Muscle Tissue Types Quiz

Muscle Tissue Types

• Muscle tissue is specialized tissue with several functions:
  • Excitability: Receives and responds to stimulation from the nervous system via electrical signals (action potentials).
  • Contractility: Shortens and thickens, generating force and movement.
  • Extensibility: Lengthens.
  • Elasticity: Returns to its resting state.
• Functions of muscle tissues:
  • Maintain posture
  • Support soft tissues
  • Guard entrances/exits
  • Maintain body temperature (thermogenesis)
  • Circulate blood
  • Move substances
  • Facilitate breathing

Skeletal Muscle

• Characteristics:
  • Long, cylindrical, striated fibers
  • Multinucleated
  • Voluntary
  • Location: Attached to bones
  • Function: Movement
  • Striations: Regular arrangement of actin and myosin filaments
  • Myosin: Converts chemical energy (ATP) to mechanical energy for movement
  • Actin: Works with myosin for contraction
  • Connective Tissues: Epimysium (outermost), Perimysium (bundles), Endomysium (individual fibers), support, repair, regeneration
  • Neuromuscular Spindles: Stretch receptors for proprioception, reflex action, motion control
  • Located in nearly all skeletal muscles and comprise of a connective tissue capsule, containing intrafusal fibers and nerve endings
• Neuromuscular Spindles: Monitor muscle length changes and regulate muscle activity through complex reflexes

Smooth Muscle

• Characteristics:
  • Spindle-shaped, non-striated fibers
  • Uni-nucleated
  • Involuntary
  • Location: Hollow organs, blood vessels
  • Function: Slow, involuntary movements, e.g., peristalsis (digestion), vasoconstriction (blood vessel pressure), vasodilation (blood vessel relaxation)
  • Cytoplasm (sarcoplasm): Specialized filling of the smooth muscle cells
  • Cell Membrane (sarcolemma): Thin cell membrane surrounding the cell.

Cardiac Muscle

• Characteristics:
  • Striated, involuntary
  • Location: Heart walls and large vessels.
  • Function: Pumps blood, rhythmical beating (lub-dub).
  • Intercalated disks: Contain gap junctions (connections) and desmosomes (strengthening points) to allow for rapid communication and coordination.
  • Striated: Exhibits cross-striations due to actin and myosin arrangement
  • Electron microscopic view: A bands (contraction), I band (overall contraction process), Z lines (boundaries of sarcomere providing structural support) and sarcomere (units).
  • Typically only one or two centrally located nuclei, and branching.
  • Extra heartbeats (heart murmurs) can occur due to various abnormalities in the contraction and function.