Autonomic Nervous System Flashcards
Sympathetic Response
“fight or flight”
Emergency response, exercise, excitement
Parasympathetic Response
“Rest and Digest”
Regeneration of tissue, absorption of nutrients, energy diverted to digestive, reproductive, urinary, and immune systems
Somatic Function
Consciously controlled
Somatosensory Function
Sensory info travels from tissues to the CNS
-Muscles, joints, skin, special senses.
Somatamotor Function
Motor information traveling from the CNS to the skeletal muscles
Voluntary control from cerebrum
Involuntary movement and reflexes from brainstem and spinal chord.
Autonomic function
Processes which are regulated without conscious intent
Responds to visceral (organ) sensory input
Signals from CNS to heart, smooth muscle, glands
Maintains homeostasis
Hypothalamus
ANS control center
-Sympathetic and parasympathetic responses
-Influenced by frontal cortex and limbic system
Brainstem
Controls visceral reflexes
-Blood pressure regulation
-Direction of blood flow
-Cardiac activity
Spinal cord
-Controls two important visceral reflexes
-Urination and defecation
ANS Ganglia
- Collection of neuronal bodies found in the peripheral nervous system (synapses)
Posterior root ganglion
Cell bodies of unipolar sensory neurons
Sympathetic/Parasympathetic ganglia
Synapsing of preganglionic and postganglionic neurons
Parasympathetic division of the cranial nerves
“Craniosacral division”
-Originates at cranial nerves III, VII, IX, X and sacral nerves 2, 3, 4
-Long preganglionic neurons
-Synapse with short postganglionic fibers
-Ganglions found close to organs
Terminal Ganglia
-Parasympathetic ganglia
-Close to organ effector
Intramural Ganglia
-Parasympathetic ganglia
-Embedded into organ wall
Sympathetic division of cranial nerves
“Thoracolumbar”
-Originates in lateral horn of spinal segment t1 to L2
-Short preganglionic neurons
-Synapses with long postganglionic neurons
-Ganglia found close to spinal column
Sympathetic chain ganglia
On either side of the spinal column
Essentially operate as a relay station for the SNS
-Myelinated presynaptic neurons originate in lateral horns of spinal cord
Three options for synapsing:
1. Synapse in ganglion with postsynaptic neuron
2. Axon passes through ganglion and continues as part of splanchnic nerve
3. Axon ascends/descends in chain to synapse at higher or lower levels and continues as part of that spinal nerve
White Rami
Myelinated preganglionic sympathetic axons from nerve to ganglion
-“Exit ramp” from nerve; “entrance ramp” to ganglion
Gray Rami
Unmyelinated postganglionic sympathetic axons from ganglion to spinal nerve
Sympathetic Spinal Nerve Pathway
Preganglionic myelinated axons synapse in ganglion with unmyelinated postganglionic neuron
Postganglionic axons returns to spinal nerve
* Targets integumentary
structures
Postganglionic Sympathetic Nerve Pathway
Myelinated preganglionic axons synapse with unmyelinated postganglionic neurons in ganglion or ascend/descend chain to synapse with postganglionic neuron
* Targets head, neck, thoracic viscera
Cardiac nerve innervates heart
Splanchnic Nerve Pathway
Postganglionic axon passes through ganglion without synapsing
* Continues as part of splanchnic nerve
Greater splanchnic nerve
Lesser splanchnic nerve
Least (lowest) splanchnic nerve
* Targets abdominal and
pelvic viscera
Adrenal Medulla Pathway
Preganglionic axon passes through ganglion to lesser splanchnic nerve
* Targets adrenal glands
Stimulates release of adrenaline from adrenal glands
Maintains fight or flight response
Acetylcholine
Neurotransmitter of parasympathetic division
Cholinergic neurons
All ANS preganglionic neurons
All parasympathetic postganglionic neurons
Target cells have cholinergic receptors