Cilia and Flagella

Cilia are tiny hairlike structures that project from the surface of a cell and, like the coordinated action of rowers in a boat, stroke in unison. Cilia in the human body are found on the apical surface (the surface facing the lumen, or cavity) of stationary epithelial cells in the respiratory and female reproductive tracts. In the respiratory system, the cilia transport strands of mucus to the pharynx (throat), where the mucus can either be swallowed or expectorated. In the female reproductive tract, ciliary movements in the epithelial lining of the uterine tube draw the ovum (egg) into the tube and move it toward the uterus.

Fox: Human Physiology, I 3. Cell Structure and I Text I I © The McGraw-Hill

Eighth Edition Genetic Control Companies, 2003

Cell Structure and Genetic Control 55

Microvilli

Flagella And Cilia

Microtubules

Microtubules

■ Figure 3.5 Electron micrographs of cilia. The cilia can be seen in (a) a scanning electron micrograph and (b) cross sections in a transmission electron micrograph. Notice the characteristic "9 + 2" arrangement of microtubules in the cross sections.

Sperm cells are the only cells in the human body that have flagella. The flagellum is a single whiplike structure that propels the sperm cell through its environment. Both cilia and flagella are composed of microtubules (thin cylinders formed from proteins) arranged in a characteristic way. One pair of micro-tubules in the center of a cilium or flagellum is surrounded by nine other pairs of microtubules, to produce what is often described as a "9 + 2" arrangement (fig. 3.5).

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Responses

  • Gilly
    How do cilia transport mucus to the throat?
    8 years ago
  • kristiina
    How is flagella like human actions?
    7 years ago
  • tomacca
    What cells in the human body employ cilia and flagella?
    6 years ago
  • Kelly
    Where on the human body is the cilia and flagella found?
    3 years ago
  • marko gloeckner
    Do viruses have cilia and flagella?
    2 years ago
  • SM
    What the flagella are present in our body?
    2 years ago
  • fnan
    Where is cilia present in human body?
    2 years ago
  • virginia
    Does female have flagellum?
    2 years ago
  • Claire
    Do viruses have flagellums?
    2 years ago
  • Melissa Marcelo
    Is sperm the only flagella in human body?
    8 months ago
  • Alice
    Where is cilia and flagella present in human?
    3 months ago
  • Faruz
    What do flagellum and cilium do in human cells with the centriome?
    1 month ago
  • jessica
    Which human cell has flagellum?
    14 days ago

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