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68 Cards in this Set
- Front
- Back
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What type of nerves lack ganglia?
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Somatic motor neurons
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What type of nerves have dorsal root ganglia?
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Sensory neurons (note: there are NO synaptic connections within these ganglia)
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Describe autonomic ganglia.
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Contain cell bodies of post ganglionic neurons and is the site of synapse between the the pregang terminals and the post gang bodies/dendrites
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What's divergence?
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One preganglionic neuron synapsing on more than one postganglionic neuron
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What's convergence?
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Two or more preganglionic neurons synapsing on the same postganglionic neuron.
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What systems receive innervation from only the sympathetic nervous system?
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Piloerector muscles, sweat glands, and blood vessels (although some vascular beds, especially in the head and GU get parasympathetic innervation)
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What levels of the spinal cord do the sympathetic neurons originate from?
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T1-L2 "thoracolumbar"
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Name and describe the two types of ganglia associated with the sympathetic nervous system.
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Prevertebral - adjacent to cord in neck, affect the head and heart.
Paravertebral - found around the aorta, innervates GI and such. |
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What organ gets input directly from sympathetic preganglionics?
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Adrenal gland. Preganglionics pass through the celiac ganglia without synapsing and then innervate chromaphin cells.
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What levels of the spinal cord do parasympathetics arise from?
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The cranial nerves and S1-5.
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Acetylcholine structure?
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Norepinepherine structure?
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Epinepherine structure?
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Where neurons are cholinergic?
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1. All pre-ganglionic autonomic neurons.
2. Parasympathetic postgangionic neurons. 3. Somatic neurons at the neuromuscular junctions in skeletal muscle |
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What neurons release norepi (adrenergic)?
What are the exceptions to this rule? |
Sympathetic postganglionic neurons.
Exceptions: 1. sympathetic postgang innervating sweat glands release acetylcholine. 2. Chromaffin cells release epi and norepi. |
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How is the distinction made between parasympathetic and sympathetic?
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Anatomically
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What are the two types of cholinergic receptors?
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Nicotinic and muscarinic
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What type of receptors are nicotinic?
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Ligand gated ion channels
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Where are nicotinic receptors located?
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They're the primary receptor at all autonomic ganglia and the postsynaptic receptor on skeletal tmuscle. (distinct receptor subtypes)
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What effects does nicotine have on nicotinic receptors?
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It stimulates at low doses and blocks the receptors at high doses.
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What compound blocks both ganglionic and muscle receptors?
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Curarae
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What type of receptors are muscarinic?
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G-protein coupled
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Where are muscarinic receptors located?
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Parasympathetic end organs (at least 5 different subtypes)
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What compound blocks muscarinic receptors?
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Atropine
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Where are N(sub(n)) receptors located?
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Postganglionic neurons and some presynaptic cholinergic terminals
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What is the effect of ligand binding on the N(sub(n)) and N (sub(m)) receptor?
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Non-selective cation channel, depolarization
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Location of M(sub1) receptors?
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CNS neurons, sympathetic postgangs and some presynaptics
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Location of M(sub2) receptors?
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Myocardium, smooth muscle, and some presynatptics/CNS
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Location of M(sub3) receptors?
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Exocrine glands, vessels (smooth muscles and endothelium), and CNS
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Location of M(sub4) receptors?
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CNS, possibly vagal nerve endings
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Location of M(sub5) receptors?
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Vascular endothelium (especially cerebral) and CNS
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Effects of ligand binding on M(sub1) receptors?
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Formation of IP3 and DAG = increased intracellular calcium.
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Action of IP3?
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Release of Ca (causes muscle contraction)
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Action of DAG?
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Activates kinase C
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Action of adenylyl cyclase?
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Involved in cAMP production
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Effects of ligand binding on M(sub2) and M(sub4) receptors?
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Opens potassium channels, inhibits adenyl cyclase
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Effects of ligand binding on M(sub1), M(sub3), and M(sub5) receptors?
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Formation of IP3 and DAG = increased intracellular calcium
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What are the main subtypes of adrenergic receptors?
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Alpha and Beta
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Where are alpha1 receptors located and what's their main action?
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Located in smooth muscle and glandular tissue. Causes smooth muscle contraction.
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Where are alpha2 receptors located and what's their main action?
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Located on presynaptic nerve terminals. Inhits the release of norepi from postgang sympathetic neurons.
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Where are beta1 receptors located and what's their main action?
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Located primarily in the heart. Increases heart rate and contractility.
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Where are beta2 receptors located and what's their main action?
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Located primarily in smooth muscle. Causes smooth muscle relaxation.
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Where are beta3 receptors located and what's their main action?
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Located primarily in fat cells. Causes lipolysis.
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What is the effect of ligand binding to alpha1 receptors?
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Formation of IP3 and DAG = increases intracellular calcium.
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What is the effect of ligand binding to alpha2 receptors?
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Inhibition of adenylyl cyclase = decreases cAMP
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What is the effect of ligand binding to beta1 receptors?
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Stimulation of adenylyl cylcase = increases cAMP
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What is the effect of ligand binding to beta2 receptors?
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Stimulation of adenylyl cyclase = increases cAMP. Activates cardiac G (certain conditions only)
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What is the effect of ligand binding to beta3 receptors?
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Stimulation of adenylyl cyclase = increases cAMP
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Which beta receptors increase cAMP?
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All of them! (1, 2, and 3)
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What's the axonal pattern of sympathetic postganglionics?
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They occur in varicosities (wider junctional clefts)
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What's the result of transmitter being released from a chain of varicosities?
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Slower onset of effects often involving a large number of effector cells
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When end organs receive both sympathetic and parasympathetic innervation, what is the usual nature of the regulatory effects?
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Antagonistics (either on a common cell, like in the heart, or on different cell types, like in the eye)
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What happens with sympathetic stimulation of the eye? What receptors are involved?
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alpha1 - contracts iris radial muscles = mydriaisis (dilation)
beta2 - relaxes ciliary muscles = far focus of lens. Also = vasodilation which increases production of aqueous humor. |
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What happens with parasympathetic stimulation of the eye? What receptors are involved?
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muscarinic - contracts iris sphincter muscles (miosis) and ciliary muscles (near focus)
Also allow for drainage of aqueous humor |
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What happens with sinoatrial node stimulation?
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Sympathetics - positive chronotropic (increased HR)
Parasymp - neg chronotropic (dec HR) |
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What happens with AV node stimulation?
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Sympathetics - beta1 - positive dromotropic (inc conduction velocity)
Parasymp - neg dromotropic |
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What happens with ventricular muscle stimulation in the heart?
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Sympathetics - beta1 - positive inotropic (inc contractility)
Parasymp - anatagonizes sympathetic stimulation but without sympathetic tone activation has little/no effect. |
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What happens with stimulation of blood vessels?
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Receive only sympathetics (mostly).
Alpha1 - smooth muscle contraction Beta2 - Relaxation Parasymp only in face, tongue and GU - stimulation causes relaxation = vasodilation (via innervation of the endothelium when then releases NO) |
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What happens with stimulation of salivary glands?
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Sympathetics: alpha - weak increase in K and H2O secretion. Beta - weak inc in amylase secretion
Parasymp: pronounced inc in K and H2O secretion |
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What happens with stimulation of the lungs?
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Sympathetic: Beta2 cause bronchial smooth muscle relaxation = airway dilation
Parasymp: bronchial smooth muscle constriction and stimulation of gland secretion (via direct innervation of the smooth muscle) |
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What happens with stimulation of the GI?
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Sympathetic: Beta and alpha2 - decrease motility and tone. Alpha also contracts sphincters
Parasymp: opposite and stimulates glandular secretion |
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What happens with stimulation of the bladder?
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Sympathetic: alpha - contracts sphincter muscle. Beta - relaxes detrusor. (promotes filling)
Parasymp: contracts detrusor and relaxes sphincter |
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What happens with stimulation of the skin?
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Sympathetic: alpha contracts pilomotor muscles. Muscarinic activated by Ach cause generalized sweating.
Parasymp - little/no direct effects on skin |
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What happens with stimulation of the adrenal medula?
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Sympathetic - pregang directly synapse chromaffin cells with cause the release of epi and norepi into circulation
Parasymp - no direct effect |
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Most end organs prominant tone is parasympathetic via cholinergic receptors. Where is this not the case?
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Blood vessels - sympathetic adrenergic
Sweat glands - sympathetic cholinergic |
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What happens if you block ganglions to the...arterioles?
SA node? |
Vasodilation -> hypotension and increased peripheral flow
Tachycardia |
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What happens if you block ganglions to the...
Iris? Ciliary muscle? |
Pupil dilation (light sensitivity)
Accommodation paralysis (blurry vision) |
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What happens if you block ganglions to the...
GI? Bladder? Sweat glands? |
Reduced tone/motility (constipation)
Urinary retention (discomfort) No sweating (heat intolerance) |
