Chapters 18 19 1 Describe the components of the peripheral nervous system 2 Explain the difference between preganglionic neurons and ganglionic neurons Stimulation of Sympathetic Preganglionic Neurons Releases ACh acetylcholine at synapses with ganglionic neurons Excitatory always effect on ganglionic neurons Ganglionic Neurons Release neurotransmitters mostly NE but some release Ach at specific target organs Axon terminals Form branching networks of telodendria instead of synaptic terminals Telodendria form sympathetic varicosities Resemble string of pearls swollen segment packed with neurotransmitter vesicles that pass along or near surface of effector cells Effectors do not have specialized postsynaptic membranes just membrane receptors on surfaces of the target cells Release NE at most varicosities Called adrenergic neuron Most NE is reabsorbed or inactivated by the enzyme monoamine oxidase MAO Some ganglionic neurons release ACh instead Are located in body wall skin brain and skeletal muscles Called cholinergic neurons 3 Explain the function of the sympathetic and parasympathetic divisions of the ANS Sympathetic division Increases alertness metabolic rate and muscular abilities Kicks in only during exertion stress or emergency Fight or flight Parasympathetic division Reduces metabolic rate and promotes digestion In control during resting conditions Rest and digest Sympathetic and Parasympathetic Division roles 1 Most often these two divisions have opposing effects If the sympathetic division causes excitation the parasympathetic causes inhibition 2 The two divisions may also work independently Only one division innervates some structures 3 The two divisions may work together with each controlling one stage of a complex process Male sexual physiology erection parasymphathetic while ejaculation sympathetic 4 Explain the difference in the anatomy of the sympathetic and parasympathetic divisions of the ANS Parasympathetic Division Preganglionic fibers originate in brain stem and sacral segments of spinal cord craniosacral division Synapse in ganglia close to or within target organs Preganglionic fibers are long Postganglionic fibers are short Parasympathetic division stimulates visceral activity Conserves energy and promotes sedentary activities Organization and Anatomy of the Sympathetic Division Ventral roots of spinal segments T1 L2 contain sympathetic preganglionic fibers Give rise to myelinated white ramus Carry myelinated preganglionic fibers into sympathetic chain ganglion May synapse at collateral ganglia or in adrenal medullae Sympathetic Division Preganglionic fibers thoracic and superior lumbar thoracolumbar division synapse in ganglia near spinal cord Preganglionic fibers are short Postganglionic fibers are long except at adrenal medullae Prepares body for crisis producing a fight or flight response i Stimulates tissue metabolism ii Increases alertness Preganglionic neurons located between segments T1 and L2 of spinal cord Ganglionic neurons in ganglia near vertebral column Cell bodies of preganglionic neurons in lateral gray horns of spinal cord Axons enter ventral roots of segments Organization and Anatomy of the Sympathetic Division Ventral roots of spinal segments T1 L2 contain sympathetic preganglionic fibers ganglion Give rise to myelinated white ramus Carry myelinated preganglionic fibers into sympathetic chain May synapse at collateral ganglia or in adrenal medullae 5 Explain what happens to the body when the sympathetic division is active Seven Responses to Increased Sympathetic Activity Heightened mental alertness Increased metabolic rate Energy reserves activated Increased respiratory rate and respiratory passageways dilate Increased heart rate and blood pressure Sweat glands activated Reduced digestive and urinary functions 6 Explain what happens to the body when the parasympathetic division is active Five Responses to Increased Parasympathetic Activity Decreased metabolic rate Decreased heart rate and blood pressure Increased secretion by salivary and digestive glands Increased motility and blood flow in digestive tract Urination and defecation stimulation 7 Describe where the ganglionic neurons of the sympathetic division are located a What is the sympathetic chain ganglia What is its function Ganglionic Neurons b Axon terminals i Form branching networks of telodendria instead of synaptic terminals ii Telodendria form sympathetic varicosities 1 Resemble string of pearls swollen segment packed with neurotransmitter vesicles that pass along or near surface of effector cells 2 Effectors do not have specialized postsynaptic membranes just membrane receptors on surfaces of the target cells c Axon terminals i Release NE at most varicosities 1 Called adrenergic neuron Most NE is reabsorbed or inactivated by the enzyme monoamine oxidase MAO ii Some ganglionic neurons release ACh instead 1 Are located in body wall skin brain and skeletal muscles 2 Called cholinergic neurons Found in three locations 1 Sympathetic chain ganglia 2 Collateral ganglia 3 Suprarenal medullae Sympathetic Chain Ganglia Preganglionic neurons located in T1 L2 Are on both sides of vertebral column Control effectors In body wall Inside thoracic cavity In head In limbs Preganglionic fibers One preganglionic fiber synapses on many ganglionic neurons Fibers interconnect sympathetic chain ganglia Each ganglion innervates particular body segment s Postganglionic fibers control visceral effectors In body wall head neck or limbs Postganglionic fibers innervate effectors Sweat glands of skin Smooth muscles in superficial blood vessels Postganglionic fibers innervating structures in thoracic cavity form bundles called sympathetic nerves Only spinal nerves T1 L2 have white myelinated rami Every spinal nerve has gray unmyelinated ramus that carries sympathetic postganglionic fibers for distribution in body wall Collateral Ganglia Are anterior to vertebral bodies Contain ganglionic neurons that innervate tissues and organs in abdominopelvic cavity Receive sympathetic innervation via sympathetic preganglionic fibers as Splanchnic nerves does not form synapse in sympathetic chain Postganglionic fibers leave collateral ganglia Extend throughout abdominopelvic cavity Innervate variety of visceral tissues and organs Release of stored energy reserves Reduction of blood flow and energy by organs not vital to short term survival ex Digestive tract Adrenal Medullae Suprarenal Medullae Very short axons When
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