Muscle Flashcards
What types of muscle are there?
3 main types:
Skeletal muscle - Striated, multinucleated and voluntary
Cardiac Muscle - Striates, mononucleated and involuntary
Smooth (visceral muscle) - non-striated, mononucleated, spindle-shaped and involuntary
What is the anatomy of Skeletal Muscle?
Skeletal muscle - bundle of muscle fibres
Muscle fibres - Multinucleated cells containing myofibrils
Myofibrils - Highly ordered assemblies of thick myosin and thin actin filament
Draw the structure of a myofibril.
See Diagram
What is the Sliding Filament theory?
The sarcomeres contract
Actin filaments move over myosin filaments
There is no change in the A band
What type of muscle fibres are there?
Type I - Slow twitch - Long endurance
- oxidative, fatigue resistant, slow contraction time, low force production, used for anaerobic activities
Type II - Fast twitch - short fast bursts
Type IIa - Oxidative/glycolytic, fatigue resitant, fast contraction time, high force production, small, red - long-term anaerobic
Type IIb - Glycolytic, fatigue sensitive, very fast contraction time, very high force production, large, white - short-term anaerobic
Important sites to maintain integrity and function.
1) Muscle cell plasma membrane (sarcolemma)
2) Myotendinous Junction
- Junction between tendon and muscle fiber digit-like extensions
- site of force transmission of muscle to tendon/bone
3) Neuromuscular Junction
- Between motorneuron and muscle fiber
- Site of action potential initiation
- ACh (AChR) - Na+ out K+ in
Describe the basement membrane.
Surrounds each muscle fiber
Tightly associated with sarcollemma
Inbetween fibers is Endomyium (connective tissue)
Composed of Perlecan, Collagen IV, Laminin and Nidogen
- Forms sheet
Describe Muscle Stem Cells.
Satellite cells
Outside Sarcolemma, inside basement membrane
Regulates Cell regeneration
See diagram
