Classifications of the PNS (Quiz 5) Flashcards
Are there nerves in the CNS?
no
more myelin = ___________ transduction
faster
define nerve
bundle of axons
What does somatic refer to?
-cells of the body
-somatic branch of the NS innervates the body wall
-includes skin, bone, blood, and skeletal muscle
Somatic branches develop from what?
ectoderm and mesoderm
What does visceral refer to?
-organs, guts, internal membranes/tubes
-tunica media, all organs and related smooth m.
What is viscera formed from?
endoderm
Is viscera voluntary or involuntary?
involuntary (unconsciously aware)
T/F: all spinal nerves are mixed nerves
true
A connective tissue sheath- the _____________ surrounds each nerve. Each bundle of nerve fibers is called a fasciculus and is surrounded by a layer of connective tissue called the _______________. Blood vessels are associated with each fascicle
epineurium, perineurium
Individual axons are surrounded by loose connective tissue called the….
endoneurium
What does it mean if a nerve is general?
-has pathways and receptors
-distributed throughout body
-no specific modality, threshold, or info transmitted
What does it mean if a nerve is special?
-receptors and related axons, and pathways are from specific structures
there are 3 types:
1) unique anatomical structures
2) different modalities and detection mechanisms than general nerves
3) developmentally special
What are the 3 classifications of the PNS?
1) general or special
2) somatic or visceral
3) afferent or efferent (direction)
What does afferent mean?
-going in
-info goes from PNS into CNS
-input goes to brainstem or spinal cord
-sensory info
What does efferent mean?
-going out
-info goes from CNS to PNS
-goes from CNS to target tissue
-motor info
Both efferent and afferent are used to describe direction of….
nerves (bundles of axons in PNS)
What is the function of GSA?
-all spinal nerves contain GSA
-general sensation on pain, temp, light touch, pressure, vibration, proprioception
-receptors are thermal, nociceptors and mechanoreceptors
-innervates skin
What is the function of GVA?
-input from visceral/internal organs, glands, or blood vessels
-often pain or reflex info
What is the function of GSE?
-info comes from large ventral horn neurons
-info goes to skeletal m. in body wall and extremities
-found all throughout spinal cord
What is another name for GSE?
LMNs
What is the function of GVE?
-preganglionic neurons that form the ANS
-sympathetic from T1-L4
-parasympathetic from S1-S4 and all CNs
-info goes out to smooth m. tubes or glands
What is the function of SVE?
-motor innervation to muscles of the pharyngeal arches/ brachial arches (this is developmentally special, info goes to voluntary striated muscles of the larynx and pharynx), muscles of mastication, and facial expression
-anything motor with swallowing, breathing, talking, etc
note: this is visceral bc its the start of GI tube, thats why its not somatic
What is the function of SVA?
-sensory fibers that develop in association with the GI tract
-carry olfaction and gustation info
-taste via CN VII and IX
