Term
| Most viscera has dual innervation by the ANS except what? |
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Definition
| Blood vessels which only have sympathetic innervation |
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Term
| What is the neural transmitter used at the preganglionic synapse of autonomic nerves? |
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Definition
| Acetylcholine (nicotinic receptors) |
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Term
| What is the neural transmitter used at the postganglionic synapse of autonomic nerves? |
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Definition
| Norepinephrine for for sympathetic (adrenergic) and acetylcholine for parasympathetic (muscarinic), adrenal medulla releases epinephrine into the blood which target adrenergic receptors |
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Term
| What are the exceptions of neurotransmitter receptors in the ANS? |
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Definition
| Thermoregulatory sweat glands are controlled by the sympathetic nervous system, postganglionic neurons release acetylcholine (muscarinic) instead of norepinephrine |
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Term
| What are the two types of acetylcholine receptors? |
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Definition
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Term
| Which muscarinic receptors are coupled to Gq/11 activation of PLC? |
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Definition
| Odd muscarinic receptors - M1, M3, M5 |
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Term
| Which muscarinic receptors are coupled to Gi inhibition of adenylate cyclase? |
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Definition
| Even muscarinic receptors - M2, M4 |
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Term
| What are the characteristics of M1 receptors? |
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Definition
| Found in autonomic ganglia, presynaptic terminals, CNS neurons, increases IP3 and DAG or increases intracellular calcium to modulate neurotransmitters |
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Term
| What are the characteristics of M2 receptors? |
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Definition
| Found in cardiac tissue and presynaptic/postsynaptic nerve terminals, decreases potassium influx or decreases cAMP to slow heart rate and conduction |
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Term
| What are the characteristics of M3 receptors? |
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Definition
| Found in smooth muscle, glands, endothelium, and vascular smooth muscle, increases IP3 and DAG, intracellular calcium, nitric oxide formation, or cGMP to contract smooth muscle, stimulate glandular release, and mediate vasodilation |
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Term
| What are the characteristics of nicotinic receptors (ligand gated ion channels)? |
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Definition
| Either Nm (muscle type) or Nn (neuron type), increases sodium influx to either contract muscle (Nm) or excite postganglionic neurons (Nn) |
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Term
| What is the primary location of alpha-1 adrenergic receptors? |
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Definition
| Postjunctional smooth muscle (contraction) via Gq receptor stimulation of phospholipase C |
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Term
| What is the primary location of alpha-2 adrenergic receptors? |
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Definition
| Presynaptic neurons, postsynaptic tissue, and blood platelets via Gi receptor stimulation of adenylcyclase |
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Term
| What is the primary location of beta-1 adrenergic receptors? |
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Definition
| Heart (stimulation) via Gs receptor stimulation of adenylcyclase |
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Term
| What is the primary location of beta-2 adrenergic receptors? |
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Definition
| Bronchial, uterine, and vascular smooth muscle (relaxation) via Gs receptor stimulation of adenylcyclase |
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Term
| What is the primary location of beta-3 adrenergic receptors? |
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Definition
| Causes lipolysis in adipose |
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Term
| What is the mechanism of action of alpha-1 receptors? |
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Definition
| Increases IP3 and DAG for vasoconstriction, contraction of smooth muscle, and inhibition of renin secretion. Also stimulates glycogenolysis and gluconeogenesis |
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Term
| What is the mechanism of action of alpha-2 receptors? |
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Definition
| Decreases cAMP to inhibit norepinepherine release from presynaptic terminals, leads to vasoconstriction and a decrease of insulin secretion |
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Term
| What is the mechanism of action of beta-1 receptors? |
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Definition
| Increases cAMP to increase heart rate, contractility, and conduction, increases the secretion of renin |
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Term
| What is the mechanism of action of beta-2 receptors? |
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Definition
| Increases cAMP to relax smooth muscle, increase skeletal muscle contractility and uptake of potassium, increases insulin secretion, glycogenolysis, and gluconeogenesis |
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Term
| What is the mechanism of action of beta-3 receptors? |
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Definition
| Increases cAMP to cause lipolysis |
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Term
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Definition
| Constriction of the pupil in response to high levels of light, mediated by an increase in parasympathetic tone causing contraction of the constrictor pupillae (mediated by M3) |
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Term
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Definition
| Dilation of the pupil in low light conditions, mediated by increase in sympathetic tone and contraction of the dilator pupillae (mediated by alpha-1) |
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Term
| How does the eye accommodate for near vision? |
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Definition
| Contracting ciliary muscle via parasympathetic M3 receptors, slackens suspensary ligament attached to the lens and allows lens to become rounded |
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Term
| Muscarinic antagonists may have what effect on vision? |
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Definition
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Term
| What is the aqueous humor? |
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Definition
| Watery fluid in the anterior chamber of the eye continuously produced by the ciliary epithelium, drains out of the eye via the trabecular meshwork and then into the canal of Schlemm |
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Term
| How is the aqueous humor controlled? |
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Definition
| Predominantly via the sympathetic nervous system, constriction via alpha receptors reduces secretion, dilation via beta-2 receptors increases secretion |
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Term
| What is the primary characteristic of glaucoma? |
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Definition
| Excess intraoccular pressure which may ultimately damage the eye |
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Term
| What types of drugs may be used for the treatment of glaucoma? |
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Definition
| Muscarinic agonists and acetylcholine esterase inhibitors enhance drainage, beta antagonists and alpha agonists reduce aqueous humor secretion |
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Term
| What controls lacrimal secretions? |
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Definition
| Parasympathetic innervation via facial or VII cranial nerve via M3 receptor |
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Term
| What type of receptors are found in tracheal and bronchiolar smooth muscle? |
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Definition
| Parasympathetic only but both muscarinic (bronchoconstriction via M3) and adrenergic beta-2 (bronchodilation) |
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Term
| What mediates glandular secretion in the bronchial glands? |
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Definition
| Mostly parasympathetic control - stimulated via M3 receptors, sympathetic stimulation through alpha agonists reduce secretion whereas beta-2 agonists increase secretion |
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Term
| How does the vagus (peripheral nervous system) stimulate the heart? |
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Definition
| Right vagus innervates SA node, left innervates AV node, vagus also innervates atrial muscles |
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Term
| How is the sympathetic nervous system involved in innervation of the heart? |
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Definition
| Included in the conduction system of the heart, found in both atrial and ventricular muscle |
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Term
| What are the four parameters that determine the effects of drugs on blood pressure? |
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Definition
| Direct effects on the heart, vascular effects, redistribution of blood, reflex phenomena |
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Term
| What sympathetic receptors are found in the heart and what are their effects? |
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Definition
| Beta 1 and Beta 2 receptors, increases activity |
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Term
| What parasympathetic receptors are found in the heart and what are their effects? |
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Definition
| M2 receptors, decreases activity (absent in His-Purkinje system unlike sympathetic fibers) |
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Term
| How does the parasympathetic nervous system mediate dilation in arterioles? |
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Definition
| No direct stimulation, stimulates M3 receptors in the endothelium to release endothelium derived releasing factor which leads to vasodilation. No parasympethetic stimulation in veins or renal arterioles |
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Term
| What is the baroreceptor reflex? |
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Definition
| Provides a negative feedback loop in which an elevated blood pressure reflexively causes heart rate to decrease, causing blood pressure to decrease. A decreased blood pressure activates the baroreflex, causing heart rate to increase thus causing an increase in blood pressure |
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Term
| What is the dominant mediator of tone in the GI tract? |
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Definition
| Parasympathetic tone, increases GI motility and secretion |
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Term
| What parasympathetic receptors are found in the smooth muscle of the GI tract? |
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Definition
| M3 in walls (contracts) and M2 in sphincters (relaxes) |
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Term
| What sympathetic receptors are found int he smooth muscle of the GI tract? |
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Definition
| Alpha-2, Beta2 in walls (relaxes) and alpha-1 in sphincters (contracts) |
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Term
| What receptors increase and inhibit secretion in the GI tract? |
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Definition
| Alpha-2 (sympathetic) inhibits, M3 (parasympathetic) increases |
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Term
| What are the effects of the ANS on salivary glands? |
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Definition
| Alpha-1 (sympathetic) causes thick/viscous secretions, M3 (parasympathetic) causes watery secretions |
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Term
| What is the pharmocological importance of the dominance of parasympathetics in GI tract innervation? |
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Definition
| Many drugs have anti-cholinergic effects, leading to dry mouth, nausea, vomiting, and constipation |
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Term
| What type of innervation relaxes or contracts the detrusor muscle in the bladder? |
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Definition
| Beta-2 (sympathetic) relaxes, M3 (parasympathetic) contracts |
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Term
| What type of innervation relaxes or contracts the trigone and sphincter of the bladder? |
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Definition
| Alpha-1 (sympathetic) contracts, M2 and M3 (parasympathetic) relaxes |
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Term
| What type of stimulation is characteristic of the filling phase of the bladder? |
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Definition
| Detrusor relaxes (beta-2), trigone and sphincter contract (alpha-1), filling is mediated by sympathetics |
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Term
| What type of stimulation is characteristic of the emptying phase of the bladder? |
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Definition
| Detrusor contracts (M3), trigone and sphincter relax (M2 and M3), emptying is mediated byparasympathetics |
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Term
| What stimulates renin secretion? |
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Definition
| Increase in renal sympathetic nerve outflow via Beta-1 adrenergic receptors. Alpha-1 receptors decrease secretion |
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Term
| What mediates male ejaculation? |
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Definition
| Sympathetic effects via alpha-1 receptors |
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Term
| What mediates male erection? |
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Definition
| Parasympathetic effects via M3 receptors initiating smooth muscle contraction and M3 mediated release of NO and vasodilation |
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Term
| Non-pregnant relaxation of the uterus is mediated by what? |
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Definition
| Beta-2 adrenergic receptors |
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Term
| What mediates relaxation of the uterus in pregnant women? |
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Definition
| Alpha-1 adrenergic receptors, Beta-2 mediates contractions |
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Term
| What causes myasthenia gravis? |
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Definition
| Loss of Ach receptors at the neuromuscular junction |
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