ANS Flashcards
General vs special
General
- In spinal and cranial regions
Specific
- Only in cranial regions
Somatic vs visceral
Somatic
- Innervate structures derived from somatopleure
Visceral
- Innervate structures derived from splachnopleure
Afferent vs Efferent
Afferent
- Input to CNS
Efferent
- Output from CNS
Autonomic efferent fibers innervate __________, _________ and _________; these fibers can be called _______________
Cardiac muscle, smooth muscles and secretory cells (in mucosa, dermis & glands)
General Visceral Efferents (GVE)
Somatic (and branchiomotor) motor fibers innervate _________ that is derived from ___________ and ___________; these fibers can be called ____________
striated muscle; somites and head mesoderm
General Somatic Efferents (GSE)
In ANS, the preganglionic neuron cell body _______ the CNS, with its axon synapsing on a ganglion __________ of the CNS.
Inside; outside
Somatomotor vs brachiomotor
Somatomotor
- GSE
- Innervate: Striated muscles
- Develop from myotomes or dorsal portions of the cranial paraxial mesoderm
Brachiomotor
- GVE
- Innervate: Striated muscles
- Develop from cranial paraxial mesoderm that has migrated into the pharayngeal arches
Somatomotor and Brachiomotor vs Visceral motor
Somatomotor and Brachiomotor
- 1 neuron from CNS to target
- Transmitter: Acetylcholine
- Fibers are highly myelinated
Visceral Motor
- 2 neurons (preganglionic and postganlionic)
- Transmitter: 1st is acetylcholine; 2nd is norepinephrine
- Preganglionic fibers are myelinated; postganglionic fibers are unmyelinated
NOTE: Postganglionic sympathetic fibers that innervate sweat glands ONLY secrete acetylcholine
Visceral Motor
- Innervate: Smooth muscle, cardiac muscle and secretory cells
- These target tissues devel from splanchnopleure mesoderm, neural crest, and dermal mesenchyme
Which organ in the sympathetic nervous system acts as a ganglia?
The adrenal glands sit on top of the kidneys. The adrenal medulla acts as a sympathetic ganglia with neuron like cells in it. These cells receive synapses and when activated they release norepinephrine into the bloodstream
___________ is referred to as the Cranio-Sacral “outflow”.
Parasympathetic nervous system
___________ is referred to as the Thoraco-Lumbar “outflow”.
Sympathetic nervous system
Where are central neurons for the parasympathetic nervous system located?
- brainstem (CN III, VII, IX, X) and
- sacral spinal cord (S2-4)
Where are central neurons for the sympathetic nervous system located?
Sympathetic central neurons are found only in the thoracic and lumbar spinal cord between T1 and L2.
Preganglionic sympathetic neurons are located in the _____________ in the lateral horn of the spinal cord, from T1- L2.
Intermediolateral cell column
Where do the postganglionic motor neurons of the parasympathetic nervous system synapse?
- Parasympathetic ganglia of the head
- Ciliary (Cranial nerve III)
- Submandibular (Cranial nerve VII)
- Pterygopalatine (Cranial nerve VII)
- Otic (Cranial nerve IX)
- In or near the wall of an organ innervated by the Vagus (Cranial nerve X) or Sacral nerves (S2, S3, S4)
Where do the postganglionic motor neurons of the sympathetic nervous system synapse?
-
Paravertebral ganglia of the sympathetic chain (these run on either side of the vertebral bodies)
- Cervical ganglia
- Thoracic ganglia
- Rostral lumbar ganglia
- Caudal lumbar ganglia and sacral ganglia
- Prevertebral ganglia (celiac ganglion, aorticorenal ganglion, superior mesenteric ganglion, inferior mesenteric ganglion)
- Chromaffin cells of adrenal medulla
Examples of structures/ functions that receive both sympathetic and parasympathetic input
Cardiac function
Pupillary reflexes
Cerebral vascular resistance
Which structures receive on sympathetic innervation?
- most arterial smooth muscle
- effectors in the skin such as arrector pili mm. and glands
- chromaffin cells in adrenal medulla.
Which structures receive only parasympathetic innervation?
- Ciliary body which helps change lens shape
- Lacrimal gland
- Salivary glands
Cerebral control of visceral motor activity is mediated through descending projections of the _________, especially by those of the ____________ nucleus
hypothalamus, paraventricular
Paraventricular nucleus of the hypothalamus
- A group of neurons that can be activated by physiological changes including stress.
- The PVN receives afferent inputs from many brain regions and different parts of the body, by hormonal control.
Where do the neurons in the paraventricular nucleus project?
- Hypothalamic-pituitary-adrenal (HPA)-axis
- The parasympathetic and sympathetic visceral motor nuclei of the brainstem and spinal cord.
Sympathetic trunk ganglia also known as______________
(a.k.a. sympathetic chain ganglia; paravertebral ganglia)
Prevertebral ganglia also known as___________
(a.k.a. preaortic ganglia)
The __________________projects to the preganglionic sympathetic visceral motor neurons in the intermediolateral cell column.
hypothalamospinal tract
Hypothamospinal tract
- Connects the hypothalamus to the ciliospinal center of the intermediolateral cell column in the spinal cord (T1 to L2).
- Lesions of the hypothalamospinal tract cause ipsilateral Horner’s syndrome.
Prevertebral ganglia
- Sympathetic ganglia which lie between the paravertebral ganglia and the target organ.
- Some of the targets present in the pelvic viscera include the enteric nervous system, as well as the renal system, bladder, and any other organs present in the abdomen.
The ganglion cells project postganglionic fibers through gray rami communicans to spinal nerves for distribution to ___________ and ____________.
blood vessels and dermis
Paravertebral sympathetic ganglia are derived from ______________
embryonic neural crest cells