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Understanding Muscle Tissue Types and Functions

Apr 9, 2025

Overview of Muscular Tissue

Muscle tissue accounts for nearly half of the body's mass and transforms chemical energy (ATP) into mechanical energy to exert force through contraction.

Terminology

  • Prefixes: "myo," "mys," and "sarco" all refer to muscle.

Types of Muscle Tissue

  1. Skeletal Muscle

    • Characteristics:
      • Contains skeletal muscle tissue packaged into units known as fascicles.
      • Attached to bones and skin.
      • Considered an organ due to the presence of connective tissues, blood vessels, and nerves.
      • Contains long fibers that can be several feet in length and have multiple nuclei.
      • Striated (striped) and voluntarily controlled.
      • Contracts rapidly, tires easily, and is powerful.
    • Keywords: Striated, Voluntary

  2. Cardiac Muscle

    • Characteristics:
      • Found only in the heart, making up the bulk of the heart walls.
      • Striated but involuntary.
      • Contracts at a steady rate due to the heart's pacemaker; the nervous system can increase its rate.
      • Shorter cells, not called fibers, have 1-2 nuclei and are interconnected by intercalated discs (gap junctions and desmosomes).
      • Highly branched, giving a disorganized appearance.
    • Keywords: Cardiac, Striated, Involuntary

  3. Smooth Muscle

    • Characteristics:
      • Located in walls of hollow organs (e.g., gastrointestinal tract, respiratory tract, blood vessels).
      • Not striated and involuntary.
      • Capable of contracting autonomously without nervous system input.
      • Functions in propulsion of materials and regulation of flow and pressure.
    • Keywords: Smooth, Involuntary

Key Characteristics of Muscle Tissue

  • Excitability: Ability to receive and respond to stimuli (electrical or chemical).
  • Contractility: Ability to shorten forcibly when stimulated.
  • Extensibility: Ability to be stretched.
  • Elasticity: Ability to recoil to resting length after stretching.

Functions of Muscle Tissue

  • Movement Production:
    • Skeletal muscle: walking.
    • Smooth muscle: digestion.
    • Cardiac muscle: pumping blood.
  • Posture and Body Position: Maintained by skeletal muscle.
  • Joint Stabilization: Another function of skeletal muscle.
  • Heat Generation: Skeletal muscle contracts during shivering to produce heat.

Additional Functions

  • Protection
  • Valve formation
  • Pupil size control
  • Goosebumps formation

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