Lecture on Muscle Types

Overview

• Focus on structural and functional differences between:
  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Key characteristics to identify from microscope images
• Important terminology:
  • Multinucleate: Several nuclei within a cell
  • Uninucleate: One nucleus per cell
  • Striated: Stripy appearance
  • Non-striated: No stripy appearance
  • Cell shapes: Branch, cylindrical, and spindle
  • Contraction speed: slow, intermediate, fast

Skeletal (Voluntary) Muscle

• Function: Movement of bones/joints/limbs under conscious control
• Appearance:
  • Striated (bands of actin and myosin)
  • Multinucleate
  • Cylindrical cells
• Contraction: Fast and rapid

Cardiac Muscle

• Function: Makes the heart contract, myogenic (self-initiating contraction)
• Location: Heart
• Appearance:
  • Striated (less distinct than skeletal)
  • Uninucleate
  • Branch cells with interlocking junctions
• Contraction: Intermediate speed and length

Smooth (Involuntary) Muscle

• Function: Controls involuntary actions (e.g., peristalsis, bronchial diameter, pupil size)
• Appearance:
  • Non-striated
  • Uninucleate
  • Spindle-shaped cells
  • No regular arrangement
• Contraction: Slow and sustained

Study Tips

• Venn Diagram: Draw and fill in to understand similarities/differences
• Microscope Images: Be able to identify muscle types from images
  • Cardiac muscle: interlocking junctions
  • Skeletal muscle: obvious striations
  • Smooth muscle: spindle-shaped cells

Final Advice

• Use precise scientific terminology in exams
• Avoid generic terms like "it," "they," "amount," and "size"