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9 Cards in this Set
- Front
- Back
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What is a reflex?
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A reflex is a:
Fast, involuntary sequence of actions that occurs in response to a particular stimulus. |
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Reflexes can be both a spinal reflex and a cranial reflex.
True or False? |
True
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Reflex Arc
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*Basic functional unit of nervous system and simplest portion capable of receiving a stimulus and producing a response
*Automatic response to a stimulus that occurs without conscious thought. Homeostatic. |
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Reflex Arc
Components |
1) Sensory receptors transmitted to 2) sensory neuron to 3) Interneurons to 4) motor neurons to 5) motor neurons to 6) effector organ which responds with a reflex.
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Variety of Reflexes
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+Some integrated within spinal cord; some within brain
+Some involve excitatory neurons ; some involve inhibitory neurons . +Higher brain centers can influence, suppress, or exaggerate reflex responses |
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Stretch Reflex
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+Muscles contract in response to a stretching force applied to them. Unique because no interneuron.
+Muscle spindle: specialized muscle cells that respond to stretch. +Sensory neurons innervate the noncontractile centers of the muscle spindle cells. +These sensory neurons synapse with motor neurons of the spinal cord which in turn innervate the muscle in which the muscle spindle is embedded. |
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Golgi Tendon Reflex
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+Prevents contracting muscles from applying excessive tension to tendons
+Golgi tendon organ. +Nerve endings that have at their ends numerous terminal branches . +Prevent damage to tendons that could be caused by excessive tension +Produces sudden relaxation of the muscles Example: weight lifter suddenly drops heavy weight. |
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Withdrawal Reflex
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Function is to remove a body limb or other part from a painful stimulus.
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Relationship of brain and spinal cord reflexes
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+Sensory information goes to brain; e.g., pain.
+Descending tracts from brain carry info to reflexes. +Neurotransmitters produce either EPSPs or IPSPs modifying the reflex. |
