![]() → Involuntary muscles: Smooth muscle activities are not under the voluntary control of the nervous system and are therefore known as in-voluntary muscles. Hence, they are called smooth muscles (non-striated muscles). → Smooth muscles (nonstriated muscle): Visceral muscles do not exhibit any striation and are smooth in appearance. → Voluntary muscles: As striated muscle activities are under the voluntary control of the nervous system, they are known as voluntary muscles too. → Striated muscles: Skeletal muscles have a striped appearance under the microscope and hence are called striated muscles. → Locomotion: Such voluntary movements i.e., limbs, jaws, eyelids, tongue, etc. → Synovial joints allow considerable movements and therefore, play a significant role in locomotion. → Three types of joints are formed between bones or between bone and cartilage: Limb bones and girdles form the appendicular skeleton. → Skull, vertebral column, ribs, and sternum constitute the axial skeleton. The skeletal system is divisible into axial and appendicular. → Bones and cartilages constitute our skeletal system. Muscles are classified as Red and White fibers based primarily on the amount of red-colored myoglobin pigment in them. → Repeated stimulation of muscle leads to fatigue. Cross bridges are broken and the muscles relax. → Ca are then returned to the sarcoplasmic reticulum which inactivates the actin. These cross bridges pull the actin filaments causing them to slide over the myosin filaments and thereby causing contraction. → Ca + + activates actin which binds to the myosin head to form a cross bridge. This causes the release of Ca + + from the sarcoplasmic reticulum. → A motor neuron carries the signal to the muscle fiber which generates action potential in it. → Myosin head contains ATP phase and has ATP binding sites and active sites for actin. → Actin and myosin are polymerized proteins with contractility, the active sites for myosin on resting actin filament are masked by a protein- troponin. → Each sarcomere has a central A-bond made of thick myosin filaments, and two half I-bands made of thin actin filaments on either side of it marked by Z lines. contain many serially arranged units called sarcomere which is the functional unit. Each muscle fiber has many parallelly arranged myofibrils. → A muscle fiber is the anatomical unit of muscle. ![]() → Muscles possess excitability, contractility, extensibility, and elasticity. They are striated, branched, and involuntary. → Cardiac muscles are the muscles of the heart. → Visceral muscles, present in the inner walls of visceral organs are nonstriated and involuntary. They appear united and are voluntary in nature. → Skeletal muscles are attached to skeletal elements. → Three types of muscles are present in our body. → Locomotion and many other movements require coordinated muscular activities. → The cell of the human body exhibit amoeboid, ciliary, and muscular movements. → Animals move generally in search of food, shelter, mate, breeding ground, a better climate or to protect themselves.
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