Muscles Physiology PDF

Physiology of muscles: 10. Types of muscles. Skeletal muscle: Voluntary, under conscious control, attaches to bones and enables movement Cardiac muscle: Involuntary regulated by autonomic nervous system and pacemaker cells. Smooth muscle: Involuntary, found in walls of hollow organs, controls conten...

Physiology of muscles: 10. Types of muscles. Skeletal muscle: Voluntary, under conscious control, attaches to bones and enables movement Cardiac muscle: Involuntary regulated by autonomic nervous system and pacemaker cells. Smooth muscle: Involuntary, found in walls of hollow organs, controls content movement through lumen. 11. Functions and properties of muscles Functions: - Movement: Skeletal muscles move the body by contracting and pulling on tendons. - Posture: Maintain body posture against gravity - Support: Protect internal organs (abdominal muscles) - Control of openings: Sphincters regulate the openings of body orifices - Peristalsis: Smooth muscles propel content in tubular organs - Blood flow: Cardiac muscle pumps blood, smooth muscle in vessels regulates flow - Temperature regulation: Converts metabolic energy to heat Properties: - Excitability: Respond to stimuli - Contractility: Shorten and produce force - Extensibility: Stretch without damage - Elasticity: Return to original shape after stretching - Conductivity: Conduct electrical impulses 12. Structure of a skeletal muscle. Composed of muscle fibers (cells) bundled into fascicles - T-tubules: Conduct impulses into fibers - Sarcoplasmic reticulum (SR): Stores and releases calcium for contraction - Myofibrils: Composed of actin (thin) and myosin (thick) filaments 13. Sarcomere The basic contractile unit of a started muscle cell. - Z lines, contains I band, A bands, H zones and M lines - Sliding filaments theory: Actin and myosin filaments slide past each other during contraction 14. Analysis of muscle contraction (Neuromuscular Junction, Sliding Filament Theory, Contraction of Motor Units, Contraction of Whole Muscle – lab work). 15. Types of muscle contraction Isotonic: Muscle changes length under constant tension, for example lifting weights. Isometric: Muscle tension increases without changing length 16. Muscle tone and motor units Muscle tone: Baseline muscle tension maintaining posture and readiness Motor unit: A single motor neuron and the muscle fibers it contains, size varies depending on precision needed 17. Tetanus A sustained muscle contraction resulting from rapid and repeated stimulation 18. Muscular work Involves contraction and relaxation cycles powered by ATP. Prolonged work leads to fatigue and oxygen debt 19. Skeletal muscle fatigue Caused by depletion of energy reserves (ATP, glycogen), accumulation of lactic acid, or impaired calcium release. 20. Types of muscle fibers Type I: Slow- twitch, red, fatigue- resistant, efficient in prolonged, low- intensity activity Type II: Fast- twitch, white: - Ila: Fast oxidative, moderately resistant to fatigue - Ilb/Ilx: Fast glycolytic, powerful but fatigue quickly 21. Training Regular exercise improves muscle size, strength, endurance, and resistance to fatigue. It also enhances overall metabolism, circulation, and lung efficiency 22. The kinesthetic sense-proprioreceptors. Muscle spindles: Detect muscle length and changes in length Golgi tendon organs: Sense tension and protect muscles from excessive force Joint receptors: Provide information about joint angle and motion