Physiology Of Muscle Contraction Flashcards
In skeletal 4 Ca bind to?
Troponin C, but in heart 3 Ca, changes conformation, shuts off Tn1 tropomyosin- troponin leaves F-actin groove unmasks the myosin binding site on actin
Troponin I is a marker for?
Total muscle breakdown
Cardiac TnI is marker for?
Myocardial infarct
Macro molecular contraction?
Contraction depends on myosin head binding to think actin filaments at specific binding sites.
Otherwise blocked by tropomysoin
Cross bridge cycle?
- To allow myosin head to let go, release ADP, require ATP to allow myosin to let go of actin
- Myosin head cleaves ATP
- Myosin binds actin, when moved tropomysoin out of way (ca was present)
- Power stroke
What is rigor mortis?
ATP is needed to pump ca in sarcoplasmic reticulum.
ATP deleted
Myosin stuck to actin,
Rigor mortis ends when muscle tissue degrades after 3 days
How do you store ATP?
Creatinine is stored in muscle after phosphorylation
How to get energy from. Muscles?
Creatine phosphate (in mitochondria) gives a phosphate group to ADP.
Creatine phospho kinase does what?
Adds phosphate to creatine
Phosphokinase is a marker of?
Muscle destruction
Creatinine is?
Breakdown product of creatine, marker for kidney function
Depolarisation allows influx of calcium?
Active nicotine cells acetylcholine receptor, net inward current.
Causing depolarisation spread via T-Tubules
Local action potentials trigger Ca2+ efflux from terminal cisternae
Across membrane of sarcoplasmic reticulum
into the fibre cytoplasm
SERCA does what?
Puts ca back in the SR
Ryanodine receptor does what?
Releases ca from SR, triggered by voltage sensor on ca channel
Frequent APs cause complete tetany because?
Insufficient Ca resequestration so summation of contraction
Slow twitch are?
Type 1 “red” oxidative small diameter
High myoglobin, many mitochondria
Fast twitch have?
Type 2 white
Non oxidative wide diameter
Lower myoglobin
Energy requires from glycolysis
Which muscle fibres are fatigue resistance?
Slow
Soleus muscle has composition?
80% type slow
20% type IIA
Vastus lateralis for running has composition?
Mixture of type I, IIA, IIX
Long distance runner have?
Type 1 predominantly
In type I what type of fuel as storage?
Triglycerides
In Type II fibres the fuel for storage?
Creatine phosphate
Glycogen
Motor unit is?
A single alpha motor neuron and muscle fibres it innervates
Isometric?
Generates variable force while length of muscle remains unchanged
Isotonic?
Generates a constant force while the length of muscle changes
Eccentric contraction?
Force during muscle elongation
Size principle?
as the initial isometric contraction occurs:
more and more motor units are recruited starting with smaller ones and progressively adding larger ones
Lower motor neuron disease?
Weakness
Muscle atrophy
Upper motor neurone disease?
Spasticity, hypertonia
Lack of patellar reflex is called?
Westphals sign
Muscle spindle consists of how many intrafusal fibres?
3-12
Sensors from muscle spindle are called?
Type 1a and Type 2
Tendon reflex aim?
Protection from overloading
Tendon reflex has how many synapses?
2
Eccentric and concentric contraction?
Eccentric- force during muscle elongation
Concentric- force during contraction
Size principle?
Always start with small motor unit, as its going through feedback mechanisms, recruit bigger motor units to generate force
Absence of Westphalia sign means there is?
Receptor damage
Femoral nerve damage
Peripheral nerve disease
