Smooth Muscle Tissue

(The cells have been teased apart to see them better)

Key:

  1. Teased smooth muscle cells
  2. Nucleus of a smooth muscle cell
  3. A single smooth muscle cell

Description:

  • This muscle tissue is called smooth muscle because it lacks striations (stripes)
  • The organization of the myofilaments in smooth muscle is not as orderly as in the striated varieties.
  • The cells are spindle shaped
  • Each cell has one nucleus located in the center of the cell
  • The cells are arranged into sheets
  • This tissue is involuntarily controlled, meaning we do not have conscious control over this tissue.

Function:

  • These cells are able to contract even if they are greatly stretched (due to the arrangement of the myofilaments)
  • Propels substances down tubes
  • Changes the diameter of tubes

Location:
Walls of hollow organs:

  • Digestive organs
  • Respiratory tree
  • Blood vessels
  • Ureters and urinary bladder
  • Reproductive system (uterus, etc.)