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23 Cards in this Set
- Front
- Back
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What are the Central and Peripheral divisions of the ANS?
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Central:
-integrating autonomic centers in the brain: limbic system, HT, brain stem -efferent preganglionic; brain and spinal cord Peripheral: -efferent preganglionic -efferent postganglionic neurons; plexuses -efferent postganglionic fibers |
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Where are the Pre-ganglionic and Post-ganglionic neurons in the SNS and PSNS found?
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Pre-ganglionic:
Sympathetic - Thoracolumbar division; lateral horns of T1-T12 and L1-L2 (L3) Parasympathetic - craniosacral division; brain stem nuclei of CN III, VII, IX, X and lateral horns of S2-S4 Post-ganglionic: Sympathetic: -Paravertebral ganglia - from skull base to coccyx, vertical rows on vertebral column -Prevertebral ganglia - anterior to vertebral column, close to large abdominal arteries Parasympathetic: -Intramural/terminal ganglia - located within or close to walls of visceral organs |
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What do the different levels do in the Sympathetic Trunk Ganglia?
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3 Cervical:
-located in neck -Superior: supplies head and heart -Middle and Inferior - heart 11-12 thoracic: -most of the preganglionic sympathetic axons -supply thoracic viscera, sweat glands, blood vessels 4-5 lumbar 4-5 sacral 1 coccygeal |
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What are characteristics of the synapsing of preganglionic neurons for the sympathetic ganglia?
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Diverging pathways - 1 preganglionic neuron through collaterals synapses with many postganglionic neurons --> generalization of sympathetic response
White ramus - myelinated preganglionic axons that connect anterior ramus of spinal nerve with sympathetic ganglia gray ramus - unmyelinated postganglionic axons that connect ganglia to spinal nerves |
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What are the major autonomic plexuses?
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Cardiac - supplies the heart
Pulmonary - bronchial tree Celiac - the liver, galbladder, stomach, pancreas, spleen, AM, kidneys, AM, testes and ovaries Superior mesenteric - small and large intestines Inferior mesenteric - large intestine Hypogastric - pelvic viscera Renal - renal arteries, ureters |
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What are Splanchnic nerves?
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formed from preganglionic sympathetic fibers, DONT synapse
terminate in prevertebral ganglia and plexuses |
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What are some features of the organization of the PSNS?
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minimal diverging pathways --> localized parasympathetic response
CN III, VII, IX: --> Terminal Ganglia (ciliary, pterygopalatine, submandibular, otic) --> short post fibers --> lacrimal and salivary glands, mucous membranes, eye, visceral organs CN X, S2-S4 (Pelvic splanchnic nerves) --> intramural (terminal) ganglia --> lacrimal and salivary glands, mucous membranes, eye, visceral organs |
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What do each of the nerves in the PSNS do?
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CN III (Oculomotor):
-preganglionic --> ciliary ganglia -postganglionic --> smooth muscles of the eyeball CN VII (facial): -preganglionic1 --> pterygopalatine ganglia -postganglionic1 --> nasal mucosa, palate, pharynx, lacrimal glands -preganglionic2 --> submandibular gangia -postganglionic2 --> submandibular and sublingual salivary glands CN IX (Glossopharyngeal): -preganglionic --> otic ganglia -postganglionic --> parotid salivary glands CN X (Vagus): -preganglionic --> terminal ganglia -postganglionic --> heart, airways, liver, galbladder, stomach, pancreas, small intestine, part of large intestine *80 % OF PSNS OUTFLOW* Pelvic Splanchnic Nerves: -Preganglionic --> S2-S4 -Postganglionic --> intramural parasympathetic ganglia -innervate smooth muscles and galnds of colon, uterus, urinary bladder, and reproductive organs |
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What are the Autonomic centers in the brain?
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Higher brain levels - limbic system, frontal lobe
Hypothalamus: -head ganglion of ANS -axons for SNS and PSNS relay to rest of body through reticular formation -Posterior and Lateral nuclei = SNS -Anterior and Medial nuclei = PSNS -Does NOT have direct effect on vegetative organs: ANS in HT are part of more complex (emotions etc) Brain stem centers - respiratory, micturation, vasopressor, etc |
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What is the relationship between the Adrenal Medulla and the SNS?
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-derived from same precursor (neural crest)
-similar to postganglionic SNS but do not have axons and release secretory products into blood -innervated by preganglionic SNS neurons (release Ach) -adrenaline (epinephrine) = 80 % secretion -noradrenaline and dopamine = 20 % |
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What are Neurotransmitters and some ANS neurotransmitters?
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Neurotransmitters:
-chemical messengers synthesized by neurons that interact with integral membrane proteins on a postsynaptic cell -SHORT term action ANS Neurotransmitters: Acetylcholine: -synthesized in cholinergic nerve fibers by enzyme choline acetyltransferase (CAT) from choline, acetyl CoA in presence of ATP and glucose -stored in vesicles and released by exocytosis -removal from synaptic cleft and degradation by: diffusion, splitting into acetate and choline (hydrolysis) by acetylcholine-esterase (AChE), reuptake (active process of choline uptake is important) -ALL preganglionic parasympathetic and sympathetic, postganglionic parasympathetic, and postganglionic sympathetic to sweat glands Noradrenaline: -synthesized in adrenergic neurons of chromaffin cells of adrenal medulla -derived from AA tyrosine -stored in granules associated with ATP -released by exocytosis -removal from synaptic cleft and degradation: 85 % neuronal uptake --> storage or inactivation by monoamine oxidase (MAO); diffusion; 15 % extraneuronal uptake by liver, lungs and kidney and degradation by COMT -ALL postganglionic sympathetic (except sweat glands) NANC (Non-adrenergic, non-cholinergic): -Dopamine: interneurons in sympathetic ganglia -LHRH: some preganglionic neurons -ATP, VIP, NPY, GABA, 5HT |
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What are characteristics of adrenergic receptors?
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-based on sensitivity to natural catecholamines (CA) and synthetic CA - ISO & types of intracellular mediators
-Adr binds to beta receptors -NAdr binds to alpha receptors -activation of alpha1 and beta1 produces excitation, alpha2 and beta2 for inhibition |
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What are Nicotinic and Muscarinic receptors?
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-both come from Ach (cholinergic)
Muscarinic receptors: -come from muscarine (mushroom poison) -effectors innervated by postganglionic PSNS -sweat glands, some blood vessels, piloerector muscles innervated by cholinergic postganglionic SNS -CNS -causes depolarization or hyperpolarization Nicotinic: -NMJ -Autonomic ganglia: all postganglionic SNS and PSNS; adrenal medulla -CNS -causes depolarization |
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What are agonists and antagonists and examples?
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Agonists:
-full agonism (similar to hormone or neurotransmitter) -partial agonism ex. phenylephrine binds to alpha1 --> contraction of blood vessels in nasal mucosa --> decrease production of mucus --> decrease nasal congestion Antagonists: -full antagonism - no cellular response -partial antagonism ex. atropine: blocks muscarinic cholinoreceptors and prevents their activation by Ach --> dilation of pupil (eye examination) and relaxation of GI smooth muscle (treatment of intestinal hypermotility) propranolol: block Beta1 --> lower heart rate and BP; block Beta2 --> bronchoconstriction, hypoglycemia |
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What are the differences between the Somatic NS and the ANS?
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Somatic:
-voluntary control from cerebral cortex with contributions from BG, cerebellum, spinal cord, and brainstem -one-neuron pathway -all release Ach -effects skeletal muscle ANS: -involuntary control from hypothalamus, limbic system, brainstem and spinal cord; limited control from cerebral cortex -two-neuron pathway -Ach and NE -effects smooth muscle, cardiac muscle, and glands |
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What is autonomic tone?
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The basal level of sympathetic and/or parasympathetic activity:
ex. Basal cardiac rate (at rest) - determined by PSNS tone Basal level of constriction of blood vessels - SNS Basal level of contraction of GIT smooth muscles - PSNS -HT balances between sympathetic and parasympathetic activities (tone) Significance: allows balance between 2 divisions or one ex. increase parasympathetic --> lower HR, increase GIT motility decrease parasympathetic --> increase HR, decrease GIT motility Loss of tone: -Denervation --> loss of tone --> effects of lost innervation (ex. maximal vasodilation, GIT atony, increase HR) |
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What are ANS reflexes?
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-localized alterations of activity in isolated portions of SNS or PSNS
Definiton: -involuntary, "built in", automatic response to stimulus Types: -central: integrated in CNS -peripheral: peripheral ganglion of ANS -local: all elements of reflex arc are located within a particular organ -axon: conduct impulses back to organ where impulse was generated (ex. skin - release of substance P from collateral terminals --> vasodilation) Components of reflex arc: -receptors: interoreceptors -afferent pathway: autonomic and somatic -integration center: in spinal cord, brain stem, HT -efferent pathway: pre and post ganglionic autonomic neurons -effectors: smooth and cardiac muscles, glands |
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What is Mass discharge?
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-discharge as a complete unit
more characteristic for SNS than PSNS: -longer life span of NAdr -prolonged response of CA released from AM -alarm or stress response (fight or flight) to E stimulation (emergency, exercise, excitement, embarrassment) |
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What are some Parasympathetic responses?
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-rest and digest activities
SLUDD (stimulation of): -Salivation -Lacrimation -Urination -Digestion -Defecation 3 decreases: -HR -Airway diameter (bronchoconstriction) -pupil diameter (constriction) |
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What are some Sympathetic Responses?
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-fight or flight reaction
decrease of body functions that favor storage of energy: -vasoconstriction: kidney and GIT (decrease urine formation and digestion) -decrease GI motility increase functions that support physical activity and rapid production of energy: -Vasodilation: skeletal muscle, myocardium, liver, adipose tissue --> increase blood flow and functional activity (ie increase muscle strength) -increase rate of blood coagulation -increase HR and force of contraction --> increase BP -bronchodilation to improve pulmonary gas exchange -dilation of pupil and relaxation of ciliary muscle for better distant vision -increase mental activity |
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What is Horner's Syndrome?
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Loss of sympathetic innervation of one side of the face caused by:
-Injury -Inherited Mutation -Disease of the superior cervical ganglion Symptoms and signs: -Ptosis (drooping of upper eyelid) -Miosis (constriction of pupil) -Anhidrosis (lack of sweating) |
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What is Raynaud's Phenomenon?
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Causes:
-Emotonal Stress -Cold -Smoking -Increase in alpha receptors -hypotension -young women Pathology: Excessive sympathetic stimulation of arterial smooth muscles of digits --> vasoconstriction (decrease blood flow) --> whitening of digits --> cyanosis --> dilation of arterioles (red color) and necrosis of digits Treatments: -Ca channel blocker -Alpha receptor blocker |
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What is Autonomic Dysreflexia?
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exaggerated response that occur after spinal cord injury
Pathology: spinal cord injury at or above T6 --> interruption of supraspinal control of ANS --> mass stimulation of sympathetic neurons below injury level (triggered by sensory impulses from viscera) --> severe vasoconstriction (increase BP) --> activation of CV center in medulla --> increase in PSNS activity, decrease in SNS (lower HR) [vasodilation ABOVE injury level] Symptoms: -Pounding headache, flushed wark skin and profuse sweating above injury level -dry skin below injury level -seizures, strokes, heart attacks |
