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What happens during bronchoconstriction?
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Muscarinic receptor activity results in decreased airway diameter with increased secretions.
Muscarinic drugs are not used for this action, as there is little indication for decreasing the diameter of the airways. |
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The antimuscarinic agent ________, a muscarinic receptor antagonist, is very effective in blocking muscarinic bronchoconstriction and increased secretion.
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ipratropium
It is a quaternary amine, therefore it crosses membranes poorly and is therefore excellent for inhalation and targeting to the lungs with minimal systemic side effects |
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What agents used in cardiology to stimulate M receptors?
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beta blockers are employed to slow heart rate instead.
Know that atenolol, metoprolol, are both beta1 specific, and therefore the best beta blocker for use in asthmatics Labetolol and carvedilol has both alpha and beta1 activity, carvedilol is used for CHF treatment because decreases afterload. Non-selective beta blockers can exacerbate an asthma attack |
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Dicuss sympathetic and parasympathetic actions on the heart.
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Sympathetic activity- beta1 receptor stimulation increases heart rate, contractility, AV nodal conduction and cardiac output.
Parasympathetic activity- muscarinic (M) receptor stimulation decreases SA nodal firing, decreases AV node conduction and decreases CO. |
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The activity of the heart is controlled through ___ and ____ receptors.
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beta 1 and M
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T or F:
1 stimulation of the heart increases heart rate, contractility and cardiac output. |
True.
Epinephrine, Norepinephrine, dopamine and isoproterenol all increase heart activity |
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Muscarinic agonists or cholinesterase antagonists increase ____, slowing the heart rate, decreasing contractility and decreasing AV nodal conduction velocity through the AV node
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Ach
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The complex system of blood vessels express alpha, beta, dopamine (DA), histamine and M receptors.
Discuss. |
Sympathetic- NE (alpha, beta1), and epinephrine(alpha1, alpha2, beta1, beta2) and dopamine (DA) are released,
alpha1 vasoconstricts vessels, mainly at the arterioles, to increase pressure/ cut off blood flow to unnecessary organs and shunt it to organs that need it. beta2 vasodilates skeletal vessel beds to increase blood flow to needed muscles. Also lowers vascular resistance overall, and therefore blood pressure. |
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What effect is seen with epi?
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alpha1- constricts arterioles and large arteries
alpha2- blocks central nervous system release of norepinephrine beta1- increase heart rate beta2 – dilates skeletal vessel beds Overall, you see increased HR, increased BP. |
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What effect is seen with norepi?
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alpha1- constricts arterioles and large arteries
beta1- increase heart rate, contractility Although alpha1 increases arterial pressure, baroreceptor reflex results in a subsequent decreased HR and beta1 vs vagus = vagus wins. Overall see increased pressure, decreased heart rate. |
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What effect is seen with Isoproterenol?
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(beta1, beta2)
stimulates heart through beta1 directly. beta2 stimulates vasodilation, leading to decrease in BP, stimulating the baroreceptor reflex and further stimulating heart rate. |
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What effect is seen with Dopamine?
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(alpha1, beta1, beta2, D1)
All effects are dose-dependent- if give a low dose, only see D1 activity in renal artery. medium dose results in skeletal vessel dilation and increased heart rate through beta1 and the baroreceptor reflex. High dose results in increased arterial pressure via alpha1. |
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What are alpha 1 agonists?
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Phenylephrine, methoxyamine are specific alpha1 agonists, which increase arterial pressure, stimulating the baroreceptor reflex and decreasing heart rate.
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What are Non-selective alpha2 antagonists?
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alpha2 receptors mainly affect the central nervous system.
This receptor is on the presynaptic sympathetic vessels in the CNS and are normally stimulated by NE which has alpha1 and alpha2 activities. The alpha2 receptor inhibits release of norepinephrine from the CNS. Phenoxybenzamine and Phentolamine are non-selective alpha-blockers, used to control hypertension and tachycardia associated with pheochromocytoma. Phenoxybenzamine bind to alpha1 irreversibly Phentolamine binds to alpha1 reversibly Good Effectiveness and Orthostatic hypotension |
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What is Prazosin used for?
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is an alpha1 specific antagonist which can be used as a second line agent for control of hypertension, and to treat urinary retention
Because phenoxybenzamine and phentolamine block alpha1 and alpha2 receptors, tachycardia is exacerbated with these drugs and can be problematic. However, these drugs are used to temporarily control the more dangerous malignant hypertension associated with pheochromocytoma until surgery can be performed. These drugs are preferred over prazosin because they block alpha1 more effectively. However, the exacerbation of tachycardia makes the use of these drugs temporary. |
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Stimulation of muscarinic receptors on blood vessels results in vasodilation through the production of ____ _____.
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nitric oxide
Thus, one side effect of muscarinic agonists or cholinesterase inhibitors is vasodilation, potentially leading to orthostatic hypotension. |
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Dopamine Agonist- three different mechanisms, concentration-dependent
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Low dose DA- dilates renal artery, increasing kidney perfusion.
Mid-dose DA- stimulates beta2 receptors as well, resulting in dilation of skeletal bed BV’s to decrease systemic resistance. High Dose DA- stimulate alpha1 receptors and blood vessels constrict, resulting in an overall increased blood pressure. At all three doses, low medium or high, the renal artery is dilated to increase perfusion of the kidney low dose DA = D1, Medium dose DA = beta2 High dose DA = alpha1 |
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T or F
Parasympathetic activity (M) stimulates GI motility, allows sphincters to open, and increase secretions. |
True
so Sympathetic activity (alpha, beta) slows GI motility, increases sphincter tone, and decreases GI secretions. |
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T or F:
DA receptor activation causes increased GI motility, stimulates secretion, and decreases sphincter tone. |
True
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Why must opioids be considered with GI function?
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opioids will promptly decrease GI motility, decrease secretions and increase sphincter tone, inducing constipation
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What receptors are involved in the GI system?
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The GI system expresses alpha/beta, DA receptors, M receptors, opioid receptors, and 5HT receptors
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Sympathomimetic drugs- Drugs acting on alpha/beta/DA receptors ____ _____ GI activity.
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down regulate.
These drugs decrease motility, decrease secretory activity, increase motility, and increase sphincter tone. |
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Antidopaminergic drugs such as the cisapride and metoclopramide are used extensively in hospital setting as what?
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antinausea and promotility agents
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Muscarinics do what to the GI system? Give an example.
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increase blood flow to the gut, increase motility, increase secretions of the GI tract.
Bethanechol has been used to stimulate the GI tract and increase secretions for digestion in diabetic nephropathies, or after surgeries that decrease vagal function, two conditions that lead to GI paralysis. |
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Give an example of an Antimuscarinic.
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Propantheline, a competitive muscarinic receptor antagonist is used to relax the smooth muscle of the GI tract, increases sphincter tone and decreases secretions.
This drug is used to decrease nervous stomach/irritable bowel syndrome. |
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T or F
Constipation is not a common side effect of opioids. |
False
Opioid receptors exist in high density in the GI tract, and directly mediate decreased motility, decreased secretion, and increased sphincter tone through the enteric nervous system and the central nervous system. These actions delay passage of the fecal mass and increased absorption of water. |
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Give an example of 5HT antagonist.
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Ondansetron- ondansetron is a 5HT antagonist.
Serotonin plays a role in the nausea and vomiting reflex. Ondansetron blocks GI serotonin receptors, and therefore prevents nausea and vomiting. Ondansetron is used for serious nausea and vomiting, such as post-op N/V that is resistant to the more common DA blockers such as cisapride and metoclopramide. Ondansetron is also used for the intractable nausea and vomiting associated with chemotherapy. |
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What are the sympathetic and parasympathetic effects of the bladder?
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Sympathetic: The alpha receptors prevent bladder contraction by relaxing the bladder, and contracting the internal sphincter.
Parasympathetic: Muscarinic receptors in the bladder stimulate bladder contraction and relax the internal sphincter. (Micturition Reflex) |
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Are Antimuscarinics used for glaucoma, why or why not?
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These are not used for glaucoma, as these agents would worsen glaucoma.
These agents are used to dilate the eye for eye exams. The prototype is atropine, which blocks muscarinic receptors. Others include homatropine, cyclopentolate and tropicamide. These drugs vary only in their duration of effect. Atropine lasts > 72 h, homatropine 24 h, cyclopentolate 10 h, and tropicamide .5- 4 h. The muscarinic receptor blockade relaxes the ciliary muscle, causing the lens to relax and "thicken", and also relaxes the iris sphincter, resulting in cycloplegia, and mydriasis. |
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The muscarinic agonist _______is used to stimulate bladder function in non-obstructive disease, such as diabetic neuropathy
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bethanechol
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The muscarinic antagonist __________is used to stimulate urinary retention in incontinence.
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propantheline
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The _____- antagonist prazosin and terazosin (longer half-life) can increase micturition by relaxing the smooth muscle of the internal sphincter, as well as the smooth muscle of an enlarged and therefore obstructive prostate.
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alpha
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