Muscle Physio Flashcards
(98 cards)
1
Q
Skeletal muscle is the predominant site of
A
Thermogenesis
2
Q
3 types of muscle tissue
A
Smooth
Cardiac
Skeletal
3
Q
Muscle fibers are surrounded by the
A
Sarcolemma
4
Q
What is the sarcolemma?
A
Specialized plasma membrane with an outer coat of polysaccharides and collagen
5
Q
Skeletal muscle is the largest site for (2)
A
Blood glucose storage
Lipid oxidation
6
Q
Sarcoplasm contains (4)
A
Mitochondria
Ions
Enzymes
Sarcoplasmic reticulum
7
Q
Where is the main storage site for Ca?
A
Sarcoplasmic reticulum
8
Q
What is calsequesterin?
A
Binds Ca
Maintains Ca in low energy state while in the SR
9
Q
Where is calsequesterin located?
A
In the sarcoplasmic reticulum
10
Q
4 components of myofilaments
A
A band
I band
H band
Z line/disk
11
Q
A band
A
Overlap thick and thin filaments
12
Q
What is a thick filament
A
Myosin
13
Q
What is a thin filament
A
Actin
14
Q
I band
A
Contains actin filaments
15
Q
H band
A
Contains myosin
In the light area of the sarcomere
16
Q
Z line/disk
A
End boundary of the sarcomere
Anchored to actin
17
Q
Myosin contains
A
2 heavy chains
4 light chains
18
Q
Myosin head contains
A
ATPase needed for contraction
19
Q
Actin is made of a double helix of _______ which is made up of _____, _______, and _______
A
F actin
G actin
Troponin
Tropomyosin
20
Q
Troponin’s job is to
A
Shield myosin binding sites on actin
21
Q
Tropomyosin is the
A
Binding domain in actin
22
Q
Troponin I
A
Actin attachment
23
Q
Troponin T
A
Tropomyosin attachment
24
Q
Troponin C
A
Ca binding
25
The motor neuron terminus is ______ and ______
Unmyelinated
| Branches into the muscle cell
26
What is the neuromuscular junction?
Juncture between the motor neuron and muscle tissue
27
What can alpha motor neurons do?
Convert choline into ACh
28
How is the ACh signal deactivated?
Acetrylcholinesterase degrades ACh
29
What are endplate potentials (EPP)?
Sub-threshold membrane depolarizations
30
What is the job of T tubules
Relays the signal from the sarcolemma deep into the muscle cells
31
What is DHPR?
Voltage gated Ca channels
32
Where are DHPRs?
In the T tubule on clusters of ryanodine receptor Ca channels that are embedded in the SR membrane
33
What's RyR?
Ryanodine receptor Ca channels
34
What happens to DHPR as the AP travels down the T tubule?
Undergo conformational change that opens a pore in RyR to allow Ca to flow from the SR lumen to the sarcoplasm
35
Isotonic contractions
Forceful
36
Isometric contractions
Non-forceful
37
Sarcomere shortening and force is generated during an ______ contraction
Isotonic
38
Sarcomere shortening does not occur during an _____ contraction
Isometric
39
How is cross-bridge cycling ended? (2)
Decrease Ca concentrations
| Decreased sarcoplasmic ATP concentrations
40
What is the effect of hypercalcemia?
Induce hpoexcitability because it increases the membrane potential need to open voltage gated Na channels
41
What is the effect of hypocalcemia?
Increase nerve and muscle excitability
42
What is the role of extracellular Ca?
Stabilize membrane Na channels in skeletal muscle and neurons
43
What is the main source of ATP?
Oxidative metabolism of carbs, FA, and protein
44
What is the function of the SERCA pump?
Pump Ca from the sarcoplasm into the SR lumen
45
What is the role of the NCX Exchanger?
Leak channel that helps lower Ca concentrations in the sarcoplasm
46
What are 2 ways the muscle can relax and which is the primary one?
```
SERCA pump (main one)
NCX Exchanger
```
47
What happens if we block the NCX from functioning?
Ca would still be elevated in the sarcoplasm
| Facilitate contractions
48
Concentric contractions
Muscle shortens to displace load
| Force generated by muscle overcomes the load
49
Eccentric contractions
Resistance against contraction is more than contractile force
50
When is the propensity for muscle damage higher? (Concentric or eccentric contraction)
Eccentric
51
Passive tension
Resistance of muscle tissue to stretch due to anatomical properties
52
Active tension
Change in tension during muscle contraction
53
When does active tension peak?
During early phase of isotonic muscle contractions
54
When is the greatest force generated? Why?
During initial phase of muscle contraction from L0
| Optimal overlap of myosin and actin
55
What is a muscle twitch and when does it occur?
Single rapid muscle contraction responding to a single AP
| Before a muscle contraction
56
What is muscle tetany and when does it occur?
Maximum strength of contraction
| When rapid successive twitches fuse
57
What is the orderly recruitment principle?
Smaller motor units (fatigue resistant) are activated first and then the larger motor units (powerful, fatiguable) are activated
58
Type 1 fibers
Slow twitch
Red bc of the vasculature
Sustain activity
59
Type 2 fibers
Fast twitch
| Brief periods of time
60
A single motor unit can innervate
Only ONE type of muscle fiber as it branches in the muscle
61
IGF1 and GH promote
Myofibrillar protein synthesis
62
What are satellite cells
Precursors that provide extra nuclei for growth and repair after an injury
63
What does myostatin do?
Block cell cycle progression of satellite cells
64
What happens if there's a loss of function in myostatin?
Increase muscle mass
65
What is the effect of IGF1 on satellite cells?
Proliferation
66
Resistance training results in
Hypertrophy of mainly type 2 fibers
67
High volume resistance training improves (3):
Insulin sensitivity
Lipid profiles
Hypertension
68
Hypertrophy
Increase diameter of muscle fibers
69
Angiogenesis
Synthesis of vascular tissue
70
Exercise induces an up Regulation in (4):
Mitochondrial number and function
ATP and phosphocreatine content
Enhanced levels of intramuscular glycogen stores
Increase intramuscular triglyceride levels
71
SERCA expression is controlled by
Thyroid hormone
72
Thyroid hormone can upregulate ________ but not increase ______
Rate of contraction and relaxation
| Contractile force
73
What is sarcopenia?
Loss of muscle mass that's associated with age
74
When is peak muscle mass obtained?
20-30s
75
6 effects of glucocorticoids in skeletal muscle:
Dec. proteogenesis
Dec. rate of AA transport
Inhibit IGF1
Stim. Proteolytic signaling (UB-proteosome)
Stim. Myostatin production
Inhib. Myogenin expression (TF needed for satellite cell differentiation)
76
Myokines can modulate
Muscle hypertrophy and myogenesis
77
What is a motor unit?
One motor neuron and the muscle fiber(s) it innervate
78
When are type 1 motor units recruited?
During sustained muscle activity (aerobic)
79
Alpha motor neurons mediate
Voluntary contractile responses of skeletal muscle
80
What is the main function of muscle spindles?
Monitor/allow continuation of muscle contraction
81
Muscle spindles have ________ designed to _______ in _____ and _______
Sensory receptors
Detect changes
Muscle length
Rate of change of length
82
What does GTO stand for? Where are they located? And what's they job?
Golgi Tendon Organs
Musculotendon junction
Relay information to CNS about muscle tension
83
What do GTOs serve as?
Early warning system when tension has suddenly increased
84
Why are GTOs important?
Prevent against muscle tear by having Type In afferents synapse with stimulatory/inhibitory interneurons
85
What is fatigue?
Decrease contractile force due to an increased stimulation frequency or duration
86
Where is smooth muscle usually located?
Wall surrounding hollow organs and vessels
87
Contraction and relaxation of VSM is controlled by (3)
SNS
Hormones
Metabolites
88
Actin filaments in smooth muscle is attached to
Dense bodies, which may be attached to the cell membrane
89
Dense bodies do not contain (5)
```
Sarcomere
Z disks
T tubules
Motor end plate
Troponin
```
90
How does smooth muscle contract? How's does the muscle cell appear?
Sliding filament mechanism
| Crinkled
91
4 extracellular sources of Ca for smooth muscle
Voltage gated Ca channels
Voltage independent Ca channels
Ca induced Ca release
IP3 mediated signal transduction
92
What is calmodulin?
Ca sensor in smooth muscle that binds to Ca to activate myosin light chain kinase
93
In smooth muscle, how does myosin become phosphorylated and what does that mean?
Activation of myosin light chain kinase
| Phosphorylated myosin has high affinity for actin
94
Smooth muscle contraction uses _____ metabolism and can perform ________ duration contractions using ______ metabolic energy
Oxidative
Long
Very little
95
How can smooth muscle can shorten?
Contract on itself in multiple dimensions
| Doesn't alter the overlap btwn myosin and actin (50-75% shortening)
96
Why can smooth muscle stretch more than skeletal, while maintaining active tension?
Loose arrangement of actin and myosin in smooth muscle
97
Higher tension ensures
Sufficient perfusion pressures are maintained
98
Filling an arterioles with blood causes ______ because ______
Profound elevation in pressure
| Tension does NOT drop
