Peripheral Nerves Flashcards
Preganglionic Neuron
cell body in CNS
Postganglionic Neuron
cell body in ganglion
Mutlipolar neurons
CNS neurons- anterior horn motor neuron
Bipolar neurons
Retina
Statoacoustic Nerve Ganglion
-special senses
Unipolar neurons
posterior root ganglia
cranial nerve ganglia
Somatic Afferent:
- _____ sensibility from ____ (monitors external environment)
- -P___
- -T___
- -T___
- -C___P___
- —-awareness of limb position
- exteroceptive sensibility from skin
- pain
- touch
- temperature
- conscious proprioception
Somatic Efferent:
- allows for ____ with _____ environment
- -controls of ________
- interaction with external environment
- controls striated (voluntary) mm
Visceral Efferent:
- allows for ____ of _____ environment
- -autonomic efferent
- –2 ____ chain
- —______ neuron: cbo within CNS
- —______ neuron: cbo in autonomic ganglion
- contraction of _____ mm
- secretion of _____
- control of internal environment
- –2 neuron chains= preganglionic and postganglionic
- contracts smooth mm
- secrets glands
Visceral Afferent:
- _____ _____= monitors internal environment, e.g.
- -______afferent
- –heart rate
- –blood pressure
- –smooth mm contractility
- –bladder and bowel fullness
- visceral sensibility
- -autonomic afferent
Posterior Horn
sensory
enters spinal cord
Anterior Horn
motor
leaves spinal cord
Myelin:
- membrane of ___ cells
- covers up to ____ of axon
- _____ axon membrane and increases ______ velocity
- glial cells
- 1cm
- insulates membrane and increases conduction
Myelin producers:
- oligodendroglia cells (CNS)
- schwann cells (PNS)
True or False:
The thicker and longer the internodal distance on an axon the slower the signal travels.
FALSE= the faster it travels
Degeneration of Axon:
- crushed
- -myline degenerates
- -____break
- -____ and _____ ___ remains intact
- -______ enters from capillaries
- -axon breaks up
- -endoneurium and schwann cells still intact
- -monocytes enter from capillaries
- –macrophage cells engulf debris
Regeneration of Axon:
- ___ developes sprouts
- ___ undergo mitosis
- growth cone tip follows surface cues
- schwann cell attends to segment of new axon
- axon develops sprouts
- schwann cell undergoes mitosis
Damaged neuron will degenerate:
True or False- it will have less velocity(slower) then the original neuron
TRUE
A-alpha (I) nerve fiber
very fast
alpha motor
myotatic reflex (thick myline coated)
A-beta (II) nerve fiber
fast
deep touch
A-delta (III) nerve fiber
slow
light touch, fast pain
(IV) nerve fiber
very slow
slow pain
Neuromuscular Spindle:
- lies _____ to muscle fibers
- consists of:
- -_____ ____
- –annulospiral ending
- –A alpha sensory fiber
- -adjacent to ____ ___ is _____ mm fibers (do not move limb just change tension)
- –____ motor neurons
- –increases tension on ____ ____
- ______ mm fibers= move limb; innervated by ___ motor neurons
- lies parallel
- -nuclear bag
- -adjacent to nuclear bag is intrafusal mm fibers
- –gamma motor neurons
- extrafusual; by alpha motor neurons
Lower Motor Neuron
located in the ventral horn of the spinal cord (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem (cranial n. lower motor neurons)
Areflexia (LMN lesion)
-no reflex
Atonia (LMN lesion)
-no mm tone
Fasciculations (LMN lesion)
-mm undergo spontaneous contractions; both the mm and nerve die
Muscle Atrophy (LMN lesion)
-mm degenerates
LMN lesion results in (3)
- peripheral n
- anterior root
- anterior horn motor neuron (degenerates)
Myasthenia Gravis
autoimmune disease
-antibodies block acetylcholine receptors at neuromuscular junction
(risk-F age 20-40)
