Autonomic Nervous System Flashcards
Autonomic Nervous System (ANS)
Regulation of Function ~
paired endocrine (slow / long-lasting) and ANS (rapid / short-acting)
Autonomic Nervous System
Sensory System ~
GVA from only the core, NOT the periphery
ANS Sensory System Receptors:
nocireceptors (pain), mechanoreceptors (fullness), other specialized receptors
ANS Sensory System Cell Bodies:
pseudounipolar neurons in DRG of T1-L2 (SNS) + S2-S4 (PaNS) and CN IX / X nuclei
Autonomic Nervous System
Motor System ~
rapid single/multi-synaptic effector motor system with sensory input @ spinal cord, brainstem and cerebral hemisphere
ANS Motor System Efferent (GVE):
2-neuron system; contrast w/somatic (GSE) 1-neuron
ANS Motor System Target:
smooth muscle (BP / peristalsis), cardiac muscle (HR, Force) and glands (secretion)
ANS Motor System Core + Periphery:
parasympathetics only core; SNS both core & periphery
Input to ANS =
Hypothalamus
ANS 1° Neuron has cell body in
hypothalamus —> axon via descending pathways to:
a) PaNS: CN III, VII, IX and X nuclei in brainstem/medulla + S2-S4 lateral horn
b) SNS: intermediolateral horn of T1-L2
Sympathetic (Thoracolumbar T1-L2)
1° Neuron (descending pathway) —>
2° Neuron (Interomedolateral Horn) —> Ventral Root —> White Rami —> Sym Chain
- Synapse: at same level —> gray rami —> peripheral nerve
- Rise/Drop: at different level —> gray rami —> peripheral nerve at different level
- Leaves w/Out Synapse: synapses in prevertebral ganglion (splanchnic); pelvic + abdominal viscera
Sympathetic (Thoracolumbar T1-L2)
Preganglionic —> Postganglionic
Preganglionic —> AcH —> Postganglionic —> NorEpi
- Exception: sweat glands + erector pili muscle receive AcH
- Note: adrenal medulla chromaffin cells get direct
preganglionic with AcH
Parasympathetic (Craniosacral)
CN III:
Edinger-Westphal (Midbrain) —> Ciliary Ganglion
—> Constrict Pupil
Parasympathetic (Craniosacral)
CN VII:
Superior Salivatory (↑Medulla) —> PP/SMD —> Lacrimal/Salivary
Parasympathetic (Craniosacral)
CN IX:
Inferior Salivatory (↑Medulla) —> Otic —> Parotid Gland
Parasympathetic (Craniosacral)
CN X:
Nucleus Ambiguus/Dorsal Motor Nuc of Vagus (mid-Medulla) —> Visceral —> bronchioconstriction, ↓HR, dilate abdominal arteries
Parasympathetic (Craniosacral)
S2-S4:
Lateral Horn S2-S4 —> syn peripheral —> desc colon/pelvic viscera
Parasympathetic (Craniosacral)
Preganglionic —> Postganglionic
Preganglionic —> AcH —> postganglionic —> AcH
Enteric System Organization:
receives SNS (tertiary neuron w/NorEpi) and PaNS (AcH) + intrinsic enteric nervous system = Myenteric / Submucosal Plexi
Myenteric (Auerbach) Plexus =
between circular and longitudinal muscle layer; regulates smooth muscle / motility
Submucosal (Meissner) Plexus =
between muscularis mucosa and circular smooth muscle; regulates glandular secretions
Enteric System can operate independently of
ANS; final common pathway is via enteric neurons with AcH as nueroTx
Parasympathetics
Eye
Targets/Response
Pupil = Constricts
radial muscle = contracts
ciliary muscle = contracts
near vision
Sympathetics
Eye
Targets/Response
Pupil = Dilates
radial muscle = relaxes
ciliary muscle = relaxes
far vision
Parasympathetics
Gland
Targets/Response
Lacrimal = ↑ Salivary = watery Parotid = watery Sweat = n/a
Sympathetics
Gland
Targets/Response
Lacrimal = n/a Salivary = thick Parotid = thick Sweat = ↑