regulation of muscle contraction Flashcards
- excitation-contracton coupling:
1- Action potential
propagates along the —-
2- causes the release of — from terminal cistern so that sarcoplasmic
Ca++ concentration — from — to —
3- —- binds Ca++ causing
conformational changes which
allow —– formation
with actin and release of —-
and—- from the myosin
ATPase.
4-Further conformational
changes move the
crossbridges thereby
pulling the actin filaments
towards the — of the —
5- —– binds
ATP causing dissociation
of the crossbridges,
—- of ATP and
return to the “cocked”
position for further cycles
6 - Relaxation occurs
when the sarcoplasmic
Ca++ concentration
returns to—- by
—- of Ca++
back into the the
sarcoplasmic reticulum
where it is bound to
—
- sacrolemma and T cells
- ca++
- increase
- 10-7 to 10-5 molar
- troponine
- crossbridge
- adp and phosphate
- centre of the a band
- myosin atpase
- hydrolysis
- normal
- active transport
- calsequestrin
The dihydropyridine receptor (DHPR) acts as a —- that
causes the ryanodine receptor (RYR) in the SR to open its —-
- voltage sensor
- ca+2 channels
( check slide 6)
—– Stiffening of body muscles after death
- —- is required for detachment of myosin cross bridge from actin
- Following death no more —- is produced
- Begins —- after death
- Gradually decreases days
later as —-
- rigor mortis
- atp
- atp
- 3-4 hours
- protein degrade
energy expended during —-
1- —- heads are bound to atp
2- —— hydrolysis atp to adp+pi = high energy ready state
3- — binding to — releases — attachment to actin
- contraction (adp+pi released )
- myosin ATPase
- myosin
- atp
- cross bridge
-There is a small store of —- and 5-10 times more —– intracellularly
- Creatine phosphate + ADP -> —-
- The enzyme is —-
- —– can increase muscle creatine phosphate levels
- The ATP comes from —-
metabolism of mainly glycogen, glucose and fatty acids when oxygen supply is adequate, and from anaerobic glycolysis to lactic acid when there is inadequate
oxygen
- atp
- creatine phosphate
- creatine + atp
- creatine kinase
- dietary creatine
- aerobic oxidative
-Skeletal muscles require—- for multiple stages of contraction such as:
* ATP required for —- to release from actin
* —- uses ATP to transport Ca2+ back into sarcoplasmic reticulum
energy supply can be from:
1- —- for immediate source of energy in less than one min
2- —: for endurance type exercise
3- —- : for high intensity excursise
- atp
- myosin head
- Ca2+ ATPase
1- creatine phosphate: - Fast
- Resting muscle CP levels =
5xATP levels - CP stores replenished during
rest - Immediate source of
energy (<1 min)
2- oxidative ohsophralion :
~32 ATP per glucose
O2 + nutrients required - aerobic
Relatively slow due to large
number of reactions
Very efficient/sustainable
Endurance-type exercise
3- glycolysis :
2 ATP per glucose
No O2 required - anaerobic
Fast
Produces lactic acid
Inefficient/unsustainable
High intensity exercise
muscle fiber types are characterised based on — and —-
- type 1:
- type 2:
- type 3:
- speed of contraction and atp production
-– Type I: Slow-oxidative (small diameter)
– Type IIa: Fast-oxidative (intermediate diameter)
– Type IIx: Fast-glycolytic (large diameter)
- fast —> — myosin ATPase activity
- fast twitch =
- slow twitch =
- oxidative phosphorylationproduces atp in — fibers and is more efficient than —
- glycolysis generates atp via aerobic glycolysis and has – fibers its inefficient method with also produces lactic acid
- higher
- 15-40
- 50-100
- red
- more efficient than glycolysis bc more resistant to fatigue
- white
- slow muscles are adapted for — metabolism
- fast muscles are adapted for — metabolism
- slow muscles are – due to mitochondria , myoglobin and vascularity
- fast muscles are – bc they lack all of the above
- aerobic
- anaerobic
- red
- white
- ibidivuials cells are either —-
- whole muscle consists of —
- whole muscles are described as fast or slow if the – of its cells are fast or slow respectively
- slow or fast
- fast and slow
- majority
-training has — effect on fast or slow fibre numbers
- training regimens — alter the fibre type or the — of myosin isoforms
- elite sprinters have high number of —
- elite endurance athlete have Hugh number of —
- little
- cant
- expression
- fast fibers
- slow fibres
muscle fibers adapt to demand :
1- training can improve —- which increases —– of mitochidnira , this is more —- to fatigue
2- change in muscle fibre —-
- the size of the muscle is — by short high intensity anerobic exercise ( weight lifting )
- affects —-
3- —– which is the muscle decreases in mass if not routinly used
- oxidative capacity
- increase blood supply/number
- more resistant
- diameter
- increased( hypertrophy)
- fast-glycolytic fibres
- atrophy
—— atrophy also occurs in peripheral neuropathies, disuse (bedrest,spaceflight, immobilization), myasthenia gravis etc
- Mainly type — atrophy with Duchenne muscular dystrophy and ageing
(sarcopaenia)
- type ii hypertrophy occurs w/ —-
-Pseudohypertrophy in calf muscles in Duchenne muscular —- (“false
enlargement,” because the muscle tissue is abnormal.)
- type I and ii
- type ii
- weight training
- dystrophy
neuromuscular diseases include:
- Neuropathy (disease affecting nerves) in the central or
peripheral nervous system or both (peripheral nerves, e.g.
motor neuron disease; multiple sclerosis etc.) - Junctionopathy (Neuromuscular junctions, e.g.
myasthenia gravis) - Myopathy (disease affecting muscle, e.g. muscular
dystrophies)
-during — contraction the tension increase until it — the weight to be lifted
- then muscle — ad the tension stays —
- isotonic
- equals
- shortens
- constant ( isotonic = same tension )
