Skeletal Muscle and Reflexes Flashcards
(110 cards)
1
Q
functional unit of cardiac & skeletal muscle
A
Sarcomere
2
Q
What type/size is the lower motor neuron that goes to muscle?
A
A-alpha
3
Q
What is the anatomical origin of the muscle from largest to smallest?
A
A.Whole Muscle B.Muscle Fascicles C.Muscle Fibers (Cells) D.Myofibrils E.Myofilaments (Thick and Thin) arranged in Sarcomeres
4
Q
Alternating ____ bands and _____ bands creates the striated appearance in skeletal and cardiac muscle.
A
A-bands and I-Bands
5
Q
Which band is the dark band?
A
A-band
6
Q
Which band is the light band?
A
I-band
7
Q
Sarcomere structure: Entire Length of Thick Filaments
A
A-Band (Dark)
8
Q
Sarcomere structure: Includes only Thin Filaments
A
I-Band (Light)
9
Q
Sarcomere structure: Only Thick Filaments
A
H-Zone
10
Q
Sarcomere structure: Thin Filaments Anchored Here
A
Z-Line
11
Q
Sarcomere structure: Link the Central Regions of Thick Filaments
A
M-Line
12
Q
Which band does not change in size in contraction?
A
A band
13
Q
In contraction, the zone of overlap _____
A
increases
14
Q
In contraction, I-Band _____
A
Decreases
15
Q
In contraction, H-Zone _____
A
Decreases
16
Q
The thin filament is composed of ____
A
actin, tropomyosin, and troponin
17
Q
____ are the active site which binds myosin)
A
G-actin molecules,
18
Q
______ binds actin, tropomyosin, and calcium).
A
troponin
19
Q
_____ filament has multiple cross-bridges where the “heads” can bind to the G-actin molecule; also functions as an ATPase enzyme.
A
myosin (thick)
20
Q
_____ Protein connects thin filaments to glycoproteins in sarcolemma
A
Dystrophin protein
21
Q
Which form of muscular dystrophy is associated with decreased dystrophin?
A
Beckers
22
Q
_____ are invaginations of muscle that allow the signal to get all the way into the middle of the sarcomere
A
T-tubules
23
Q
The alpha motor neuron releases ____ which binds to a _____ on the muscle fiber
A
ACh; nicotinic ACh receptor (NM)
24
Q
______ inhibits the release of ACH at the neuromuscular junction; can be used in dentistry (Bruxism, Sialorrhea, Masseteric Hypertrophy, etc.)
A
Botulinum toxin A
25
What are the 3 phases of muscle twitch?
Latent, contraction, and relaxation
26
In resting muscle, _____ prevents a strong bond between the myosin head and G-actin molecules
tropomyosin
27
When ______ binds to cytosolic Ca++, tropomyosin is pulled away from the myosin binding site, and allows for the power stroke
troponin
28
When troponin binds to cytosolic Ca++, _____ is pulled away from the myosin binding site, and allows for the power stroke
tropomyosin
29
When troponin binds to cytosolic Ca++, tropomyosin is pulled away from the myosin binding site, and allows for the ____
power stroke
30
Calcium is released from the ______ in muscle
Sarcoplasmic Reticulum
31
modified ER that sequesters Ca2+
Sarcoplasmic Reticulum (SR):
32
invaginations of sarcolemma
Transverse (T)-Tubules:
33
Portion of SR that contact T-tubules
Terminal Cisternae:
34
The AP travels down the membrane, down T-tubules, & activates voltage-sensitive ______ receptors on the T-tubules.
dihydropyridine (DHP)
35
dihydropyridine (DHP) receptors turn open calcium channels called _____ receptors on the SR.
(ryanodine receptors)
36
Calcium goes from SR to the ______.
sarcoplasm
37
(connection between actin and myosin)
cross-bridge
38
_____ binding to the myosin head breaks the cross-bridge
ATP
39
Energy released from _____ by the myosin head provides energy for cocking the myosin head
ATP hydrolysis
40
Release of inorganic _____ from the myosin head provides energy for the POWER STROKE
phosphate
41
(myosin head pulling actin towards the center of the sarcomere). This shortens the sarcomere.
POWER STROKE
42
Muscle cells only have enough ATP for about ____ twitch
8 twitches
43
Both _____ and _____ Metabolism produce ATP for muscle fibers.
Aerobic and Anaerobic metabolism
44
How many ATP are made from glycolytic fibers?
2 atp
45
How many ATP are made from oxidative fibers?
32-36
46
Besides metabolism, what is the other mechanism of ATP production for muscles
Phosphocreatine
47
Measurement of ______ levels in the blood is done to determine if damage to muscle tissue (skeletal and cardiac) has occurred (ex. heart attack or muscular dystrophy).
Creatine Kinase (CK)
48
_____ muscles:1.have decreased tension generation, 2.take longer to contract 3.relax more slowly and may not completely relax.
Fatigued
49
Theories for _____ include: Decreased ACH, Blockage of blood flow, increase in pH and lactic acid, increase in Potassium, Increased metabolic byproducts, and Depleted glycogen
fatigue:
50
Both ____ and ____ must be present for cross-bridge cycling.
Calcium and ATP
51
____ state: myosin and actin are tightly bound
Rigor State:
52
For relaxation of skeletal muscle, The _____ neuron must stop firing and Cytosolic (intracellular) ____ concentrations must decrease
alpha motor neuron; calcium
53
_____ on SR remove calcium from cytosol
Calcium ATPases
54
For relaxation to occur, ____ must be removed, but ___ must be present to release myosin from actin
Calcium; ATP
55
In rigor mortis, the rigor state is maintained due to lack of ____
ATP
56
Which type of muscle fiber is slow and oxidative; red, slow fatigue and slow myosin ATPase activity; moderate glycolytic capacity, high oxidative capacity
Type 1
57
Which type of muscle fiber is Fast and oxidative and glycolytic; red, fast resistant fatigue and fast myosin ATPase activity; high glycolytic capacity, moderate oxidative capacity
Type IIa
58
Which type of muscle fiber is Fast and glycolytic; white, fast fatigue and fast myosin ATPase activity; high glycolytic capacity, low oxidative capacity
Type IIb
59
Increase in size of muscle
Hypertrophy
60
Decrease in size of muscle
Atrophy
61
Atrophy due to an increase in age
Sarcopenia
62
thickness of the jaw muscles _____ significantly with age
decreases
63
The fibre-type composition of the jaw muscles also changes with age. In the jaw-closing muscles of elderly subjects, the proportion of pure type I fibres ______, while the proportion of pure type II fibres and that of hybrid fibres _____
decreases; increase
64
a ____ is the alpha motor neuron and the muscle fibers it innervates
motor unit
65
a motor unit is the _____ neuron and the muscle fibers it innervates
alpha motor neuron
66
What size of motor units are recruited first?
Small motor units
67
Smallest motor units control _____ fibers
fewer
68
An increase in the number of motor units activated increases the _____ produced by contraction of a muscle
total tension
69
An increase in the number of motor units activated increases the total tension produced by contraction of a muscle—_____ SUMMATION
SPATIAL summation
70
_____ motor units (X) are composed of slow-twitch oxidative fibers. They have the lowest threshold for firing and are recruited first.
Small motor units
71
____ motor units (Z) are composed of fast-twitch glycolytic fibers. They have the highest threshold and are recruited last
Larger motor units
72
T/F: Motor units in jaw muscles are restricted to specific areas of the jaw muscles, which permits differential control of separate muscle portions.
True
73
____ contraction Force produced is less than the load; no movement.
ISOMETRIC CONTRACTION.
74
______ contraction Force produced is great enough to move a load
ISOTONIC CONTRACTION.
75
The force of contraction increases until the ____ contraction becomes an ____ contraction—NOT always possible!
isometric; isotonic
76
the amount of load and the force the muscle generates determines the ____ of contraction.
type
77
In a ____ contraction, the muscle has not shortened; sarcomeres shorten, generating force, but elastic elements stretch, allowing muscle length to remain the same
Isometric contraction
78
In a ____ contraction, sarcomeres shorten more but because elastic elements are already stretched the entire muscle must shorten
Isotonic contraction
79
Increase total ____ of muscle contraction by (1) increasing the frequency of fiber activation and/or (2) increasing the number of muscle fibers contracting
force
80
An increase in the frequency of α motor neuron stimulation will increase the amount of ____ produced.
tension
81
The tension produced in response to each action potential will __ if the muscle has not yet completely relaxed
sum
82
_____ is where there is the best degree of overlap between the thick and thin filaments; at this point, there is an increased number of crossbridges that can form
Optimal length
83
At the optimal length the greatest number of actin/myosin cross-bridges can form, which results to _____ production
maximal tension production
84
____ is reduced if the muscle is not stretched enough or if it stretched too much
Tension
85
The ____ of contraction (distance moved/time) depends on the load a fiber is contracting against.
velocity
86
The greater the load, the ____ the speed of contraction.
SLOWER
87
Skeletal muscle fibers/cells that produce the contraction.
Extrafusal Fibers
88
Efferent neuron that releases ACh and causes contraction of the extrafusal fiber (skeletal muscle).
Alpha Motor Neuron:
89
Small structure within the extrafusal fibers that contains Intrafusal Fibers that have sensory nerve endings wrapped around them that are sensitive to CHANGES IN MUSCLE LENGTH.
Muscle spindle
90
Efferent neuron that causes contraction of intrafusal fibers so they mimic what the EF fibers are doing.
Gamma Motor Neuron:
91
____ fibers that have sensory nerve endings wrapped around them that are sensitive to CHANGES IN MUSCLE LENGTH
Intrafusal Fibers
92
Jaw closers have a lot of muscle _____
Spindles
93
When the muscle _____, the sensory fibers of the muscle spindle are squeezed.
stretches
94
If the _____ fibers did not contract, the sensory fibers would not be able to sense a further change in muscle length since they would be slack.
intrafusal fibers
95
The Effect of Muscle Spindle Activation is _____
Contraction
96
T/F: Anytime the alpha motor neuron is activated, the gamma motor neuron is also activated.
True
97
Mechanosensitive receptors found at the junction of tendons and muscle. Sensitive to a change in FORCE.
Golgi Tendon Organs:
98
The Golgi Tendon Organ Reflex is a _____ reflex.
protective
99
mastication is a cyclical movement with develops early in life. It is controlled by the _______ of the brainstem, which when stimulated, elicits rhythmic, coordinated activation and inactivation of jaw-closers and jaw-openers.
Central Pattern Generator (CPG)
100
_____ are important modifiers of force.
Reflexes
101
Input from higher cortical regions can regulate the CPG frequency via the ______ Pathway
Corticobulbar pathway
102
Jaw closer muscles have a lot of muscle ____
Muscle spindles
103
Jaw openers have ____ in low densities
Tendon organs
104
Pain inhibits the _____ neuron of jaw closing muscles such as when you bite down on your tongue, a metal spoon, with your incisors–Jaw opens
alpha motor neuron
105
Strong tap to the chin _____ the jaw closers–The jaw closers respond by contraction so the jaw closes
stretches
106
____ starts chewing by activating jaw closing muscles
CPG
107
____ fibers in muscle spindle are still contracting and stretching the muscle spindle so this signals further contraction of jaw closing muscles
Intrafusal fibers
108
______ decrease the contraction in situations where a lot of force is needed to crack something with the jaw
Muscle spindles
109
Powerful ____ contractions stimulate both jaw closing and opening muscles. The jaw openers keep the jaw from snapping shut.
isometric contracions
110
When you jog or run, force is applied to the mandible.–With each step, there is a down movement of the mandible in relation to the head.–This movement stretches the ______ which causes a reflex contraction of the jaw closing muscles.
muscle spindle
