Muscle anatomy is very complex. Explore the anatomy of a skeletal muscle using your book and on-line resources. Describe how all these parts work together to produce movement.

A Skeletal muscle is an organ of the muscular system. Skeletal muscles are made up of skeletal muscle tissue, nervous tissue, blood and connective tissue. A Skeletal muscle fiber is a single cell that contracts in response to stimulation and then relaxes when the stimulation ends. The skeletal muscle fibers are thin elongated cylinders with rounded ends. In the muscle fibers there are myofibrils proteins myosin and actin, sarcomere, sarcoplasmic reticulum and transverse tubules.

Nervous tissue is responsible for sensory reception and conduction of nerve impulses. Nervous tissue receives impulses from the brain to tell the muscles to contract.

Blood transport substance and helps to maintain internal environment.It is transported throughout the body within a closed system of blood vessels and heart chambers.

Tendon(aponeurosis)=All fibrous connective tissue extends beyond the muscle fibers.
A muscle fiber is also known as a myofiber.

Fascia= Layer of connective tissue that encloses a muscle.

Epimysium= Fibrous connective tissue that binds bundles of fibers together.

Perimysium= Fibrous connective tissue that covers fasicles.

Fasicles= Bundles of muscle fibers.

Endomysium= Fibrous connective tissue that covers the muscle fibers.

Muscle fiber= Thin, cylinder-shaped and can extend the whole length of a muscle,
-has nuclei
-has cell membrane called sarcolemma

T Tubules- set of membranous channels that extend inward as invaginations from the fiber's membrane and passes all the way through the fiber
-each tubule opens outside of the muscle fiber
-each tubule lies between two enlarged portions of the sacroplasmic reticulum
-the tubules and the sarcoplasmic reticulum activate the muscle contractions

A Band- are the dark bands which are composed of myosin filaments overlapping with thin actin filaments

I Band- are light bands and are composed of thin actin filaments directly to structures called z lines

A. Parts of muscle fiber
-Sarcoplasmic reticulum: Special type of endoplasmic reticulum that surrounds muscle fiber.
-Myofibrils: A bundle of myofilaments running the length of a muscle fiber.
-Filaments: Causes striation patterns.
-Myosin
-Actin
Skeletal_Muscles-1.gif
This is a cite for an animation of a skeletal muscle
http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html

What effect do steroids have on muscle?

external image bodybuilder.bmp


Steroid may improve performance in short term
Steroids hasten adulthood, stunting growth and causing early baldness