Muscle Injury & Healing Flashcards
Satellite cells
Muscle stem cell
Muscle progenitor cell
Quiescence
Quiet state of inactivity
Proliferation
Cell division to make more cells
Symmetric division
Stem cells make more stem cells
Self renew
Asymmetric division
One stem cell differentiates into a specialized cell
Regeneration
Damage to a tissue followed by recovery of structure and function
Cytokine/chemokine
Protein released by one cell that is detected by another cell
Common types of muscle injury
Exercise induced injury, strain or pull, laceration or contusion, volumetric muscle loss
Exercise induced injury
During eccentric contraction muscle experiences high forces that damage sarcomeres
Damage can be repaired by myofiber alone or with assistance of satellite cells
Result is delayed onset muscle soreness or eventually hypertrophy
Strain or pull
Following eccentric contraction, high velocity fall, or joint dislocation
Myofiber are completely torn typically through one or more fascicles
Cannot be repaired by myofiber alone, required satellite cells to bridge damage
Laceration or contusion
Common in contact sports and vehicular accidents
Something hits your muscle really hard
Sharp - cuts through myofiber and cause laceration
Dull - crushes myofiber and cause contusion
Fibrotic scarring is common
Volumetric muscle loss
Most frequently in military personnel, can also happen in vehicular accidents
Large portions of the muscle volume are destroyed
Satellite cells cannot overcome this degree of damage
Muscle is irretrievably lost and replaced with fibrotic scar
Quiescent satellite cell to fusion with injured muscle
Satellite cells activate and proliferate (leave enough for future repairs)
Fuse to damaged fiber
Regenerated myofiber with central nuclei
Nuclei move to peripheral site in myofiber
