Motor Physiology Flashcards
1
Q
Skeletal muscle fiber that functions to detect muscle length
A
Muscle spindle (intrafusal) (5%)
2
Q
Skeletal muscle fiber for muscle contraction
A
Extrafusal (95%)
3
Q
Fast-twitch or slow-twitch?
Glycolytic, white, Type II
A
Fast-twitch
4
Q
Fast-twitch or slow-twitch?
Oxidative, red, Type I
A
Slow-twitch
5
Q
Fast-twitch or slow-twitch?
2x larger
A
Fast-twitch
6
Q
Fast-twitch or slow-twitch?
Faster SR calcium reuptake
A
Fast-twitch
7
Q
Fast-twitch or slow-twitch?
Enzymes are 2-3x more active in phosphagen and glycogen-lactic acid energy systems
A
Fast-twitch
8
Q
Fast-twitch or slow-twitch?
Enzymes are more active in aerobic system
A
Slow-twitch
9
Q
Fast-twitch or slow-twitch?
Myosin ATPase is high
A
Fast-twitch
10
Q
Fast-twitch or slow-twitch?
Has more mitochondria, myoglobin, capillaries
A
Slow-twitch
11
Q
Fast-twitch or slow-twitch?
For power
A
Fast-twitch
12
Q
Fast-twitch or slow-twitch?
For endurance
A
Slow-twitch
13
Q
Fast-twitch or slow-twitch?
EOMs
A
Fast-twitch
14
Q
Fast-twitch or slow-twitch?
Soleus, antigravity muscles of the back
A
Slow-twitch
15
Q
Why is the atria able to contract separately from the ventricles?
A
Lack of gap junction between the atria and ventricles
16
Q
Type of smooth muscle used for fine-control, (-) gap junctions
A
Multi-unit smooth muscle
17
Q
Type of smooth muscle used for gross/coarse-control, (+) gap junctions
A
Unitary smooth muscle/Syncitial smooth muscle/Visceral smooth muscle
18
Q
Multi-unit or Unitary smooth muscle?
One nerve, multiple muscle fibers that may act on their own
A
Multi-unit
19
Q
Multi-unit or Unitary smooth muscle?
One nerve, multiple muscle fibers that act together as one
A
Unitary
20
Q
Multi-unit or Unitary smooth muscle?
Controlled mainly by nerve signals (Ach, NE)
A
Multi-unit
21
Q
Multi-unit or Unitary smooth muscle?
May be controlled by nerve signals, hormones, stretch, local factors
A
Unitary
22
Q
Multi-unit or Unitary smooth muscle?
No true action potential (no propagation); junctional potential only
A
Multi-unit
23
Q
Multi-unit or Unitary smooth muscle?
Slow waves, spike potentials, plateau potentials
A
Unitary
24
Q
Multi-unit or Unitary smooth muscle?
May exhibit spontaneous contractions
A
Unitary
25
Multi-unit or Unitary smooth muscle?
| Uterus, intestines, bile ducts, ureters
Unitary
26
Multi-unit or Unitary smooth muscle?
| ciliary eye muscle, iris, piloerector muscle, vas deferens
Multi-unit
27
Type of smooth muscle that is rhythmic and intermittent; ex. walls of the GI and urogenital tracts
Phasic smooth muscle
28
Type of smooth muscle that is continuously active; ex. vascular smooth muscle, respiratory smooth muscles, sphincters
Tonic smooth muscle
29
What is the arrangement from sarcomere to skeletal muscle?
Sarcomere --> Myofibril --> Muscle fiber --> Muscle fascicle --> Skeletal muscle
30
What is the connective tissue that surrounds the muscle fiber?
Endomysium
31
What is the connective tissue that surrounds the muscle fascicle?
Perimysium
32
What is the connective tissue that surrounds the skeletal muscle?
Epimysium
33
What is the plasma membrane surrounding the muscle fiber?
Sarcolemma
34
These are invaginations of the sarcolemma in close proximity to the terminal cisternae of the sarcoplasmic reticulum
Transverse tubules
35
Endoplasmic reticulum surrounding myofibril which contains calcium
Sarcoplasmic reticulum
36
Functional unit of the muscle; area between two Z lines
Sarcomere
37
Thick filaments are also called:
Myosin
38
Three kinds of thin filaments:
Actin, Tropomyosin, Troponin
39
Thick filaments are centered on the ___ line but will never reach the ___ line
M line, Z line
40
Thin filaments are centered on the ___ line but will never reach the ___ line
Z line, M line
41
Serve as borders of sarcomere where actin will attach
Z line/ Z disk
42
Area of the sarcomere that contains only thick filaments
H band
43
Area of the sarcomere that contains thick filaments but no myosin heads
Bare zone
44
Entire length of the myosin
A band
45
Area of the sarcomere that contains only thin filaments
I band
46
Center of the sarcomere
M line
47
Troponin which attaches troponin complex to tropomyosin
Troponin T
48
Troponin which inhibits actin-myosin binding
Troponin I
49
Troponin which is a calcium-binding protein
Troponin C
50
Tethers myosin to Z lines; binds Z lines to M lines; largest protein in the body
Titin
51
Stabilizes sarcolemma and prevents contraction-induced rupture
Dystrophin
52
Binds actin to Z lines
Actinin, Cap Z protein
53
Binds Z lines to sarcolemma
Desmin
54
Act as a molecular ruler that sets the length of actin during assembly
Nebulin
55
The negative pole is the area near the ___ line, while the positive pole is the area near the ___ line
M line, Z line
56
When myosin heads pull on actin towards the negative pole, the sarcomere shortens. The following changes also happen.
I band is: ________
H band is: ________
A band is: ________
I band is obliterated
H band is shortened
A band remains the same
57
Skeletal muscle contraction involves motor neurons and extrafusal fibers. This is demonstrated by:
Sliding filament model
58
What do you call the actin and myosin interaction?
Cross-bridge formation
59
During depolarization of a skeletal muscle, what receptor is activated in the transverse tubules?
Dihydropyridine receptor (DHPR)
60
During depolarization of a skeletal muscle, what receptor is activated in the sarcoplasmic reticulum?
Ryanodine receptor
61
What acts as a "gate" preventing actin and myosin interaction during rest state, and exposes the binding site during skeletal contraction.
Tropomyosin
62
What do you call the state where myosin is permanently bound to actin?
Rigor mortis
63
Once ATP binds with myosin, the myosin-actin bind is disrupted. This event happens when there is partial hydrolysis of ATP bound to myosin.
Recocking (myosin head displaced toward + end of actin)
64
Complete hydrolysis of ATP results in this event:
Powerstroke (pulling of the actin towards the M line)
65
What is the distance achieved in each cross-bridge cycle?
10 nanometers
66
Made up of alpha motor neuron (lower motor neuron), its axon and all muscle fibers it supplies
Motor unit
67
Small motor units are recruited first before big motor units
Size principle
68
Multiple fiber summation
Spatial summation
69
Frequency summation
Temporal summation
70
Each contraction occurs after complete relaxation producing stronger contraction each time
Staircase (Treppe) effect
71
Basis for Treppe effect
Ca2+ accumulation, pH changes, increased temperature
72
Complete fusion of individual muscle contraction when Ca2+ is all used up
Tetany
73
Which of the following tetanizes at lower stimulus frequency, slow-twitch or fast-twitch fibers?
Slow-twitch
74
Which of the following has larger maximal force during tetany, slow-twitch or fast-twitch fibers?
Fast-twitch
75
What happens to passive tension, active tension, and force of contraction whenever a muscle is stretched?
```
Passive tension (tension developed when muscle is stretched): increases
Active tension (tension developed when muscle is contracted): decreases
Force of contraction: increases
```
76
Active tension and velocity of contraction reflect what?
Active tension: # of cross-bridges that cycle
| Velocity of contraction: speed of cross-bridge cycling
77
What happens to velocity of contraction if afterload is increased?
decreases
78
Differentiate isometric contraction from isotonic contraction
Isometric: length is held constant
Isotonic: load is held constant
79
Muscle shortening is called ________, while muscle lengthening is called _________
shortening: concentric contraction
lengthening: eccentric contraction
80
When lifting a weight, what kind of contraction is happening?
Isometric contraction, followed by isotonic contraction
81
Protective mechanism to prevent muscle cell injury or death
Muscle fatigue (occurs earlier in fast-twitch fibers)
82
Muscle fatigue is _____ proportional to lactic acid levels and _____ proportional to muscle glycogen levels and creatine phosphate stores
directly proportional to lactic acid levels
| inversely proportional to muscle glycogen levels
83
What mechanisms increase Ca2+ influx to the cardiac muscle?
L-type or slow or long-acting calcium channel (predominant)
| T-type or fast or transient calcium channel
84
What mechanisms increase Ca2+ efflux to the ECF?
3Na-1Ca countertransport
| Ca-ATPase pump
85
Cardiac muscle vs Skeletal muscle:
| More developed Transverse tubules
Cardiac muscle
86
Cardiac muscle vs Skeletal muscle:
| More developed sarcoplasmic reticulum
Skeletal muscle
87
Cardiac muscle vs Skeletal muscle:
| Syncitium present
Cardiac muscle
88
Cardiac muscle vs Skeletal muscle:
| Can have tetany
Skeletal muscle
89
Cardiac muscle vs Skeletal muscle:
| Electromechanical coupling via Ca-induced, Ca-release
Cardiac muscle
90
Cardiac muscle vs Skeletal muscle:
| Electromechanical coupling via DHPR and RYR interaction
Skeletal muscle
91
Cardiac muscle vs Skeletal muscle:
| Transverse tubules located in the Z lines
Cardiac muscle
92
Cardiac muscle vs Skeletal muscle:
| Transverse tubules located in the end of I bands
Skeletal muscle
93
Why is there no tetany in cardiac muscles?
Long refractory period brought about by Phase 2
94
Substance that adds a phosphate to myosin in smooth muscles to during contraction
Myosin light chain kinase
95
Substance that cleaves off phophate from myosin in smooth muscles for relaxation
Myosin light chain phosphatase
96
Smooth muscle equivalent of Troponin I which inhibits actin-myosin binding
Caldesmon, Calponin
97
Smooth muscle equivalent of Troponin C which binds to ECF Ca2+
Calmodulin
98
Smooth muscle equivalent of z discs of skeletal muscles
Dense bodies
99
Rudimentary t-tubules in smooth muscles
Caveoli
100
Connect dense bodies with cytoskeletal network
Intermediate filaments (Desmin and Vimentin)
101
Smooth muscles vs Skeletal muscles:
| Uses more ATP
Skeletal muscles
102
Smooth muscles vs Skeletal muscles:
| Onset of contraction is faster
Skeletal muscles
103
Smooth muscles vs Skeletal muscles:
| Duration of contraction is longer
Smooth muscles
104
Smooth muscles vs Skeletal muscles:
| Force of contraction is stronger
Smooth muscles (4-6kg/cm2 vs 3-4kg/cm2 in skeletal muscles)
105
Anterior motor neurons:
Alpha motor neurons for _____ fibers
Gamma motor neurons for _____ fibers
```
Alpha = extrafusal
Gamma = intrafusal
```
106
Facilitate lateral inhibition
Renshaw cell
107
Sense of awareness of position of body in space
Proprioception
108
Provide the CNS with information regarding muscle length, position and tension (force)
Proprioceptors
109
Type of proprioceptor which is arranged in a parallel manner to extrafusal muscle fibers, and detects changes in muscle length and rate of change in muscle length
Muscle spindles
110
Type of proprioceptor which is arranged in a series manner to extrafusal muscle fibers, and detects changes in muscle tension
Golgi tendon
111
The silent area of the brain; sequences motor activity, monitors and adjusts motor activities as they are performed
Cerebellum
112
Functional unit of the cerebellum
Purkinje (middle layer, always inhibitory), and Deep nuclear cell
