Neurohistology

Question 1

what types of neurons are associated with sensory receptors?

Answer 1

bipolar and pseudounipolar neurons

Question 2

where are bipolar neurons located?

Answer 2

olfactory epithelium, retina, vestibular apparatus, cochlea

Question 3

where are type 1a / Aa fibers located?

Answer 3

myelinated fibers from annulospiral endings innervating muscle spindles

Question 4

where are type 1b / Aa fibers located?

Answer 4

myelinated fibers innervating Golgi tendon organs

Question 5

where are type 2 / AB fibers located?

Answer 5

myelinated fibers from flower spray endings innervating muscle spindles, cutaneous tactile receptors

Question 6

what is the function of type 3 / Ad fibers?

Answer 6

lightly myelinated fibers that relay pain, temperature, crude touch sensations

Question 7

what is the function of type 4 / C fibers?

Answer 7

unmyelinated fibers that relay pain and temperature sensations, and dull, poorly-localized pain

Question 8

nociceptors use what types of fibers?

Answer 8

Ad (lightly myelinated) and C (unmyelinated)

Question 9

mechanosensitive nociceptors use what type of fibers?

Answer 9

terminals of Ad fibers

Question 10

thermosensitive nociceptors use what type of fibers?

Answer 10

terminals of Ad fibers

Question 11

polymodal nociceptors use what type of fibers?

Answer 11

terminals of C fibers

Question 12

cold receptors use what type of fibers?

Answer 12

free nerve endings of Ad fibers

Question 13

warmth receptors use what type of fibers?

Answer 13

free nerve endings of C fibers

Question 14

where are Meissner’s corpuscles located?

Answer 14

dermal papillae

Question 15

where are Pacinian corpuscles located? what is their stimulus?

Answer 15

1. deep dermis, hypodermis, ligaments, IO membranes, external genitalia, joint capsules, pancreas 2. pressure, vibration, tickling

Question 16

where are Ruffini end organs located? what is their stimulus?

Answer 16

1. joint capsules, dermis, hypodermis of hairy skin 2. proprioceptive input

Question 17

extrafusal muscle fibers receive motor innervation from what type of neurons?

Answer 17

alpha motor neurons and pseudounipolar neurons

Question 18

what type of mechanoreceptor monitors muscle length?

Answer 18

muscle spindle

Question 19

static nuclear bag fibers are sensitive to what parameter?

Answer 19

changes in muscle length

Question 20

dynamic nuclear bag fibers are sensitive to what parameter?

Answer 20

rate of change in muscle length

Question 21

nuclear chain fibers are mostly sensitive to what parameter?

Answer 21

changes in muscle length

Question 22

when are annulospiral (primary) endings activated? what type of neuron provides the sensory innervation?

Answer 22

1. onset of muscle stretch or tension 2. type 1a

Question 23

when are flower spray (secondary) endings activated? what type of neuron provides the sensory innervation?

Answer 23

1. when stretch is in progress 2. type 2

Question 24

what provides motor innervation to intrafusal fibers?

Answer 24

gamma motor neurons

Question 25

GTOs receives sensory innervation via what type of neuron?

Answer 25

type 1b

Question 26

what it the function of GTOs?

Answer 26

monitor the amount of tension placed on a skeletal muscle

Question 27

what are the histological changes that occur during CNS degeneration?

Answer 27

1. 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