Muscle Physiology
How They Work
Muscle Fibers
Muscles are made of many individual
cells called fibers
The Fascia connects the individual
fibers to form a muscle and it
separates muscles from each other.
Muscles have 3 layers of C.T.
Epimysium: outermost layer that
surrounds the whole muscle
Perimysium: Surrounds and separates
the fascicles
Endomysium: surrounds each
individual muscle fiber
Muscle fiber membrane:
The plasma membrane of a muscle
fiber is called the sarcolemma
The cytoplasm is called the
sarcoplasm
Inside the sarcolemma
The many parallel fibers inside the
muscle cell are called myofibrils.
Each myofibril is made of protein
filaments called myofilaments.
The thin filaments are actin.
The thick filaments are called myosin.
What is a sarcomere?
Actin and Myosin filaments are
arranged in an overlapping pattern of
light ("I" bands) and dark ("A" bands).
In the middle of each "I" band is a line
called a "Z" line.
The section of a myofibril from one Zline to the next Z-line is the
SARCOMERE.
The
arrangement of
the sarcomeres
produces the
familiar
striations of
skeletal muscle.