Ch 10

Overview of Muscle Tissue

  • Three types of muscle tissue: skeletal, cardiac, smooth.
  • Basic function: generate muscle tension.
  • Additional functions: movement, posture, joint stability, heat generation, regulation of material flow through hollow organs.

Striated Muscle Tissue

Skeletal Muscle

  • Long, multinucleated cells (fibers), voluntary control, attached to skeleton.

Cardiac Muscle

  • Branched cells, 1-2 nuclei, involuntary control, intercalated discs for coordination.

Smooth Muscle Tissue

  • Spindle-shaped, single nucleus, involuntary, found in hollow organs, connected via gap junctions.

Properties of Muscle Cells

  • Contractility: ability to contract without requiring cell shortening.
  • Excitability: responding to stimuli.
  • Conductivity: conducting electrical changes across membranes.
  • Extensibility: stretching capabilities.
  • Elasticity: returning to original length post-stretch.

Muscle Cell Structure

Myocyte Terminology

  • Sarcoplasm: cytoplasm of myocyte.
  • Sarcolemma: plasma membrane of myocyte.
  • Sarcoplasmic Reticulum (SR): modified ER around myofibrils.

Myofibrils

  • Cylindrical organelles crucial for contraction, packed with specialized proteins.

Myofilaments

  1. Thick filaments: bundles of myosin.
  2. Thin filaments: include actin, tropomyosin, troponin.
  3. Elastic filaments: titin for stabilization.

Sarcomere Structure

  • I band: thin filaments only.
  • Z disc: anchors thin filaments.
  • A band: zone of overlap, both thick and thin filaments.
  • H zone & M line: structures for supporting thick filaments.

Skeletal Muscle Organization

  • Muscle fibers = fascicles =