190 likes | 413 Views
The Musculo skeletal System Support, Protection, Movement and Locomotion. Characteristics of muscle tissue. Excitability – receive and respond to stimuli Contractility – shorten and thicken Extensibility – stretch and extend
E N D
The Musculoskeletal SystemSupport, Protection, Movement and Locomotion
Characteristics of muscle tissue • Excitability – receive and respond to stimuli • Contractility – shorten and thicken • Extensibility – stretch and extend • Elasticity – return to original shape after contraction or extension
Functions • Motion • Maintenance of posture • Heat production • Protection of internal organs
Origin of muscle tissue • Forms from the mesoderm germ layer • Triploblasts simplest: flatworms • Segmentation annelids, arthropods, vertebrates
Types of muscle tissue • Skeletal • Attached to bones • Striated and voluntary • Cardiac • Heart wall • Highly branched • Striated and involuntary • Smooth • Walls of hollow internal structures • Nonstriated and involuntary • Striated • Voluntary movements • Longitudinal or circular in shape • Smooth • Involuntary movements Vertebrate muscles Invertebrate muscles
Muscle action • Motion produced by action of muscles on bones levers • Tendons attach muscles to bones (e.g. Achilles tendon) • 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion) • Fascia sheets that cover muscles • Muscles work in antagonistic or opposing pairs
Muscle movement • Adduction • Abduction • Flexion • Extension • Rotation • Sphincters • Levators • Depressors • Supination • Pronation
Anatomy of skeletal muscles epimysium tendon perimysium Muscle Fascicle Surrounded byperimysium endomysium Skeletal muscle Skeletal muscle fiber (cell) Surrounded by epimysium Surrounded by endomysium
Overview of the Sliding Filament Theory The muscle fiber is stimulated. Ca2+ ions are released. Thin filaments move to middle of sarcomere. Muscle fiber contracts. Muscle tension increases.
Muscle twitch • Cycle of contraction and relaxation generated from one stimulus • All or none response of muscle fibers • Force Summation • Increasing # and size of fibers contracting • Increasing frequency at which action potentials are sent to muscle fibers
Slow and Fast Twitch Fibers • Slow Twitch • More ATP from aerobic respiration • Continuous extended contractions over time • More myoglobin • Fast Twitch • Anaerobic metabolism (creatine phosphate and lactic acid fermentation) • Short bursts of speed • Fatigue quickly
Cramps • Painful sensations caused by contraction/ overshortening of muscles • Causes • Hyperflexion • Inadequate oxygenation • Changes in temperature • Dehydration • Low amount of electrolytes in blood • Treatment • Correct breathing • Increasing intake of water and electrolytes