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Lab exam 2 - exercise 12

컨트롤 버튼이 '내비게이션' 모드로 변경되었습니다.
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이 집합의 용어 (20)

  • What is skeletal muscle and its primary function?
    Skeletal muscle attaches to the skeleton or connective tissue and is under voluntary control. Its primary functions are shape and movement.
  • What are the main components of a skeletal muscle cell?
    Skeletal muscle cells are long cylindrical muscle fibers with a membrane called sarcolemma and cytoplasm called sarcoplasm. They are multinucleated with nuclei arranged peripherally.
  • What are myofibrils and their role in skeletal muscle?
    Myofibrils are rod-shaped bundles of myofilaments inside muscle fibers, responsible for contraction. They create the muscle's striped appearance with alternating light (I) and dark (A) bands.
  • What proteins compose the myofilaments in skeletal muscle?
    Myofilaments are made of contractile proteins: thick filaments contain myosin, and thin filaments contain actin.
  • Describe the banding pattern of myofibrils.
    Myofibrils have alternating light I bands and dark A bands. The A band contains a lighter H zone bisected by the M line, and the I band has a midline Z disc.
  • What is a sarcomere?
    A sarcomere is the smallest contractile unit of a muscle fiber, spanning from one Z disc to the next, containing an A band with half an I band on each side.
  • What is the function of the transverse tubule (T tubule)?
    The T tubule is an indentation of the sarcolemma at the A-I band junction that conducts impulses deep into the muscle fiber to trigger Ca2+ release.
  • What structures form a triad in skeletal muscle?
    A triad consists of two terminal cisterns of the sarcoplasmic reticulum flanking one T tubule.
  • What connective tissue layers surround skeletal muscle fibers and muscles?
    Endomysium surrounds each muscle fiber, perimysium surrounds fascicles (bundles of fibers), and epimysium surrounds the entire muscle.
  • What is a fascicle in skeletal muscle?
    A fascicle is a bundle of muscle fibers surrounded by perimysium.
  • How do muscles attach to bones?
    Muscles attach directly when epimysium fuses to bone periosteum or cartilage perichondrium, or indirectly via tendons or aponeuroses.
  • Define origin and insertion in muscle attachment.
    Origin is the muscle attachment to the immovable or less movable bone; insertion is the attachment to the movable bone.
  • What is the neuromuscular junction?
    The neuromuscular junction is the synapse between a motor neuron axon terminal and a muscle fiber where nerve impulses trigger muscle contraction.
  • What is the synaptic cleft?
    The synaptic cleft is the small fluid-filled gap between the motor neuron axon terminal and the muscle fiber membrane.
  • What neurotransmitter is released at the neuromuscular junction?
    Acetylcholine (ACh) is released from the axon terminal, diffuses across the synaptic cleft, and binds to receptors on the sarcolemma.
  • How does acetylcholine trigger muscle contraction?
    ACh binding opens ion channels on the sarcolemma, causing an action potential that leads to muscle fiber contraction.
  • What is a motor unit?
    A motor unit consists of one motor neuron and all the muscle fibers it stimulates.
  • Why are skeletal muscle cells multinucleated?
    They are multinucleated because they form from the fusion of many myoblasts, allowing for peripheral nuclei placement due to myofibril arrangement.
  • What is the role of the sarcoplasmic reticulum in muscle cells?
    The sarcoplasmic reticulum stores and releases Ca2+ ions essential for muscle contraction.
  • What is the function of tendons in muscle anatomy?
    Tendons connect muscle to bone, providing durability and conserving space by spanning bony projections.