Brainscape's Knowledge GenomeTM

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


See full index

Neurobiology > Chapter 13: Spinal Control of Movement > Flashcards

Chapter 13: Spinal Control of Movement Flashcards

1
Q

Flexor muscles of the arm:

A
  1. brachialis
  2. biceps brachii
  3. coracobrachialis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The three flexor muscles or two extensor muscles are called…

A

synergists

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

Extensor muscles:

A
  1. triceps brachii

2. anoconeus

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

Relationship of flexors and extensors:

A

antagonists to one another

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

Muscles that are responsible for movements of the trunk…

Important for…

A

axial muscles

maintaining posture

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

Muscles that move the should, elbow, pelvis, and knee are called…

Important for…

A

proximal or girdle muscles

critical for locomotion

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

Muscles that move hands, feet, and digits are called…

Important for…

A

distal muscles

manipulation of objects

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

Alpha motor neurons function:

A

directly trigger the generation of force by muscles

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

Motor unit:

A

one alpha motor neuron and all the muscle fibers it innervates; elementary component of motor control

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

Motor neuron pool:

A

collection of alpha motor neurons that innervates a single muscle

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

The first way the CNS controls muscle contraction is by […].

The second way the CNS grades muscle contraction is by […].

A

varying the firing rate of motor neurons

recruiting additional synergistic motor units

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

Alpha motor neurons communicates by releasing…

A

ACh at the NMJ

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

ACh release in response to one presynaptic AP causes an […].

A

EPSP or end plate potential

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

Muscles with a large number of small motor units…

A

can be finely controlled by the CNS

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

What is the size principle?

A

orderly recruitment of motor neurons is due to variations in alpha motor neuron size

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

What are the three major sources of input to an alpha motor neuron?

A
  1. dorsal root ganglion cells– axons that innervate a specialized sensory apparatus (muscle spindle)
  2. upper motor neurons– in cortex and brain stem
  3. largest; interneurons in the spinal cord (excite/inhibit)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Fast motor units contain […].

Slow motor units contain […].

A

rapidly fatiguing white fibers

slowly fatiguing red fibers

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

Fast motor unit properties:

Slow motor unit properties:

A
  1. bigger
  2. larger diameter
  3. faster-conducting axons

the exact opposite

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

Fire unit properties of fast motor units:

A

F: generate occasional high-frequency bursts of AP (30-60 impulses per second)

S: relatively steady; low-frequency activity (10-20 impulses per second)

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

Normal innervation of a fast muscles was replaced with a slow muscle innervation… what occurs?

A

switch in phenotypes a consequence of synaptic activity

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

Hypertrophy:

A

exaggerated growth; long-term consequence of increased activity

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

Atrophy:

A

degeneration; prolonged inactivity

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

Excitation-contraction coupling:

A

AP/excitation triggers the release of Ca2+ from an organelle inside the muscle fiber

leads to contraction of the fiber

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

When does excitation-contraction coupling occur?

A

ACh release — activation of nicotinic ACh — EPSP — ECC occurs here — Ca2+ release

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

Muscle fibers are enclosed by an excitable cell membrane called […].

A

sacrolemma

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

Within the muscle fiber are a number of cylindrical structures called […], which contract in response to an […].

A

myofibrils; AP firing down the sacrolemma

27
Q

Myofibrils are surrounded by the […].

A

sarcoplasmic reticulum

28
Q

Sarcoplasmic reticulum:

A

extensive intracellular sac that stores Ca2+

29
Q

How are AP able to make it to SR?

A

T tubules

30
Q

Sliding filament model meaning:

A
  1. binding of Ca2+ to troponin causes myosin to bind to actin
  2. myosin “heads” pivot, cause filaments to slide
  3. repetition of process “walks” myosin heads along filament
31
Q

The sliding of filaments occurs due to…

A
  1. interaction between the major thick filament MYOSIN and major thin filament ACTIN
  2. MYOSIN heads molecules bind ACTIN molecules and then undergo a conformational change
  3. pivot causes filament movement; ATP allows the cycle to repeat
32
Q

Why can’t myosin interact with actin at rest?

A

actin molecule is covered by troponin

33
Q

How does Ca2+ initiate muscle contraction?

A

binds to troponin; exposing myosin head for interaction

34
Q

Contraction continues as long as what is present?

Relaxation occurs when?

A

Ca2+ and ATP

Ca2+ is sequestered by the sarcoplasmic reticulum (needs ATP too)

35
Q

List the steps that take place for excitation:

A
  1. AP occurs in the alpha motor neuron axon
  2. ACh is released by the end plate at the NMJ
  3. Nicotinic receptor channels in the sarcolemma open, and the postsynaptic sarcolemma depolarizes (EPSP)
  4. Voltage-gated sodium channels open, an AP is generated in the muscle fiber, which sweeps down the sarcolemma and into the T tubule
  5. Depolarization of the T tubules causes Ca2+ release from the sarcoplasmic reticulum
  6. Contraction
  7. Ca 2+ reuptake
  8. Fiber relaxes
36
Q

List the steps that take place for contraction:

A
  1. Ca2+ binds to troponin
  2. myosin binding sites on actin are exposed
  3. myosin heads bind actin
  4. myosin heads pivot
  5. myosin heads disengage at the expense of ATP
  6. continuous ONLY IF Ca2+ and ATP are present
37
Q

List the steps that take place for relaxation:

A
  1. EPSP end; sarcolemma and T tubules return to their resting potentials
  2. Ca2+ sequestered by the sarcoplasmic reticulum by an ATP-driven pump
  3. Myosin binding site on active are covered by troponin
38
Q

Muscle spindle:

A

stretch receptor; specialized for the detection of changes in muscle length

**an example of proprioceptors

39
Q

Intrafusal fibers:

A

receive their motor innervation by another type of lower motor neuron

40
Q

Intrafusal fibers vs extrafusal fibers:

A
  1. more extraf than intraf
  2. extraf fibers are innervated by alpha motor neurons
  3. intraf fibers are innervated by gamma motor neurons
41
Q

Gamma motor neuron:

A

low motor neuron;

42
Q

Red muscle fibers:

A
  1. large number of mitochondria and enzymes
  2. slow to contract
  3. can sustain contraction
43
Q

White muscle fibers:

A
  1. fewer mitochondria
  2. anaerobic metabolism
  3. contract and fatigue rapidly
44
Q

Fatigue-resistant fast fibers:

A

white fibers with moderate strength and fast contractions

45
Q

Fast fatigable fibers:

A

fastest, strongest, white fibers, but rapidly fatiguing

46
Q

Slow motor units:

A

slow fatiguing red fibers

47
Q

Type of motor units:

Which motor unit type exists in most muscles?

A
  1. fatigue-resistant fast fibers
  2. fast fatigable fibers
  3. slow motor units

all three coexist

48
Q

Two categories of lower motor neurons of the spinal cord:

A
  1. alpha motor neurons

2. gamma motor neurons

49
Q

Motor neurons of the […] units are generally the biggest and have the largest diameter, fastest conducting axons.

A

FF

50
Q

Motor neurons of the […] units have motor neurons and axons intermediate in size.

A

FR

51
Q

[…] units have small-diameter, slowly conducting axons.

A

small

52
Q

[…] motor neurons tend to generate occasional high-frequency bursts of action potentials (30-60 impulses per second).

A

FF

53
Q

[…] motor neurons are characterized by relatively steady, low-frequency activity (10-20 impulses per second).

A

slow

54
Q

A crossed-innervation experiment:

A

forcing slow motor neurons to innervate a fast muscle causes muscles to switch phenotype and slow properties

55
Q

Hypertrophy:

A

exaggerated growth of muscle fibers from long term increased activity

56
Q

Atrophy:

A

degeneration of muscle fibers from prolonged inactivity

57
Q

Z lines:

A

division of myofibril into segments by disks

58
Q

Sarcomere:

A

two Z lines and myofibril

59
Q

Thin filaments:

A

series of bristles anchored to Z lines

60
Q

Thick filaments:

A

between and among thin filaments

61
Q

Stretch reflex:

A
  1. muscle pulled there is a tendency to pull back
  2. feedback loop
  3. monosynaptic
  4. discharge rate of sensory axons related to length
62
Q

Golgi tendon organs:

A

additional proprioceptive input (strain gauge) monitors and regulated muscle tension

63
Q

What type of axon is attached to a golgi tendon organ?

A

I beta axon

Neurobiology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions