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28 Cards in this Set
- Front
- Back
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What organs does the sympathetic nervous system innervate?
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-Single Innervation Target organs:
sweat glands peripheral blood vessels hair follicles brown adipose tissue adrenal medulla kidney -Dual Innervation Traget Organs: eye salivary gland lung heart ENS pancreas liver bladder reproductive organs BV of external genitalia |
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What is the structure of the Somatic Motor System?
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1.CNS command= cell body in the brain and spinal cord and the axon synapses directly on skeletal muscle
2. lower motor neuron 3.NMJ; excitation/contraction coupling 4.skeletal muscle contraction 5. movement |
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What are the two division of the Autonomic Nervous System?
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1. Sympathetic Nervous System
2. Parasympathetic Nervous System 3. ENS |
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What is the structure of the autonomic motor system?
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1.CNS command reflex to periphery
2.tonic control 3. preganglionic fiber 4. ganglia/post-ganglionic fiber 5. organ 6. response (+/-) -two neurons for every pathway (preganglionic and postganglionic) -preganglionic cell body in CNS and synapse on cell body of postganglionic neurons in one of autonomic ganglia |
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Describe the innervation of the sympathetic nervous system
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-short PREganglionics
-long POSTganglionics -preganglionic neurons originate in thoracic and lumbar segments of spinal cord (T1-L3) |
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What organ is a modified part of the sympathetic nervous system? How does it work?
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- Adrenal Medulla
- modified sympathetic ganglion that does not give rise to postganglionic fibers -stimulation of preganglionic fiber prompts secretion of hormones into blood -20% of hormone release= Norepinephrine -80% of hormone release = epinephrine |
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Describe the innervation os the parasympathetic nervous system:
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- long PREganglionics
-short POSTganglionics - preganglionic neurons originate in nuclei of brain stem and sacral segments (S2-S4) -craniosacral division |
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What type of receptors does the sympathetic system have for neurotransmitters?
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- for preganglionic neurotransmitter= NICOTINIC
- for postganglionic neurotransmitter = a1, a2, B1, B2 |
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What type of receptors does the parasympathetic system have for neurotransmitters?
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- for preganglionic neurotransmitters= NICOTINIC
- for postganglionic neurotransmitters = MUSCARINIC |
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What are the two main neurotransmitters of the sympathetic and parasympathetic nervous systems?
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1. Acetylcholine (ACh)
-nerves that use ACh are called CHOLINERGIC nerves -all sympathetic and parasympathetic preganglionic nerves release ACh -all PARAsympathetics postganglionic nerves release ACh - Sympathetic postganglionic nerves innervating the sweat glands in the skin and some skeletal muscle blood vessels release Ach 2. Norepinephrine -nerves that use NE= ADRENERGIC - most sympathetic postganglionic nerves release NE -adrenal medulla releases some NE into blood |
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What is the major hormone of the sympathetic nervous system?
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-Epinephrine
-released from the adrenal medulla after activation of the sympathetic nervous system |
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What type of neuron is the adrenal medulla classified as?
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- modified postganglionic neuron
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How is acetylcholine synthesized? Where is it stored? When is it released?
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- synthesized from AcCoA and choline by choline acetyl transferase (Chat)
-stored in vesicles -released when AP increases Ca+2 entry into the nerve endings -binds to receptor -broken down in the synaptic cleft by the enzyme ACETYLCHOLINESTERASE |
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How is NE synthesized?
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- tyrosine enters nerve terminal --> converted to DOPA -->DOPA converted to Dopamine -->Dopamine converted to NE
-NE stored in vesicles complexed with ATP -Release when AP increases Ca+2 entry into the cell |
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How does NE act presynaptically? postsynaptically?
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-Presynpatically= uptaken by the active pump mechanism UPTAKE 1
after uptake into the presynaptic neuron, NE is metabolized by the enzyme MAO (monoamine oxidase) -POSTsynaptically (target cells)= UPTAKE 2 pump brings it into the cell then it is metabolized by the enzyme COMT (catechol-o-methyltransferase) |
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Which uptake receptor for NE is affected by cocaine and tricyclic antidepressants?
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- UPTAKE 1
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Where can nicotinic receptors be found?
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- on motor end plate in all autonomic ganglia and on chromaffin cells of the adrenal medulla
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What is tonic activity?
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- active under "resting" conditions
- ability to increase or decrease activity -both SNS and PNS are tonically active to most organs they innervate and their ratio determines the net effect on that organ |
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What is reflex activity?
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-response to a change in environment; may not require cortical processing
-many basic autonomic reflexes can be modulated by other inputs to the CNS or by higher brain centers |
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What effects does the SNS have in the fight/flight response?
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-Dilate pupils (MYDRIASIS
-increase secretion of THICK, VISCOUS saliva - decrease intestinal motility -stimulate hepatic glycogenolysis plus inhibit insulin release from pancreas to raise blood glucose - increase HR and cardiac contractility - dilation of bronchial smooth muscle - sweating (sympathetic cholinergic) |
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What effects does the PNS have during rest/digest?
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- constricts pupils (MIOSIS)
- increase secretion of WATERY saliva - enhance emptying of GI and urinary tracts - stimulate insulin release-->enhanced blood glucose storage as fat and glycogen - slow heart rate - constrict airways - vasodilate resistance vessels of the coronary circulation |
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How does the autonomic system control bladder function?
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- sympathetic control (B2 and a1 receptors) predominates during filling-->relaxtion of the detrusor muscle and contraction of the internal sphincter
- During micturition= Parasympathetic control (Muscarinic receptors) predominates -->contraction of the detrusor muscle and relaxation of the internal sphincter |
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What are the exceptions to the dual reciprocal innervation of the SNS and the PNS?
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- most arterioles and veins receive only sympathetic nerve fibers
- most sweat glands are innervated only by sympathetic nerve fibers -salivary glands innervated by both but not antagonistic because both cause secretion |
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What is the role of the hypothalamus?
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-integrates autonomic, somatic, and endocrine responses that automatically accompany various emotional and behavioral states
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What region within the brainstem is directly responsible for autonomic output?
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Medulla
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What autonomic reflexes are integrated at the spinal cord?
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urination, defecation, and erection
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How do autonomic agonists work?
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- bind to same receptor as neurotransmitter
-elicit an effect that mimics that of neurotransmitter |
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How do antagonists work?
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- bind with receptor
- block neurotransmitters response |
