Reflex Action and Reflex Arc Anatomy

Receptor = Specialized structure sensing changes inside or outside the body Afferent (sensory) neuron = Carries impulses from the receptors to the CNS Center = Location in the CNS, can be a collection of cell bodies like AHC Efferent (motor) neuron = Carries impulses from CNS to the effector organ

Somatic reflex arc = Involves one neuron in the efferent pathway Autonomic reflex arc = Involves two neurons with synapse at ganglia Preganglionic neuron = Cell bodies located in LHC for autonomic reflex arc Postganglionic neuron = Cell bodies located in ganglia for autonomic reflex arc

Sympathetic division = Controls fight or flight responses Parasympathetic division = Controls rest and digest responses Myelination type for Preganglionic neurons in autonomic reflex arc = Myelinated (Type B) Myelination type for Postganglionic neurons in autonomic reflex arc = Myelinated (Type A)

<p>Anterior horn cell (AHC) = Part of the center in somatic reflexes Lateral horn cell (LHC) = Part of the center in autonomic reflexes Effector organ = Structure that produces the response Division that controls involuntary body activities = Autonomic Nervous System</p> Signup and view all the answers

<p>Somatic reflex action = Classified based on voluntary muscle movements Autonomic reflex action = Classified based on involuntary physiological responses Types of divisions in Autonomic Nervous System based on function = [Sympathetic, Parasympathetic] Classification based on somatic and autonomic responses = [Somatic, Autonomic]</p> Signup and view all the answers

<p>Postganglionic fibers = Unmyelinated fibers that carry nerve impulses away from the autonomic ganglia to effector organs Autonomic ganglia = Collections of nerve cell bodies outside the CNS where preganglionic fibers relay with postganglionic fibers Sympathetic ganglia = Ganglia formed by lateral sympathetic chains, including cervical and thoracic ganglia Parasympathetic ganglia = Ganglia where only parasympathetic fibers relay to supply effector organs</p> Signup and view all the answers

<p>Sympathetic division = Originates from the thoracolumbar region of the spinal cord (T1-T12) Parasympathetic division = Originates from cranial nerves (3, 7, 9, 10) and the middle three sacral segments (S2-S4) Postganglionic fibers = Relay impulses to effector organs in both divisions of the ANS CNS structures = Includes gray matter, horn, nucleus, and ganglion in both the CNS and PNS</p> Signup and view all the answers

<p>Lateral ganglia = Lie on both sides of the vertebral column Collateral ganglia = Lie at the origin of major arteries from the abdominal aorta Terminal ganglia = Located very near or within the organ they supply Spinal cord segments = Includes thoracic segments for sympathetic ganglia and sacral segments for parasympathetic ganglia</p> Signup and view all the answers

<p>Stress response = Associated with sympathetic activity, catabolic processes, and mass discharge of impulses Rest and relaxation = Associated with parasympathetic activity, anabolic processes, and localized activation of parts separately Distributing center role = Compensates for limited origin of autonomic nervous system by relaying one preganglionic fiber with many postganglionic fibers Fiber activation ratio = One sympathetic pre-ganglionic fiber can activate 32 postganglionic fibers compared to 2 in parasympathetic activation</p> Signup and view all the answers

<p>Sympathetic chain relay = Relays only sympathetic preganglionic fibers in lateral sympathetic ganglia Mixed relay = Involves relaying both sympathetic and parasympathetic fibers in collateral ganglia Parasympathetic relay = Relays only parasympathetic preganglionic fibers in terminal ganglia Site proximity = Collateral ganglia lie midway between spinal cord and viscera while terminal ganglia are very near or within effector organs</p> Signup and view all the answers