Muscle Physiology Flashcards
(72 cards)
1
Q
Two types of skeletal muscles
A
Striated
Voluntary
2
Q
Types of proteins in muscle
A
Contractile protein
Regulating protein
Structural protein
3
Q
What are the contractile protein
A
Actin
Myosin -II
4
Q
What are the regulating proteins
A
Tropomyosin
Troponin
5
Q
1 molecule of tropomyosin covers how many active sites on actin
A
7 active sites on actin
6
Q
Series of events occurring for actin-myosin cross bridge formation
A
Calcium influx Conformational change of troponin Causes troponin to slide Uncovers active sites on actin Actin-myosin cross bridge formation
7
Q
What are the structural proteins
A
Actin in
Titin
Desmin
8
Q
What is the role of actinin proteins
A
Binds actin to Z-line
9
Q
What is the role of titin protein
A
Binds Z line to M line
Forms scaffolding (structural support)
Largest known protein
10
Q
What does titin mutation cause
A
Tibilalis muscular dystrophy
11
Q
What is the role of desmin
A
Binds Z line to plasma membrane
12
Q
What is A and I band
A
A band(dark band)- anisotropic to light Myosin + overlapped actin
I band(light band)-isotopic to light Only actin
13
Q
What is H and pseudo H zone
A
H zone - only myosin
Pseudo H zone- only myosin tail (held together like a bunch of golf sticks)
14
Q
What does a sarcomere comprise of in terms of A and I bands
A
Sarcomere- 1/2I band + A band + 1/2I band
15
Q
*Most abundant protein
A
Collagen
16
Q
What happens to I band H zone A band during muscle contraction
A
I band - decreases
H zone- decreases/disappears
A band- unchanged
17
Q
Name the sarcolemmal proteins
A
Dystroglycan-sarcoglycan complex
Sarcoglycan Alpha-dystroglycan Beta-dystroglycan Dystrophin Syntropin Sarcospan
Know the diagram (notes)
18
Q
What does the absence of sarcoglycan cause
A
Limb girdle dystrophy
19
Q
Absence of dystrophin causes
A
Duchene’s
Severe muscular weakness
20
Q
Reduction in dystrophin causes
A
Becker’s
21
Q
What is the function of sarcolemmal proteins
A
Amplification of force generated by actin and myosin
22
Q
NMJ
A
Know diagram
And process
23
Q
What are the ACh receptors composed of
A
Ligand gated Na and K channel
24
Q
When dysfunction of ACh receptors in NMJ causes
A
Myasthenia gravis
25
When there is dysfunction of Ca gated channels in NMJ
Lambert eaton syndrome
26
Sarcotubular system
| Types of tubules and receptors present on them
T-tubule
Invagination of sarcolemma
Dihydropyridine receptor (voltage sensor)
L-tubule
Sarcoplasmic reticulum
Ryanodine receptor (ligand gated Ca channel)
Know the process
27
Natural ligand for Ryanodine receptor
Ca
| Not ryanodine
28
What is the excitation contraction coupling agent
Ca
29
What is the trigger of muscle contraction
The availability of calcium
30
How long does muscle contraction continue till
Till calcium is available
31
How is sarcoplasmic Ca removed
SERCA
| Primary active transport for Ca
32
If SERCA is absent what happens to the duration of muscle contraction
It increases
33
At rest what state is myosin in
| Actin-myosin cross bridge formation and cross bridge cycling
At rest
Myosin head - high energy and high affinity state
(Cocked state)
34
Steps of cross bridge formation
1.power stroke
2.attachment of ATP on myosin head
Conformational change
3.detachment of myosin head
4.hydrolysis of ATP to ADP,Pi,energy
Recocking of myosin head
5.back to myosin at rest (high energy high affinity)
35
Why does rigor mortis happen
Ca channel becomes leaky
Release
Actin-myosin bridge formation
But no ATP there for detachment (cuz person is dead)
36
Number of ATP used in 1 cross bridge cycle
ONE
37
Cross-bridge cycling happens till
a) ATP is available
b) Ca is available
b)ca is available
38
Types of muscle fibres
Type 1- slow
| Type 2- fast
39
Differences between type 1 and type 2
```
Type 1
S-slow,small
O-oxidative
R-red
R
Y
Long twitch duration
More mitochondria
More myoglobin
Delayed fatiguability
Slow sustained contraction
```
```
Type 2
Fast,large
Glycolytic
White
Early fatigueuability
Brief powerful contraction
```
40
During graded muscle contraction which of the following is true
a) fast muscle fibres are recruited before slow
b) large “. “ small
c) stronger,weaker
d) well perfused,poorly perfused
d) well perfused,poorly perfused
41
What is a motor unit
Single Aalpha motor neuron and all muscle fibres it supplies (only one type of muscle fibres)
42
Around how many muscle fibres needed in each motor unit for extra ocular muscles
Very fine movement
| Therefore 5-6 (<10) muscle fibres each fibre unit
43
Muscle of back have how many muscle fibres per unit
Around 600 muscle fibres/muscle unit
44
Muscle unit used for standing
S (slow) motor units of calf muscles
| Type I
45
Muscle unit used for walking
S + FR
(Slow and fast and resistant to fatigue)
(FR muscle fibre - type IIa-fast oxidative glycolytic(FOG))
46
Muscle unit used in running
S+FR+FF(fast and fatiguable)
FF -muscle fibre -FG (fast and glycolytic) type IIb
47
Types of muscle contraction
Isotonic
Isometric
Know the characteristics and eg (it’s easy)
48
Mechanism of isometric contraction
Contractile component shortens and elastic component stretches (therefore same length)
49
What are the elastic components
Titin
| Elastic fibres in tendon
50
Mechanism of isotonic muscle contraction
Shortening of contractile component
Folding of SEC
(Therefore decrease in total length)
51
Types of heat generated in isotonic and isometric
Resting heat
Initial heat (activation heat,shortening heat)
Recovery heat
Relaxation heat
All given out in both contractions
Relaxation heat only given out in isotonic
52
Frank starling’s law (length-tension relationship)
During isometric muscle contraction,more the initial length,more is the total and active tension generated but upto physiological limit beyond which further increase in initial length decreased tension is generated
I know it’s long but pls pls
Also know the graph
53
How is the length-tension relationship applicable to ventricular muscle fibres
Increase venous return
Increase filling
Increase EDV
increase initial length of ventricular muscle fibres (increase SV and CO)
Increase tension generated (upto physiological limits)
54
What happens in dilated cardiomyopathy (length tension relationship)
Initial length is beyond physiological limit
Decreased tension generated
Failure
55
What is optimum length (length tension relationship)
Optimum length is that initial length at which if muscle contracts isometrically,total and active tension generated is maximum
56
What does optimum length correspond to in terms sid actin myosin
Sarcomere length 2-2.2 micrometer
Max overlap between actin and myosin
Max number of actin myosin cross bridges
OL aka resting length
57
Preloaded muscle contraction vs after loaded muscle contraction
contraction period,relaxation period,height of contraction and work done is more in preloaded contraction compared to afterloaded contraction
Only latent period is less in preloaded muscle contraction
58
Tetanus definition
State of sustained contraction
59
What is incomplete tetanus
Brief period of relaxation between 2 successive contraction
60
What has refractory period
| Electrical or contractile activity
Electrical activity
61
What is tetanizing frequency
Minimum frequency of stimulation at which muscle is tetanized = 1/C.P(sec)
CP-contractile period
62
Beneficial effect/treppe/staircase effect seen in
Incomplete tetanus
If frequency of stimulation is less than tetanizing frequency
(Due to accumulation of ca )
63
Duration of exercise for ATP stores energy
1-3 seconds
64
Duration of exercise from ATP from creating phosphate for exercise
7-8 sec
65
What is phosphogen system and the duration of exercise from the energy
ATP stores
ATP from creating phosphate
8-10sec
66
Duration of exercise from energy from ATP glycolytic metabolism
1-1.5 min
67
Duration of exercise from energy from ATP from oxidative metabolism
More than 1.5 min
68
Exercise done using phosphogen system (major source)
```
100 m race
Diving
Long jump
High jump
Javelin throw
Discus throw
```
69
Exercise that can be done with phosphogen and glycolytic metabolism
(Major source)
Duration >10sec <30sec
200m race
100m race
70
Glycolytic metabolism major source of energy in what exercise
400m run
| 200 m swim
71
ATP form oxidative metabolism major source of energy in what exercise
5km run
Marathon
Boxing
Rowing
72
What is endurance training and strength training do
Endurance training- increase stamina (running,jogging,swimming)
Increase oxidative capacity
Strength training- increase strength/power
(Weight training)
Increase glycolytic capacity
