Muscular System

Types of muscle tissue Muscle tissue has the function of movement There are 3 types of tissue Skeletal Attached to bones - moves bones Voluntary control Cells are striated (striped) and long (muscle fibers) Smooth muscle Line the tubes in your body (digestive tract, arteries, etc) - pushes stuff through tubes Involuntary Cells are spindle shaped, not striated Cardiac muscle Found in heart - makes heart beat Cells are striated but short

Skeletal muscles, muscle tissue, muscle cells Muscles are made of BUNDLES of muscle fibers Muscle fibers ARE muscle cells The muscle cells are filled with protein cables called filaments

How muscles and bones interact Muscles are attached to bone by tendons A muscle must cross one joint to cause movement A muscle can only pull in one direction Muscles come in opposing pairs Bicep - flex arm Tricep - extend arm Both of these muscles cross the elbow joint

Control of skeletal muscle contraction Voluntary Neurons near the muscle receive a message from the brain to contract The electrical impulse from the neuron tells the muscle cells to contract A muscle can do more work when more of its cells are told to contract

Skeletal muscle contraction Muscle fibers are filled with protein cables called filaments Myosin = thick filaments Actin = thin filaments When a muscle contracts The myosin grabs onto the actin The myosin pulls the actin toward the center The muscle shortens (contracts) The muscle relaxes when the myosin “lets go” The energy for contraction Is supplied by ATP ATP is made from glucose and oxygen When you run low on glucose and oxygen, the muscle becomes FATIGUED

Muscle contraction

Muscles and exercise Muscle tone Muscles are in a state of partial contraction Exercise Aerobic Heart, lungs more efficient Weight training When you lift weights you break the actin and myosin filaments Your body then builds more You gain strength and size Bones get stronger Proper exercise enhances CV health, strength, and flexibility