Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Caroline > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

Alpha and gamma neurons are what kind of neurons?

A

Motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the difference between Golgi tendon organs and Muscle Spindles

A

Both are sensory organs
Muscle spindle- detect stretch in muscle
GTO- Detect stretch in tendon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the joint kinesthetic receptors

A

Pacinian and ruffini corpusle

bare endings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Muscle spindles are ______ muscle fibers

A

Intrafusal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

True or false: muscle spindles contract in their central region

A

False, the central region is non-contractile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Type 2 sensory fibers go to what muscle spindles?

A

Nuclear chain and STATIC nuclear bag fibers

(not dynamic nuclear bag)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Type 1a fibers go to what muscle spindles?

A

All 3

Nuclear chain, static, and dynamic nuclear bag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Static gamma neurons innervate the contractile endings of what muscle spindles?

A

Static nuclear bag and nuclear chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Dynamic gamma neurons innervate the contractile endings of what muscle spindles?

A

dynamic nuclear bags

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

True or false: Sarcomeres are found inside of intrafusal muscle fibers

A

False. only in extrafusal

This is true?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do gamma motor neurons innervate?

A

The contractile ends of muscle spindles

slide says: “polar regions of intrafusal fibers”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Small diameter Alpha motor neurons (also called lower motor neurons) innervate what?

A

Extrafusal skeletal muscle fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Large diameter 1a and 2 fibers originate from the _____ region of muscle spindles

A

Central regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

A typical muscle spindle contains ____ nuclear bag and ____ chain fibers

A

2-3 nuclear bag and 5 chain fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Muscle spindles measure the velocity of stretch from phasic discharge of ____ fibers

A

1a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Muscle spindles measure the steady state length of muscle from tonic discharge of _______ fibers

A

1a and 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

1a’s have both ____ and _____ discharges

whereas 2’s only have ____ discharges

A

1a: Phasic and tonic

2: only tonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

True or false: Muscle spindles fire even when muscle fibers are relaxing

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Muscle spindles regulate _____________ neurons via feedback mechanism/stretch reflex

A

alpha motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Muscle spindles send input via sensory neurons to the spinal cord at the _________ horn and the spinal cord relays information to the muscle via alpha motor neurosn from the _______ horn

A

Dorsal horn (afferent)

Ventral horn (efferent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Gamma motor neurons control the ______ of the muscle spindles

A

Sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Dynamic gamma motor neurons increase the dynamic sensitivity of…

A

1a fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Static gamma motor neurons increase the tonic activity of….

A

Type 1a and 2

Note: also decreases the dynamic sensitivity of 1a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When extrafusal fibers shorten the intrafusal fibers _______

A

Are slack, do not fire as much

Note: less stretch = less firing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Without the sensory afferents of muscle spindles, the CNS cannot monitor information about….

A

Muscle length/position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

coactivation of gamma and alpha motor neurons ensure

A

appropriate length/tension relationship

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What causes reciprocal inhibitor?

Golgi Tendon Organs OR Muscle Spindles

A

Muscle Spindles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does reciprocal inhibition work?

A

Muscle spindles of agonist (example:quads) send signal to spinal cord

From the spinal cord a signal is sent that activates further contraction at the quads

AND it sends a signal via inter neurons to inhibit contraction of the antagonist (example:hamstrings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

True or false: reciprocal inhibition can occur voluntarily AND reflexively

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where are golgi tendon organs found?

A

At the junction between muscle fibers and tendons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What kind of neurons innervate the Golgi Tendon Organs?

A

1b fibers

33
Q

What do Golgi tendon organs do?

A

Autogenic inhibition or activation

The respond to force/muscle tension at the junction between the muscle and its tendon

They can either inhibit or activate the same muscle that they’re found in.

34
Q

True or false: both the Golgi tendons and the muscle spindles use fast conducting afferent nerves

A

True

35
Q

What is the ratio of muscles to motor neuron pool?

A

1:1

36
Q

all motor neurons within the muscle neuron pool innervate ____

A

a single muscle

37
Q

MNs innervating the axial muscles are located where in the ventral horn? what about distal muscles?

A

located medially

located laterally

38
Q

where are flexor muscles located in the ventral horn? extensors?

A

flexors located dorsally

extensors ventrally

39
Q

describe a motor unit

A

one alpha motor neuron and all the muscle fibers it innervates

40
Q

small motor units (not very many muscle fibers innervated) are used for what type of movement? what about larger motor units?

A

small = fine movements

large = gross movement

41
Q

What determines if a muscle fiber is fast/slow twitch?

A

the neuron innervating the muscle

motor neurons/UNITS (both) are classified as slow twitch or fast twitch depending on speed of contraction

so “both”…. but motor neurons.

42
Q

which fiber (type 1 or 2) can maintain levels of force for long periods of time?

A

type 1 (endurance)

43
Q

which muscle fiber (type 1 or 2) has a larger axon diameter?

A

type 2 (fast)

larger forces but fatigue quickly

44
Q

which muscle fibers are used for postural control?

A

endurance - type 1

45
Q

What NT is released from the presynaptic neuron in the NMJ?

A

Ach

46
Q

After being released into the NMJ, Ach binds to the muscle membrane, causing what?

A

Depolarization of the muscle membrane and then depolarization of the T-tubules in the muscle fiber

47
Q

What happens following the depolarization of T-tubules in the muscle cell?

A

voltage-gated channels open, releasing Ca+ from the sarcoplasmic reticulum (SR)

48
Q

To initiate a muscle contraction, ___ (what ion) binds to ___

A

Ca+

troponins

49
Q

What is rate coding?

A

MN signals amount of force to be exerted by muscle

(frequency of firing determines contraction strength)

50
Q

Tetanus

A

muscle is contracting maximally

51
Q

Force summation is caused by

A

higher firing rate

52
Q

How do slow vs fast twitch MNs compare with

time to peak-twitch force

contraction time

peak force

relative force summation

A

time to peak force: fast twitch have shorter time

contraction time: fast twitch have shorter twitch time

peak force: fast twitch generates higher forces

relative force summation: at lower frequencies, slower twitch form better summation

53
Q

What is recruited first, smaller or larger MNs?

Why is this the case?

A

smaller

V = IR, smaller motor neurons have large resistance (“R”), so a smaller current (“I”) will still lead to higher V

small amount of synaptic current will be sufficient to cause the potential of small MN to reach the firing threshold

54
Q

Z lines are ____ and are at the end of each sarcomere

Titin is ____ and anchors Z and M lines

A

fibrous

elastic

55
Q

Which filament has the “head” and which one slides inwards towards M line? (thick or thin)

A

Myosin heads connect with actin, pulling actin towards center

56
Q

What does Ca+ bind to in order to open active sites on actin?

A

Ca+ binds to troponin, causing tropomyosin to move off active sites

57
Q

Resistance to stretch in resting muscle is

A

muscle tone

58
Q

what determines the amount of muscle tone?

A

weak actin/myosin bonds at rest as well as titin

59
Q

How does contraction or immobility impact muscle tone/resistance to stretch?

A

resistance to stretch increases for a short time after prolonged contraction or immobility

longer immobility = more weak actin-myosin bonds exist

(Think about when you exercise and feel your muscles, and how you feel stiff in the morning getting out of bed)

60
Q

How are sarcomeres affected when patients are immobilized in a shortened position vs a lengthened positioned for a long time?

A

in a shortened position - lose sarcomeres

lengthened position - gain sarcomeres

61
Q

What 3 things in your body can restrict movement?

A

joint capsules, noncontractile tissue and antagonist muscles (co-contraction)

62
Q

T/F Cocontraction is a normal part of stabilizing a joint in function

A

T

63
Q

Reflexive movements make up a __ (small or large) percentage of our movements. Define reflexive movements

A

small

involuntary motor response to an external stimulus

64
Q

Spinal reflexes occur without what?

A

brain input

65
Q

T/F: patients with SCI can have spinal reflexes after time

A

T

66
Q

Describe the phasic stretch reflex

A

fast muscle stretch activates signals from the muscle spindles to alpha MNs for the same muscle causing a contraction

monosynaptic

67
Q

Describe the cutaneous withdrawal reflex

A

monosynaptic reflex in the SC that occurs in response to pain/noxious stimuli before conscious awareness of pain

68
Q

The following are examples of what?

  • muscle cramps
  • fasciculations
  • myoclonus
  • abnormal movements generated by dysfunctional basal ganglia
  • fibrillations
  • tremors
A

spontaneous involuntary muscle contractions

69
Q

What causes muscle cramps?

A

high frequency discharges of MNs overstimulated by sensory and motor input

healthy or pathologic

70
Q

What are fasciculations?

A

VISIBLE fast twitches of all muscle fibers in one motor unit

healthy or pathologic

71
Q

What is myoclonus?

A

brief involuntary contraction - muscle jerks when falling asleep, hiccups

healthy or pathologic

72
Q

what are fibrillations

A

NONVISIBLE, random, brief contraction so single muscle fibers

PATHOLOGIC

FIBRILation sounds like FIBER, single fiber

73
Q

What are tremors? List the three types

A

involuntary rhythmic movement that can occur at rest or with movement

postural - body part maintained against gravity (usually upper limb)
orthostatic - standing, (usually lower limbs)
intention - absent at rest, worsen when target is approached

74
Q

Conditions affecting the ___ ____ and ______ (what two brain structures) also present with tremor?

A

basal ganglia and cerebellum

75
Q

List common signs of lower motor neuron lesions

A

hypoflexia or areflexia

paresis or paralysis

muscle atrophy

decrease or loss of muscle tone (hypotonia/flaccidity)

fibrillations

76
Q

What do motor nerve conduction velocities/studies measure?

A

measure the speed and strength of electrical signals traveling through MNs to muscles

77
Q

Why might an EMG be done for a patient with motor issues?

A

diagnostically differentiate between denervated muscle or myopathy

“muscle not working does not mean the neuron is not working”

78
Q

What part of the nervous system does polio attack?

A

LMNs (at the ventral horn)

79
Q

What are the affects of the polio virus and how does it lead to PPS? (post-polio syndrome)

A

polio causes death of selected MNs, your body then forms giant motor units from remaining MNs (neuroplasticity effect)

PPS - over time the giant MNs die off due to their excessive oxygen needs, causing fatigue, weakness and pain

Caroline (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions