Regulation of muscle contraction and energy sources Flashcards
excitation-contraction coupling
AP prpogates along sarcolemma and T system
release Ca2+ from terminal cisternae to sarcoplasmic reticulum Ca2+ conc increases from 10^-7 to 10^-5
skeletal muscle contraction mechanism
somatic motor neuron release ACh at nm juntion
influx of Na+ and efflux of K+ ions start AP
AP in t tubules alters shape of dihydropyridine receptor
DHP receptor opens Ca2+ releasee channels in SR aalows Ca2+ enter cytoplasm
Ca2+ binds to troponin tropomyosin moves from attachment site of actin tropomyosin
myosin head execute power stroke
actin filament slide to centre of sarcomere
skeletal muscle mechanism of actin and myosin
free myosin bound to ATP which is hydrolysed by myosin ATPase to ADP and Pi
ADP and phosphate is release from myosin ATPase as troponin binds to Ca2+
myosin pulls actin to middle of sarcomere - myosinATPase binds to ATP - dissociate crossbridges
leads to hydrolysis of ATP back to ADP and P
When does relaxation typically occur
when sarcoplasma Ca2+ conc returns to normal by active transport to sarcoplasmic reticulum bound to calsequestrin
what is malignant hyperthermia, its causes and its symptoms
rare disorder in which anaesthesia causes, if untreated, a rapid rise in body temperature, muscle rigidity, muscle damage and death
cause of malignant hyperthermia
by an abnormal ryanodine receptor reaction
with agents used in anaesthesia resulting in excessive
calcium entering the sarcoplasm
treatment of dantrolene
a muscle relaxant that blocks
the ryanodine receptor
energy for contraction
small ATP
5-10 times more creatine phosphate
what does ADP and creatine phosphate make
creatine and ATP
enzyme for creatine phosphate
creatine kinase
purpose of creatine in diet
increase muscle creatine phosphate levels
ATP is a product of
aerobic oxidative metabolism of mainly glycogen, glucose and fatty acids with enough oxygen
anaerobic glycolysis to lactic acid when there is limited oxygen
how long is glycogen stored for and where
in muscle and liver for 2-4 hours
oxidative metabolism of what food groups lasts for
Carbohydrates
Fats
Proteins
hours
how is ATP used in creatine phosphate
• 1 ATP per CP • Fast • Resting muscle CP levels = 5xATP levels • CP stores replenished during rest • Immediate source of energy (<1 min)
