Sarcomere Structure Flashcards
What are myoblasts ?
Embryonic mesoderm cells
What is a myotube ?
Immature multinucleate muscle fibre
Briefly describe the development of muscle
Myoblasts undergo cell division to increase in number and enlarge.
Several myoblasts fuse together to form a myotube.
Myotube matures into skeletal muscle fibre.
Outline the steps involved in muscle contraction
Neuronal stimulus
Transfer of signal to muscle cell
Relay of signal inside the cell
Conversion of electrical signal to mechanical signal
Muscle contraction
What is the sarcomere ?
The sarcomere is the main contractile unit of muscle fiber in the skeletal muscle.
Can be known as the structure between 2 Z discs.
Thick filaments
Myosin
Thin filaments
Actin
What is each sarcomere composed of ?
Myofilaments containing actin and myosin.
Bundles of myofilaments are called myofibrils.
A bands
Dark bands that contain whole thick filaments (myosin)
What does the outer edge of the A band contain ?
Thick and Thin filaments which overlap.
Thick - myosin
Thin - actin
I bands
Light bands that contain only the thin filaments (actin) and are located between the two thick filaments.
Z disc
The area that traverses the I bands and marks the point of the connection between the two neighboring actin filaments.
M line
Marks the middle of the sarcomere and contains the protein called myomesin.
H zone
The H zone contains only myosin.
Name some supporting proteins
Alpha-Actinin
Titin
Nebulin
Dystrophin
At muscle rest describe the bands of the sarcomere
The A and I bands are similar widths