Muscle Plasticity Flashcards
1. Describe how muscle fibre types are distributed within and between muscles and individuals. 2. Explain adaptations due to: growth, exercise, nutrition and ageing. 3. Describe the basic regulatory processes behind skeletal muscle adaptation
How should normal muscle appear when stained for myosin ATPase?
Should have a patchwork appearance, even with training muscle fibre types will look like this although one type may occupy a greater proportion. An accumulation of one type in one particular area may indicate a myopathy.
How are muscle fibre types distributed within a muscle?
Deep postural (closer to bone) has more slow oxidative fibres?
What can be used as a marker for mitochondria?
Succinate dehydrogenase
Why would growth affect muscle fibres, and how might they change?
- Animal get heavier
- Animal changes shape/gets taller => longer muscles.
- Lifestyle changes (need/no need to locomote)
Muscles will hypertrophy, architecture and fibre type may also need to change.
What is the effect of increased use on muscle?
Hypertrophy, becomes slow oxidative unless specific strength (resistance) training is used.
What is the effect of stretching a muscle and where does this change occur?
Addition of sarcomeres at the myotendinous junction. In younger animals the tendon can also lengthen. Slow sarcomeres are always added so further training may be needed.
Which fibre type do muscles naturally revert to?
Type 2
How is muscle growth regulated and what cells are involved?
Sensor proteins detect signals resulting in signalling cascades and transcription/translation. Satellite cells with stem cell like properties form myotubes>myofibrils.
Which nutrients are important?
Protein, glycogen and triglycerides.
What 4 things that happen to muscle are associated with ageing?
- Reduction in satellite cells and their proliferative capacity.
- Decreased muscle mass and efficiency (possibly due to reduction in no. of groth factors)
- Decreased blood supply.
- Increased fibrous connective tissue which influence the muscles properties.
