Muscle Physiology Flashcards
Two types of skeletal muscles
Striated
Voluntary
Types of proteins in muscle
Contractile protein
Regulating protein
Structural protein
What are the contractile protein
Actin
Myosin -II
What are the regulating proteins
Tropomyosin
Troponin
1 molecule of tropomyosin covers how many active sites on actin
7 active sites on actin
Series of events occurring for actin-myosin cross bridge formation
Calcium influx Conformational change of troponin Causes troponin to slide Uncovers active sites on actin Actin-myosin cross bridge formation
What are the structural proteins
Actin in
Titin
Desmin
What is the role of actinin proteins
Binds actin to Z-line
What is the role of titin protein
Binds Z line to M line
Forms scaffolding (structural support)
Largest known protein
What does titin mutation cause
Tibilalis muscular dystrophy
What is the role of desmin
Binds Z line to plasma membrane
What is A and I band
A band(dark band)- anisotropic to light Myosin + overlapped actin
I band(light band)-isotopic to light Only actin
What is H and pseudo H zone
H zone - only myosin
Pseudo H zone- only myosin tail (held together like a bunch of golf sticks)
What does a sarcomere comprise of in terms of A and I bands
Sarcomere- 1/2I band + A band + 1/2I band
*Most abundant protein
Collagen
What happens to I band H zone A band during muscle contraction
I band - decreases
H zone- decreases/disappears
A band- unchanged
Name the sarcolemmal proteins
Dystroglycan-sarcoglycan complex
Sarcoglycan Alpha-dystroglycan Beta-dystroglycan Dystrophin Syntropin Sarcospan
Know the diagram (notes)
What does the absence of sarcoglycan cause
Limb girdle dystrophy
Absence of dystrophin causes
Duchene’s
Severe muscular weakness
Reduction in dystrophin causes
Becker’s
What is the function of sarcolemmal proteins
Amplification of force generated by actin and myosin
NMJ
Know diagram
And process
What are the ACh receptors composed of
Ligand gated Na and K channel
When dysfunction of ACh receptors in NMJ causes
Myasthenia gravis
When there is dysfunction of Ca gated channels in NMJ
Lambert eaton syndrome
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
Natural ligand for Ryanodine receptor
Ca
Not ryanodine
What is the excitation contraction coupling agent
Ca
What is the trigger of muscle contraction
The availability of calcium
How long does muscle contraction continue till
Till calcium is available
How is sarcoplasmic Ca removed
SERCA
Primary active transport for Ca
If SERCA is absent what happens to the duration of muscle contraction
It increases
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)
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)
Why does rigor mortis happen
Ca channel becomes leaky
Release
Actin-myosin bridge formation
But no ATP there for detachment (cuz person is dead)
Number of ATP used in 1 cross bridge cycle
ONE
Cross-bridge cycling happens till
a) ATP is available
b) Ca is available
b)ca is available
Types of muscle fibres
Type 1- slow
Type 2- fast
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
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
What is a motor unit
Single Aalpha motor neuron and all muscle fibres it supplies (only one type of muscle fibres)
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
Muscle of back have how many muscle fibres per unit
Around 600 muscle fibres/muscle unit
Muscle unit used for standing
S (slow) motor units of calf muscles
Type I
Muscle unit used for walking
S + FR
(Slow and fast and resistant to fatigue)
(FR muscle fibre - type IIa-fast oxidative glycolytic(FOG))
Muscle unit used in running
S+FR+FF(fast and fatiguable)
FF -muscle fibre -FG (fast and glycolytic) type IIb
Types of muscle contraction
Isotonic
Isometric
Know the characteristics and eg (it’s easy)
Mechanism of isometric contraction
Contractile component shortens and elastic component stretches (therefore same length)
What are the elastic components
Titin
Elastic fibres in tendon
Mechanism of isotonic muscle contraction
Shortening of contractile component
Folding of SEC
(Therefore decrease in total length)
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
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
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)
What happens in dilated cardiomyopathy (length tension relationship)
Initial length is beyond physiological limit
Decreased tension generated
Failure
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
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
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
Tetanus definition
State of sustained contraction
What is incomplete tetanus
Brief period of relaxation between 2 successive contraction
What has refractory period
Electrical or contractile activity
Electrical activity
What is tetanizing frequency
Minimum frequency of stimulation at which muscle is tetanized = 1/C.P(sec)
CP-contractile period
Beneficial effect/treppe/staircase effect seen in
Incomplete tetanus
If frequency of stimulation is less than tetanizing frequency
(Due to accumulation of ca )
Duration of exercise for ATP stores energy
1-3 seconds
Duration of exercise from ATP from creating phosphate for exercise
7-8 sec
What is phosphogen system and the duration of exercise from the energy
ATP stores
ATP from creating phosphate
8-10sec
Duration of exercise from energy from ATP glycolytic metabolism
1-1.5 min
Duration of exercise from energy from ATP from oxidative metabolism
More than 1.5 min
Exercise done using phosphogen system (major source)
100 m race Diving Long jump High jump Javelin throw Discus throw
Exercise that can be done with phosphogen and glycolytic metabolism
(Major source)
Duration >10sec <30sec
200m race
100m race
Glycolytic metabolism major source of energy in what exercise
400m run
200 m swim
ATP form oxidative metabolism major source of energy in what exercise
5km run
Marathon
Boxing
Rowing
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
