Muscular System X

The Muscular System Main function of a muscle: Contraction (shortening) Because muscles can contract: The main functions of the muscular system are: Movement Maintains Posture Stabilizes Joints Generates Heat Controls Openings (sphincters) Expressions Protection (reflexes)

Three basic muscle types are found in the body Skeletal muscle Cardiac muscle Smooth muscle can you distinguish which is which?

Characteristics of Muscles Skeletal and smooth muscle cells are elongated ***(a muscle cell is also referred to as a muscle fiber) Some skeletal muscle cells can be up to a foot long in length All muscles share some terminology If you see myo- mys- or sarc- you think MUSCLE! Prefixes myo and mys refer to “muscle” Prefix sarco refers to “flesh”

Comparison of Skeletal, Cardiac, and Smooth Muscles Table 6.1 (1 of 2)

Comparison of Skeletal, Cardiac, and Smooth Muscles Table 6.1 (2 of 2)

Terminology Review Endo- Inside, Within (endoskeleton) Peri- Around, surround (perimeter) Epi- On, over, above (epidermis)

Our Focus: SKELETAL MUSCLE (Striated)

Skeletal Muscle Characteristics Attached to the skeleton Attached by tendons to bones (or aponeuroses) Cells are multinucleate (many nuclei) Striated (have visible banding) Strong force Tire easily (muscle fatigue) Voluntary—you control them (exception = reflexes)

Connective Tissue Wrappings of Skeletal Muscle Cells are surrounded and bundled by connective tissue Endomysium—encloses a single muscle fiber Perimysium—wraps around a group of muscle fibers forming a fascicle (bundle of muscle fibers) Epimysium—covers the entire skeletal muscle (many fascicles)

Connective Tissue Wrappings of Skeletal Muscle Figure 6.1

Let’s build a model of a muscle.