The Muscular System: Function & Muscle Types

The Muscular System Functions: Produce movement Maintain posture Stabilize joints Generate heat

Muscle Types Three basic muscle types are found in the body Skeletal muscle Smooth muscle Cardiac muscle

Skeletal Muscle Characteristics Body Location: Most are attached by tendons to bones or, for facial muscles, to skin Cell Shape and Appearance: Single, very long cylindrical, multinucleate cells Striated – have visible banding

Skeletal Muscle Characteristics Regulation of Contraction: Voluntary – subject to conscious control Speed of Contraction: slow to fast Rhythmic contraction: no

Anatomy of a Skeletal Muscle Each muscle fiber is enclosed in a delicate connective tissue sheath called an endomysium. A bundle of muscle fibers are then wrapped in a coarser fibrous membrane called a perimysium. Figure 6.1

Anatomy of a Skeletal Muscle The bundle of fibers enclosed in the perimysium then forms a fascicle. Many fascicles are then bound together by a even tougher connective tissue called an epimysium. Figure 6.1

Anatomy of a Skeletal Muscle The epimysia blend together to form strong, cordlike tendons which attach muscles to bone, cartilages, or connective tissue coverings. Figure 6.1

Anatomy of a Skeletal Muscle Tendon Functions: Provide durability Conserve space Cross rough bony projections due to their tough collagen fibers

Smooth Muscle Characteristics Body Location: Mostly in walls of hollow visceral organs (other then the heart) Cell Shape and appearance: Has no striations Figure 6.2a

Smooth Muscle Characteristics Regulation of Contraction: Involuntary – no conscious control Speed of Contraction: Very slow Rhythmic Contraction: Yes, in some Figure 6.2a

Cardiac Muscle Characteristics Body Location: found only in the heart Cell Shape and Appearance: Has striations Joined to another muscle cell at an intercalated disc Figure 6.2b

Cardiac Muscle Characteristics Regulation of contraction: Involuntary Speed of contraction: slow Rhythmic contraction: yes Figure 6.2b