The Muscular System

Muscle Control Type of muscle Nervous control Type of control Example Skeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis

Types of Responses Twitch- –A single brief contraction –Not a normal muscle function Tetanus –One contraction immediately followed by another –Muscle never completely returns to a relaxed state –Effects are compounded

Where Does the Energy Come From? Energy is stored in the muscles in the form of ATP ATP comes from the breakdown of glucose during Cellular Respiration This all happens in the Mitochondria of the cell When a muscle is fatigued (tired) it is unable to contract because of lack of Oxygen

Muscle Contraction 1.The nerve impulse from motor neuron reaches synapse. 2.The impulse triggers the release of acetylcholine in the synapse. 3.Acetylcholine binds to receptors on surface of muscle cell, triggers an impulse. 4.Calcium ions in sarcoplasmic reticulum move toward bind to troponin. 5.Troponin moves out, allowing actin and myosin to react. 6.The thin actin filaments slides inside the myosin filaments, shortening. This is repeated for each sarcomere, along the muscle fiber. This causes a shortening of the entire muscle.

Muscle Relaxation 1.An enzyme present in the synaptic cleft, acetylcholinesterase, destroys Ach shortly after it is bound to the receptors. The membrane, thus, no longer, responds to impulse. 2.Ca ++ goes off troponin and is transported by into its storage vesicles (using ATP). Actin and myosin are no longer linked. 3.The sarcomere slides back into resting position. The muscle relaxes.

Muscle Contractions Isotonic- muscles shorten/lengthen and movement occurs (most normal exercise) Isometric- muscle is activated, but it is held at a constant length

Injuries to the Muscles Just like our skeletal system, sometimes we may injure our muscles.

Types of Injuries Contusions (muscle bruises) –One of most common experienced by athletes –Often caused by direct trauma/repeated blow Muscle Strains –Occurs when muscle is overstretched or pulled –Can be caused by sudden/forceful contraction of muscle (lifting heavy weight) Tendonitis (inflammation of the tendon) –Occurs when tendon is irritated and inflamed –Can be caused by sudden pull on tendon and overuse/repetitive movements

Muscle Strains Tears are often called pulled or strained muscles. The degree of the injury will determine treatment and recovery time.

Categories of Muscle Strains Grade I Strain: This is a mild strain and only some muscle fibers have been damaged. Healing occurs within two to three weeks. Grade II Strain: This is a moderate strain with more extensive damage to muscle fibers, but the muscle is not completely ruptured. Healing occurs within three to six weeks. Grade III Strain: This is a severe injury with a complete rupture of a muscle. This typically requires a surgical repair of the muscle; the healing period can be up to three months.

Body Building Many people work very hard to build their muscles. They use various exercises to build strength and muscle mass. This is a common practice with many men and women today, and many compete in contests.

How much is too much?

Flexion Types of Musculo-Skeletal Movement

Extension

Hyperextension

Abduction, Adduction & Circumduction

Rotation

More Types of Movement…… Inversion- turn sole of foot medially Eversion- turn sole of foot laterally Pronation- palm facing down Supination- palm facing up Opposition- thumb touches tips of fingers on the same hand