Musculoskeletal System: Contractile Cells


Contractile cells

The musculoskeletal system consists of the bones, cartilage, muscles, joints, tendons and ligaments in the human body. The musculoskeletal system support the body, allow for motion and protect internal organs. It can be viewed as two separate systems which function together. Cartilage and bone are specialised forms of connective tissue.

Muscle tissue is one of the four basic tissue types. In addition to the three main types of muscle cells, there are three additional contractile cells in the body.

You should be able to:

  • Describe and identify the types of contractile cells, and summarise similarities and differences.
  • Compare the functions of each type of contractile cell.
  • Recognise the ultrastructural appearance of contractile cells.
  • Explain the organisation and layers of connective tissue of muscle tissue.
  • Recognise and distinguish between the three types of muscle tissue in transverse and longitudinal sections.
  • Explain the structure and function of skeletal, cardiac and smooth muscle.
  • Identify the myofibrils and cross-striations in striated muscle fibers.
  • Describe a dense body, desmosome, intercalated discs and gap junctions.
  • Define and describe satellite cells.
  • Define and describe a motor unit.
  • Explain the filament model of muscle contraction.
  • Explain fast and slow muscle fibers.
  • Distinguish between smooth muscle and dense regular connective tissue.

Slides for this week

For each slide, complete the work as listed below. Completing the whole slide will assist you in understanding and retention. For each slide, allocate an A3 spread in your workbook. Remember to add the slide and its page number to the index in the front of the book.


  1. Name the 3 types of muscle cells.
  2. Name and define the striations of skeletal muscle.
  3. What is the unit between two Z-lines termed?
  4. How are individual cardiac muscle cells linked?
  5. Name 2 areas where smooth muscle is found.
  6. Name 3 diseases of muscle.
  7. Why do smooth muscle fibers in cross section have different diameters?
  8. Why do some smooth muscle fibers in cross section fail to show nuclei?
  9. Are myofibrils or sarcomeres present in smooth muscle fibers?
  10. Name and discuss the five types of contractile elements found in the body.
  11. Explain the organization, function and structure of skeletal, cardiac and smooth muscle.
  12. Identify and explain the connective tissue associated with muscle cells and fascicles of muscle cells.
  13. Compare and contrast skeletal, cardiac and smooth muscle with regards to structure and function.
  14. Identify skeletal, cardiac and smooth muscle on a slide and in various tissues and organs.
  15. Describe how muscles contract and relax.
  16. Explain the relationship between muscle and the nervous system and how this relates to exercise and muscle performance.
  17. Define, explain and identify a motor unit and its component parts.
  18. Describe, identify and understand the sarcomere and how this relate to muscle striations.
  19. Identify the intercalated disks in cardiac fibers.
  20. Discuss the similarities and difference between smooth muscle fibers and collagen fibers of connective tissue.
  21. Complete the table, listing important differences between the 3 muscle types:
Skeletal Cardiac Smooth
Motor control

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