Neurohistology Flashcards
what types of neurons are associated with sensory receptors?
bipolar and pseudounipolar neurons
where are bipolar neurons located?
olfactory epithelium, retina, vestibular apparatus, cochlea
where are type 1a / Aa fibers located?
myelinated fibers from annulospiral endings innervating muscle spindles
where are type 1b / Aa fibers located?
myelinated fibers innervating Golgi tendon organs
where are type 2 / AB fibers located?
myelinated fibers from flower spray endings innervating muscle spindles, cutaneous tactile receptors
what is the function of type 3 / Ad fibers?
lightly myelinated fibers that relay pain, temperature, crude touch sensations
what is the function of type 4 / C fibers?
unmyelinated fibers that relay pain and temperature sensations, and dull, poorly-localized pain
nociceptors use what types of fibers?
Ad (lightly myelinated) and C (unmyelinated)
mechanosensitive nociceptors use what type of fibers?
terminals of Ad fibers
thermosensitive nociceptors use what type of fibers?
terminals of Ad fibers
polymodal nociceptors use what type of fibers?
terminals of C fibers
cold receptors use what type of fibers?
free nerve endings of Ad fibers
warmth receptors use what type of fibers?
free nerve endings of C fibers
where are Meissner’s corpuscles located?
dermal papillae
where are Pacinian corpuscles located? what is their stimulus?
- deep dermis, hypodermis, ligaments, IO membranes, external genitalia, joint capsules, pancreas 2. pressure, vibration, tickling
where are Ruffini end organs located? what is their stimulus?
- joint capsules, dermis, hypodermis of hairy skin 2. proprioceptive input
extrafusal muscle fibers receive motor innervation from what type of neurons?
alpha motor neurons and pseudounipolar neurons
what type of mechanoreceptor monitors muscle length?
muscle spindle
static nuclear bag fibers are sensitive to what parameter?
changes in muscle length
dynamic nuclear bag fibers are sensitive to what parameter?
rate of change in muscle length
nuclear chain fibers are mostly sensitive to what parameter?
changes in muscle length
when are annulospiral (primary) endings activated? what type of neuron provides the sensory innervation?
- onset of muscle stretch or tension 2. type 1a
when are flower spray (secondary) endings activated? what type of neuron provides the sensory innervation?
- when stretch is in progress 2. type 2
what provides motor innervation to intrafusal fibers?
gamma motor neurons
GTOs receives sensory innervation via what type of neuron?
type 1b
what it the function of GTOs?
monitor the amount of tension placed on a skeletal muscle
what are the histological changes that occur during CNS degeneration?
- microglia clean up debris 2. no basal lamina or Schwann cell guidling tunnels present in CNS 3. oligodendrocytes release an inhibiting factor 4. astrocytes may not release enough GF 5. astrocytic scar tissue replaces damaged tissue
