Muscular system


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Muscular system

  1. 1. MUSCULAR SYSTEM <ul><li>This system is responsible for the movement and locomotion of a body. This system is composed of skeletal muscles, cardiac muscles, and smooth muscles. </li></ul>
  2. 2. Smooth Muscles <ul><li>Smooth Muscle lacks the visible cross-striations, but, unlike skeletal and cardiac muscle; it is found mostly in the walls of hollow viscera such as intestines. </li></ul>
  3. 3. <ul><li>Smooth muscle’s continuous contractions provide the motive power for digestion, secretion and excretion. Like cardiac muscle, smooth muscle is normally under the dual control of hormones and the autonomic nervous system, but it also has intrinsic contractility and it is not under voluntary control. </li></ul>
  4. 4. Cardiac Muscles <ul><li>The hearts of vertebrates are composed of this kind of muscle. Compared to the skeletal muscle, it has a smaller, interconnected cells, each with a single nucleus. </li></ul>
  5. 5. <ul><li>Cardiac muscles also has cross-striations, but, unlike somatic muscle fibers, its fibers branch and interdigitate so that the mass of muscle tends to function as one unit or syncytium. Cardiac muscle will continue to contract rhythmically when the nerve supply is cut. </li></ul>
  6. 6. Skeletal Muscles <ul><li>Skeletal muscles are straited muscle because of their striped appearance under the microscope. This muscle produce movement of the skeleton when they contract. </li></ul>
  7. 7. <ul><li>Skeletal Muscles comprise the great bulk of the somatic (body) musculature (about 40% of the total body weight). Skeletal muscle fibers do not normally contract in the absence of nervous stimulation and they are mostly under voluntary control. The muscles of the arms and legs are examples. Skeletal muscle is also known as striped, striated, somatic or voluntary muscle. </li></ul>
  8. 8. Muscle fiber and its compositions <ul><li>The functional element of skeletal muscle is the muscle fiber, which may vary from 1 to 50 mm in length and 10 to 100 μ m in width. Each muscle fiber has many fine threads or myofibrils running throughout its length. </li></ul>
  9. 9. Myofibrils and Myofilaments <ul><li>Each muscle fiber encloses a bundle </li></ul><ul><li>of 4 to 20 elongated structures called Myofibrils and each myofibrils is </li></ul><ul><li>composed of thick </li></ul><ul><li>and thin </li></ul><ul><li>myofilaments. </li></ul>
  10. 10. The Myosin and Actin <ul><li>Myofibril contains two different types of still inner myofilaments. The thicker myofilaments consist of the protein myosin and each is surrounded by a hexagonal arrangement of thinner actin myofilaments. </li></ul>
  11. 11. Sarcomere <ul><li>Thick and thin myofilaments are stacked together to produce the dark bands, called A-bands; the thin filaments alone are found in the light bands, or I-bands. Each I-band in a myofibril is divided in half by a disc of protein, called a Z-line because of its appearance in the electron micrographs. The thin filaments are anchored to these discs of proteins that form the Z-line. This repeating structure, called a Sarcomere, is the smallest subunit of muscle contraction. </li></ul>
  12. 12. The Sarcomere