ANS - The Autonomic Nervous System Compare/Contrast Somatic...

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The Autonomic Nervous System The Autonomic Nervous System
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Sensory neurons  pick up/carry information from skin (pain, touch, temp.), muscle proprioception,  special senses -  conscious perception (usually Motor neurons  carry  excitatory signal    contraction of skeletal muscles  (no signal, loss of  muscle tone to  denervation atrophy/paralysis ) No active inhibition; just ‘lack of excitement’ Is a  voluntary NS  (most under  conscious control   except reflexes, hearing) Autonomic NS (ANS ) = Visceral Motor NS; ‘self governed’ Input from  autonomic sensory neurons   Ex. Chemoreceptors to monitor blood CO 2,  Stretch receptors in walls of visceral organs,  blood vessels. Osmoreceptors to √  blood osmolarity Sensation  not usually consciously perceived  (except damage e.g., angina) Autonomic motor neurons  direct  smooth/cardiac muscle, glands Can  increase or decrease action in target organ Typically  modulating effect : organ often functions w/o ANS innervation (e.g., heart will  beat - faster - if ANS connections severed); see  denervation hypersensitivity (exaggerated response) Involuntary NS  - not under conscious control ( visceral reflexes ) Enteric NS  - in GI tract; reflex within organ (no inclusion of CNS)
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Give an example of an ANS reflex 3. Integration in gray matter of medulla (sum IPSPs, EPSPs) 4. Efferent response out via Cranial Nerve X (Vagus) 1. Direction to cardiac muscle heart rate ( BP homeostasis) Note 2 nd ganglion in organ Medulla CNS connection Separate ganglion (2 nd synapse); here, near target organ Like somatic reflexes, unconscious/ involuntary control, stereotyped Slower than somatic reflexes (< myelin) Objective is typically homeostasis (protection, but different way) 1. Stretch receptor ( baroreceptor ) in carotid artery picks up pressure 2. Afferent pathway via Cranial N IX (Glossopharyngeal N) to medulla ( CNS ) IN
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Which of the following is not true about  Which of the following is not true about  autonomic reflexes? autonomic reflexes? A. They typically result in homeostasis B. Severing of ANS motor neurons results in denervation  atrophy of the muscles that were innervated C. The responses are similar to somatic reflexes in that  they are involuntary and sterotyped D. ANS receptors measure features such as pressure,  osmolarity and blood gas levels E. All of these are true about ANS reflexes
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MN: Cell body in CNS; one axon all the way to the effector (no ganglion in efferent pathway); whole axon is myelinated (faster) Only 1 NT (ACh); always excitatory 2 neurons: Preganglionic: Cell body in CNS; one axon to 2 nd ganglion ; synapse; second ( postganglionic ) neuron effector
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This note was uploaded on 07/29/2009 for the course BIO 201IN taught by Professor Brooks during the Spring '09 term at University of Arizona- Tucson.

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ANS - The Autonomic Nervous System Compare/Contrast Somatic...

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