Muscle Damage and Repair

examples of external trauma that can cause muscle damage

examples of external trauma that can cause muscle damage

laceration, crush, contusion, burn

death of muscle tissue where contents are released into bloodstream

rhabdomyolosis

main concern with rhabdomyolosis

renal failure

disease that causes increased presence of immune cells in the muscle tissue, leads to fibrosis

polymyositis

disease caused by loss of dystrophin protein, results in a loss of link b/w muscle layers and shearing

muscular dystrophy

what is pseudohypertrophy?

Muscle replaced by scar tissue

What are some causes of ischemia?

vascular disease, compression or occlusion of vessels

what is the progression of pain due to compartment syndrome?

pain with activity, pain at rest, necrosis

what causes compartment syndrome?

fascia that compresses vessels

pattern seen in muslces due to unaccustomed exercise especially eccentric contractions

z-line streaming

what causes z-line streaming?

damage due to load and inflammatory response

what fiber type sees the greatest amounts of z-line streaming

type II

what pattern is often seen in force loss due to contraction-induced damage

bimodal force loss (24-48 hr duration)

According to the repeated bout effect: damage and pain following a second bout of exercise is ________ significant compared to the first

less

what are the features of contraction-induced damage

prolonged force loss, creatine kinase in bloodstream, DOMS, repeated bout effect

What are some causes of muscle damage?

trauma, disease, ischemia, tears, exercise

what is the process of muscle repair by regeneration (4 steps)

digestion of damaged components, proliferation of satellite cells, fusion into myotubes, synthesis of contractile proteins

what triggers the proliferation of satellite cells?

loss of contact with sarcolemma, release of mitogenic factors

what factors influence the originization of myotubes

presence of basal lamina, mechanical stresses (optimal loading)

what nucleus location serves as a marker of regeneration?

the center

causes of fibrosis

disease, repeated trauma, prolonged inflammation

what causes the production of scar tissue in fibrosis?

excessive or prolonged activation of fibroblasts→ overproduction of ECM components

histology of muscle with fibrosis

less muscle fibers and increased scar tissue

what are the 5 P’s used in screening for compartment syndrome?

pain, palor, pulselessness, paresthesia, paralysis

what is the typical treatment for compartment syndrome?

faciotomy