Skeletal Muscle Tissue Flashcards
What are myoglobin?
Particular type of protein in the vessels of the muscle.
Able to bind oxygen.
Gives muscles its red appearance.
What are the features of skeletal muscle under LM?
Long and cylindrical.
Diameter from 10-100microns
Each fusion cell has its own nucleus so appears as multinucleated cells.
Nuclei are localised under the sarcolemma (PM).
Has basal lamina surrounding each fiber.
Cross-striation
What are muscle fibers derived from?
Derived from fusion of several cells - myoblast. They will fuse to initially form myotubes, which will then grow and form a myofiber.
Describe the structure of a muscle fiber.
Inside the cells it can be observed that the cytoplasm has small points called myofibrils.
These are organised inside the cytoplasm to occupy the whole space. They are a long structure along the whole length of the cell.
Describe the striation of muscle fibers.
The striation is due to an alternation of structures typical of the myofibrils. I band and A bands can be observed, the I bands are lighter and A bands are darker.
Each myofibril is striated regularly so that they represent one band together with no cross organisation.
Describe the structure of a sarcomere.
This organisation mainly comes from actin and myosin. Myosin forms the thick filament while actin forms the thin filaments. These are organised specifically to form the sarcomere.
Actin filaments will start from the Z line and don’t completely reach the M line to create a H zone. The Z line has zig-zag shape which is due to the presence of alpha - actinin protein holding the structure together.
What subunits can troponin be divided into?
I,C & T
