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Prefixes and Suffixes • • • • • • • • blast = budding or germ clast = break myo- = muscle sarco – flesh - algia or alg(i)o = pain arthr(o) = pertaining to the joints or limbs - ase = enzyme fibr(o) = fiber What make up the bulk of the body and account for about 30 – 40% of its weight? MUSCULAR SYSTEM • a muscle is a tissue composed of fibers capable of contracting to effect bodily movement Cardiac Muscle • makes up the walls of the heart • cells are striated; one central nucleus • involuntary – cannot be controlled • contractions propel blood throughout the body Smooth Muscle • found in the walls of hollow organs – ex: stomach, intestines, blood vessels • no striations; one central nucleus • involuntary • moves substances along internal passageways Skeletal Muscle • Provides movement for body parts • Made up of muscle tissue, nervous tissue, blood and connective tissue – attached to bones, cartilage, tendons or skin • have striations, dark bands or stripes – results from the presence of two types of protein filaments • voluntary control • cells have multiple nuclei MUSCLE STRUCTURE • muscle cells are called muscle fibers • contract in response to stimuli • each muscle fiber (cell) is made up of many myofibrils – myofibrils • a rod-like structure that contracts when stimulated • made up of two types of filament: actin (thin) and myosin (thick). – Filaments are made up of proteins • consist of sections called sarcomeres Sarcomeres • functional unit of skeletal muscle • Extends from one Z line to the next Z line • Z line – location where actin filaments are anchored at their endpoints http://videos.howstuffworks.com/hsw/6100-the-cellmuscle-cells-video.htm Contracting a Muscle • Myosin and actin interact to shorten the length of a sarcomere • myosin attaches to the actin • The myosin head bends inward, pulling the actin with them • This action shortens the length of the sarcromere http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter42/animations. html# http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter10/animation__ myofilament_contraction.html During contraction, the thin filaments slide past the thick During contraction, the thin filaments slide past the thick filaments, shortening the sarcomere –all sarcomere shorten simultaneously, causing the entire muscle fiber and the muscle to contract Motor Units • The trigger for a muscle contraction is an electrical impulse. –signals sent from the central nervous system. (brain and spinal cord) • A motor neuron (nerve cell) and all the muscle fibers that it stimulates are known as the motor unit. Neuromuscular Junction • Connection between the motor neuron and muscle fiber O2 Supply and Cellular Respiration • Blood carries O2 from the lungs to body cells • Myoglobin stores O2 in muscle tissue, reducing need of blood supply • O2 required for cellular respiration – C6H12O6 + O2 CO2+ H2O + ATP O2 Debt • During strenuous activity muscle fibers have an increase need for energy • Not enough O2 leads to anaerobic (without O2) respiration – Results in build a up of lactic acid in the muscles - Lactic acid can be converted back to glucose by the liver • active muscles use a lot of energy and require a continuous supply of oxygen and nutrients (how is this supplied?) • Muscle fatigue – Inability of a muscle to contract – Results as a depletion of ATP – During rigorous activity the blood cannot transport enough Oxygen to function properly • Cellular Respiration – Lactic acid is produced as a waste product • presence of waste results in soarness • MUSCLES THAT ARE EXERCISED REGULARLY form more cappilaries and mitochondria • When the triceps muscle (extensor) contracts, it opens, or extends, the elbow joint. Hw: • What is the relationship between cellular respiration and heat production? • Why are steroids considered unhealty? HOW MUSCLES AND BONES INTERACT • muscles generate force and produce movement by contracting or pulling on body parts – individual muscles can only pull; they cannot push • skeleton muscles are attached to bone, stretch across a joint, and are attached to the end of another bone – tendons connect muscle to bone • one bones is usually more stationary than the other • The point where the muscle attaches to the stationary bone is called the origin • The point where the muscle attaches to the more moveable bone is the insertion – A muscle’s insertion bone moves toward its origin bone • Most skeletal muscles work in pairs • When one muscle or set of muscles contracts, the other relaxes. • Flexor, a muscle that bends a joint. Extensor, a muscle that straightens a joint • When the biceps muscle (flexor) contracts, it bends or flexes the elbow joint • A controlled movement requires contraction by both muscles • A muscle pulls when it contracts, but exerts no force when it relaxes and CANNOT PUSH. When one muscle Pulls a bone in one direction, another muscle is needed to PULL the bone in the other direction.