2OutlineTypes and Functions of MusclesSmoothCardiacSkeletalMuscle InnervationWhole Muscle ContractionOxygen DeficitAthletics and Muscle ContractionSlow and Fast Twitch FibersMuscle Disorders
3Types and Functions of Muscles Smooth muscle is located in the walls of hollow internal organs and contracts involuntarily.Cardiac muscle forms the heart wall and contracts involuntarily.Skeletal muscle runs the entire length of the muscle and contracts voluntarily.Cells are muscle fibers
5Functions of Skeletal Muscles Body support.Bone movement.Maintenance of body temperature.Assist movement in cardiovascular and lymphatic vessels.Protect internal organs.Stabilize joints.
6Skeletal Muscles of the Body A whole muscle contains bundles of skeletal muscle fibers, fascicles.Muscles are covered with fascia that becomes tendons.Muscles originate on the stationary bone, and insert on the bone that moves.
8Names and Actions of Skeletal Muscles Skeletal muscles are named based on characteristics.Size. Gluteus maximusShape. DeltoidDirection of muscle fibers. Rectus abdominusNumber of attachments. Biceps brachiiAction. Extensor digitorum
10Skeletal Muscle Fiber Contraction Overview of Muscular Contraction.Nerve impulses originate in the brain, travel down motor neurons, and stimulate muscle fibers at neuromuscular junctions.When muscle fibers are stimulated to contract, myofilaments slide past one another, causing sarcomeres to shorten.
13light and dark bands (striations) sarcomeres thin filaments – actinthick filaments - myosinZ line, A band, I band, H zoneSliding Filament Theory – actin and myosinfilaments moving. Myosin does work. ATP
21Whole Muscle Contraction Muscle Twitch - Single muscle contraction.Divided into three stages.Stimulation.Contraction.Relaxation.If a muscle is given a rapid series of threshold stimuli, muscle contraction summates in a sustained contraction, tetanus.
23Whole Muscle Contraction A motor neuron, together with all of the muscle fibers that it innervates, is a motor unit.As the intensity of nervous stimulation increases, more motor units are activated.(recruitment)
24Energy for Muscle Contraction ATP produced previous to strenuous exercise lasts a few seconds, and then muscles acquire new ATP in three ways.Phosphate breakdown. (anaerobic)Fermentation. (anaerobic)Cellular respiration. (aerobic)
28Oxygen DeficitWhen a muscle uses the anaerobic means of supplying energy, it incurs an oxygen deficit.Repaying an oxygen deficit requires replenishing creatine phosphate supplies and disposing of lactic acid.
29Athletics and Muscle Contraction Muscles that are not used, or are used in only weak contractions can atrophy.Can cause muscle fibers to progressively shorten, leaving body parts contracted in contorted positions.forceful exercise can cause muscle size to increase or hypertrophy.
30Athletics and Muscle Contraction Slow-twitch fibers produce most of their energy aerobically and tire only when their fuel supply is gone.Fast-twitch fibers tend to be anaerobic and seem to be designed for strength as their motor units contain many fibers.Can develop greater, and more rapid, maximum tension than slow-twitch fibers.
32HomeostasisCardiac muscle contraction accounts for the heartbeat, delivering blood to the tissues.Smooth muscle contraction accounts for peristalsis and urination.Skeletal muscle contraction returns blood to the heart and moves bones, allowing for body movement.