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PHYSIOLOGY III > L10: Organization of the Nervous System / Spinal Reflex Connections > Flashcards

L10: Organization of the Nervous System / Spinal Reflex Connections Flashcards

1
Q

division of the PNS that carries info from the sensory receptors in the skin, skeletal muscles and joints to the CNS; composed of sensory neurons

A

Afferent

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2
Q

division of the PNS that transmits impuses from the CNS to the effector organs

A

efferent

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3
Q

what are the two divisions of the efferent NS

A

Somatic NS: fibers of motor neurons that supply skeletal muscles
Autonomic NS: fibers that innervate smooth muscle,, cardiac and glands

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4
Q

excitable cells that transmit electrical impulses, the functional units of the NS

A

Neurons

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5
Q

cells that communicate w/ and support the neurons

A

neuroglia

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6
Q

soma

A

cell body
contains nucleus and most organelles

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7
Q

what does it mean for neurons to be amitotic

A
  • they don’t divide to create more neurons
  • they lack centrioles - an organelle needed for cell division
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8
Q

outgrowths of neuronal processes from the soma

A

dendrites

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9
Q

sites that receive inputs from other neurons; are the site of synapses

A

dendritic spines

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10
Q

the axon is the primary _________ output

A

neuronal

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11
Q

transport substances within the axon

A

microtubules

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12
Q

synaptic terminals release ?

A

NTs

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13
Q

more neurons or neuroglia?

A

neuroglia, 10x more than neurons

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14
Q

do neuroglia initiate or conduct APs?

A

no

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15
Q

5 major classes of neuroglia

A

CNS glia:
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
PNS glia:
- Schwann cells

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16
Q

neurons have a well developed ______ and _______ since they are major biosynthetic centers for neuropeptides

A

Golgi apparatus & Rough ER

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17
Q

most abundant of the neuroglia

A

astrocytes

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18
Q

neuroglia that are the ‘immune system’ of the NS

A

microglia

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19
Q

neuroglial cells that are capable of dividing and therefore are the source of all new neurons

A

Ependymal cells

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20
Q

Both the ______ & ________ glial cells produce a protective sheath over the axons, allowing for increased speed of transmission of APs (myelination)

A

Oligodendrocytes (CNS) and Schwann cells (PNS)

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21
Q

what glial cells make up the white matter

A

Oligodendrocytes & schwann cells

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22
Q

3 fiber types that occur in the PNS

A

A, B, C
characterized based on how theri axons are myelinated (A being the ‘thickest’, C being the ‘thinnest’

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23
Q

Aα fibers are the ______, Aδ are the _________ in diameter

A

alpha - largest in diameter (and fastest)
delta - smallest in diameter (slower)

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24
Q

Aα fibers carry what information

A

muscle spindle and golgi tendon info

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25
Q

Aβ fibers carry what info

A

musle spindle, touch and proprioception
mechanoreceptors of the skin

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26
Q

Aδ carry what info

A

pain and temperature
- mechanical nociceptors

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27
Q

C fibers are small and _______

A

non myelinated = slow

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28
Q

C fibers cary info on..?

A

pain

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29
Q

what things does each spinal nerve have?

A
  • dorsal root (dorsal horn)
  • ventral root (ventral horn)
  • relay circuits
  • ganglia
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30
Q

where do upper motor neurons originate

AKA Pyramidal tract

A

primary motor cortex

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31
Q

what do UMNs control

A

skeletal muscle tone and consious skilled movements

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32
Q

what are corticospinal nerves most important for (type of movement)

A

intentional movements

33
Q

where do lateral corticospinal nerves cross

A

at the medulla

34
Q

where do ventral corticospinal nerves cross?

A

at the level of termination in the spinal cord

35
Q

UMNs synapse at _____ in the spinal cord

A

Lower motor neurons

36
Q

axons of the lower motor neurons exit at the _____ and go on to the PNS

A

Ventral horns

37
Q

T/F: contralateral control of the skeletal muscle movements occurs in both the lateral and ventral corticospinal tracts

A

T

38
Q

both the lateral and ventral corticospinal tracts are involved in the _______ control of skeletal muscles

A

voluntary

39
Q

what is canine degenerative myelopathy

A
  • damage to the spinal cord that causes the pathways b/w body and brain to get interrupted
  • progressive demyelination of the spinal cord
  • spastic paresis
  • exaggerated reflexes
40
Q

Canine degenerative myelopathy is characterized by _____motor neuron paralysis localized to the T3-L3 spinal segments

A

upper motor neuron

41
Q

when diagnosing DM, what is important to rule out

A

spinal compression which is when large diameter fibers lose function before small diameter fibers

42
Q

what is feline diabetic neuropathy

A

demyelination of distal axons associated w/ diabetes mellitus
* plantigrade and palmigrade stance
* can progress to tetraparesis where all 4 limbs are affected

43
Q

why is feline diabetic neuropathy also associated w/ sensory nerve disfunction

A

b/c sensory NS is part of the peripheral part of the body

44
Q

what are the 2 types of reflexes

A
  • simple/basic: built in, unlearned
  • acquired/conditioned: result of practice or learning
45
Q

what are the 5 components of the neural pathway involved in reflex activity

A
  • receptor
  • afferent pathway
  • integrating center
  • efferent pathway
  • effector
46
Q

what are golgi tendon organs

A
  • proprioceptors (detect position of the body)
  • measure the tension in muscle
47
Q

what are muscle spindles

A
  • proprioceptors
  • located within a muscle tissue parallel to muscle fibers
  • spindle consists of contractile ends and a non-contractile middle portion with sensory innervation
48
Q

the contractile ends of muscle spindles are innervated by what kind of motor neurons

A

γ (gamma)

49
Q

what is the non-contractile middle portion of a muscle spindle innervated by

A

type 1a and II afferent sensory fibers

50
Q

α-motor neurons innervate the ________skeletal muscle fibers

A

extrafusal

51
Q

what happens to cause a muscle to contract

A

motor impulse (afferent input) comes down spinal cord, excited extrafusal fibers
another impulse causes intrafusal muscle spindle fibers to contract
spindles are shortened but remain sensitive to stretch at all muscle lengths

52
Q

group 1A afferent sensory receptors innervate both **nuclear bag and nuclear chain fibers **and detect ?

A

the velocity of length change

53
Q

Group 2 afferent sensory receptors innervate nuclear chain fibersand detect?

A

the length of the muscle fiber

54
Q

when a muscle is stretched, both group ___ and ___ afferents are activated

A

1A and 2

55
Q

motor innervation includes _____ γ motorneurons that innervate nuclear____fibers and _______ γ motorneurons that inenrvate nuclear _____ fibers

A

static - chain
dynamic - bag

56
Q

A-motor neurons activates ______fibers causing them to shorter
at the same time, to keep tension in spindles constant, the γ motor neurons activate the _______ fibers, causing them to shorter

A

extrafusal
intrafusal

57
Q

the monosynaptic stretch reflex (aka myotactic) is important in maintaining ______ and muscle tone

A

posture

58
Q

during the monosynaptic stretch reflex, the stretch is measured by?

A

muscle spindles (intrafusals) - length detectors

59
Q

activated muscle spindles activate the ____neuron of a stretched muscle

A

motor

60
Q

profective reflex in response to the stretch of muscles

A

Polysynaptic stretch reflex

61
Q

the polysnyaptic stretch reflex is composed of two or more synapses that allow for ______ innervation

A

reciprocal

62
Q

during the polysynaptic stretch reflex, extensors are activated while the opposing flexor muscle is ______

A

inhibited

63
Q

are polysynaptic reflexes faster or slower than monosynaptic reflexes

A

slower

64
Q

what reflex involves nociceptors (free nerve endings)

A
  • flexor withdrawal reflex
  • ex: pulling hand away from flame
  • limb withdrawal occurs by the simultaneous activation and relaxation of opposing muscles
65
Q

what reflex allows weight to be shifted to the uninjured limb so you don’t fall

A

the flexor withdrawal/crossed extensor reflex

66
Q

pathway in the spinal column responsible for touch, pressure vibration, 2 point discrimination and proprioception

A

dorsal lemniscus columns

67
Q

ascending pathway responsible for touch

A

ventral spinothalamic (crossed)

68
Q

ascending pathway responsible for pain and temp

A

lateral spinothalamic (crossed)

69
Q

what are the 3 ascending afferent pathways?

A
  • lateral lemniscus columns
  • lateral spinothalamic
  • ventral spinothalamic
70
Q

when performing a noxious stimulus to test the crossed extensor reflex, what reaction would you expect to see if a patient had an upper motor neuron lesion?

A

exaggerated reflex due to a lack of control of the relex by UMNs and or a lack of awareness of the stimulus

71
Q

a segmental reflex transverses ____ or _____ segments or brain divisions

A

one or few

72
Q

an intersegmental reflex transverses several segments of the _______ or several brain divisons

A

spinal cord

73
Q

a long-loop intersegmental reflex transverses many segments of the ______ and or brain divisions; enters and exits the CNS at the same location

A

spinal cord

74
Q

proprioceptors carry info on ______ while nociceptors carry info on _______

A

movement
pain

75
Q

free nerve endings in joint capsules and in the skin are what type of receptors

A

nociceptors (pain)

76
Q

what root/horn (dorsal or ventral) carries afferent

A

dorsal

77
Q

what root/horn (dorsal or ventral) carries efferent

A

Ventral

78
Q

why are C fibers the slowest

A

not myelinated

79
Q

a bunch of intrafusal muscles fibers is a …

A

muscle spindle

PHYSIOLOGY III (31 decks)

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