Muscle Phys - Pertubations

Question 1

Effects of exercise on muscle

Answer 1

Causes mechanical stress, synthesis of myofibrils, gain nuclei, capacity for fiber repair/generation, individual fibers thicken. New nuclei are donated by progenitor “satellite cells” that proliferate in response to mechanical stress

Question 2

Effects of sedation on muscle

Answer 2

Atrophy, degradation of contractile proteins to recover building blocks
Utilized for free amino acids, ventilation of lungs is impaired, recovery from stress or pathogens is impaired, increased morbidity

Question 3

Sequence of events promoting contraction

Answer 3

Motor cortex -> neurotransmission -> motor neuron release -> acetylcholine -> binding -> nicotinic ACh receptor + muscle fiber cell = depolarization
Sarcolemma Ca channels (DHPR) + SR channels (RyR) = Ca release -> ca in sarcoplasm -> binding -> Ca+troponin -> conformational change in thin filaments -> cross bridge formation/sliding = force

Question 4

Sequence of events promoting relaxation of muscle

Answer 4

Cross bridge formation/sliding/force -> ca+troponin = dissociation -> ca in sarcoplasm = reuptake via SERCA -> DHPR + RyR = repolarization -> muscle fiber/nicotinic ACh receptor -> dissociation -> acetylcholine = hydrolysis by synaptic ACh esterace = reuptake