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Applied Exercise Physiology. Section 5: Body Systems Topic 1: Muscular System. Prepared by Mr. Cerny Niagara Wheatfield Senior High School. Cardiac Heart Smooth Organ lining Skeletal Movement 40% of total body mass. Types of Muscle. Types of Muscle (con’t). Cardiac. Skeletal.
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Applied Exercise Physiology Section 5: Body Systems Topic 1: Muscular System Prepared by Mr. Cerny Niagara Wheatfield Senior High School
Cardiac Heart Smooth Organ lining Skeletal Movement 40% of total body mass Types of Muscle
Types of Muscle (con’t) Cardiac Skeletal Smooth
Skeletal Muscle • How many different muscles can there be? • ~660
Cable wire c.s. Skeletal Muscle Structure • Cylindrical fibers bunched together
Macrostructure • It is the number of muscle fibers packed into a given muscle cross-sectional area that determine overall force-generating capacity Skeletal muscle c.s. 40x
Microstructure Sarcomere: • basic functional unit of muscle • Striated (light & dark bands) • Contains ACTIN & MYOSIN filaments that are responsible for contraction
Where did the Ca++ come from? • Ca++ is stored and released from the sarcoplasmic reticulum (SR) • SR is a network of tubules within the muscle fiber
Excitation-Contraction Coupling • Action potential travels along neuron by the temporary changing of charges • Nerve impulse causes the release of acetylcholine (ACh). • ACh travels across neuromuscular junction, binding to muscle cell membrane. • ACh binding initiates an electrical impulse which travels across membrane and into T tubules. • Impulse stimulates release of Ca+2 from SR. • Ca+2 binds with t-t complex of the actin filaments, shifting it's position, exposing myosin binding sites. • Myosin binds to actin; Ca+2 presence also causes enzymatic actions of myosin to breakdown ATP into ADP + P + energy. • Energy of ATP degradation causes shape change of myosin head, pulling actin molecule toward center of sacromere. • After sliding, a new ATP binds to myosin, breaking the myosin-actin bond, releasing the myosin head. • If Ca+2 is still present, the process repeats itself until sacromere has shortened completely. • If a nerve impulse ceases, the Ca+2 is reabsorbed by the SR and the muscle relaxes.
Muscle Fatigue 1 What causes it? • 1) Reduction in ATP • Under high stress, ATP utilization reduced faster than ATP production • 2) Peripheral metabolic bi-products • Lactic acid • H (and other free radicals)
Muscle Fatigue • 3) Dehydration • Increases temp = decreases contractile properties • 4) Decrease nerve signals/action potentials • 5) Reduction of Ca • “leakage” 1 • From decrease nerve connection
Muscle Strength “Bigger” muscles: • Usually NOT increase in muscle cells (hyperplasia) • Usually an increase in existing tissue size (hypertrophy) Factors contributing: • Genetics • Exercise • Nutrition • Endocrine • Environmental • Nervous
The Muscular System 11.0 Describe Animal Health Needs 11.3 Describe the musculoskeletal system
Function of the muscular system • Provides movement in conjunction with the skeletal system • Important in life support • Used by humans and other animals for food
Classifications of Muscles • Voluntary: Movement of the muscle is under the control of the animal • Involuntary: Movement of the muscle is not controlled by the animal
Types of Muscles • Smooth Muscles: Involuntary muscles, found in the walls of internal organs and the blood vessels.
Smooth Muscles • Are not under voluntary control • Are spindle shaped and are not striated. • Interlace to form Sheets of smooth muscle tissue. • Are found in many internal organs: Stomach, Intestines, Blood Vessel walls
Types of Muscles • Cardiac Muscles: Muscles that form a network to make up the heart. Not under active brain controll
Cardiac Muscles • Only found in the Heart • Are Striated • Are NOT under Voluntary Control • Contract Without Direct stimulation by the Nervous System
Types of Muscles • Skeletal Muscles: Have a striped appearance, include voluntary and involuntary, attached to and moves your bones. This is a majority of the muscle tissue in your body.
Skeletal Muscles • Are made of Elongated Cells called MUSCLE FIBERS • Are grouped into dense bundles called FASCICLES • Are LARGE and have MORE than ONE NUCLEUS • Most are Voluntary