Mechanotransduction
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Mechanotransduction refers to the many mechanisms by which cells convert mechanical stimulus into chemical activity.[1][2]
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[edit] Ear
One such mechanism is the opening of ion channels in the hair cells of the cochlea in the inner ear.
Air pressure changes in the ear canal cause the vibrations of the tympanic membrane and middle ear ossicles. At the end of the ossicular chain, movement of the stapes footplate within the oval window of the cochlea, in turn, generates a pressure field within the cochlear fluids, imparting a pressure differential across the basilar membrane. A sinusoidal pressure wave results in localized vibrations of the organ of Corti: near the base for high frequencies, near the apex for low frequencies. The cochlea thus acts as an “acoustic prism”, distributing the energy of each Fourier component of a complex sound at different locations along its longitudinal axis.Hair cells in the cochlea are stimulated when the basilar membrane is driven up and down by differences in the fluid pressure between the scala vestibuli and scala tympani. Because this motion is accompanied by a shearing motion between the tectorial membrane and the reticular lamina of the organ of Corti, the hair bundles that link the two are deflected, which initiates mechano-electrical transduction. When the basilar membrane is driven upward, shear between the hair cells and the tectorial membrane deflects hair bundles in the excitatory direction, toward their tall edge. At the midpoint of an oscillation the hair bundles resume their resting position. When the basilar membrane moves downward, the hair bundles are driven in the inhibitory direction.
Basilar Membrane motion causes a shearing motion between the reticular lamina and the tectorial membrane, thereby activating the mechano-sensory apparatus of the hair bundle, which in turn generates a receptor potential in the hair cells.
[edit] Skeletal Muscle
When a deformation is imposed on a muscle, changes in cellular and molecular conformations link the mechanical forces with biochemical signals, and the close integration of mechanical signals with electrical, metabolic, and hormonal signaling may disguise the aspect of the response that is specific to the mechanical forces.[3]
[edit] References
- ^ Integrins in Mechanotransduction - Katsumi et al. 279 (13): 12001 - Journal of Biological Chemistry
- ^ Mechanical Strain Induces pp60[IMAGE] Activation and Translocation to Cytoskeleton in Fetal Rat Lung Cells - Liu et al. 271 (12): 7066 - Journal of Biological Chemistry
- ^ Burkholder, Thomas J. (2008). "Mechanotransduction in skeletal muscle". Front Biosci. 12: 174–191.. ISSN PMC2043154.
- Mammano, F. and R. Nobili, Biophysics of the cochlea: linear approximation. J Acoust Soc Am, 1993. 93(6): p. 3320-32.
- von Bekesy, G., DC resting potential inside the cochlea partition. J Acoust Soc Am, 1952. 24: p. 72-76.
- 1. Kandel, E.R., Schwartz, J.H., Jessell, T.M., Principles of Neural Science. New York: McGraw-Hill ed, ed. 4th. 2000.
- A. J. Hudspeth, Y. Choe, A. D. Mehta, and P. Martin, Putting ion channels to work: Mechanoelectrical transduction, adaptation, and amplification by hair cells, PNAS, October 24, 2000; 97(22): 11765 - 11772.
- A. J. Hudspeth, Nature 341, 397 (1989).
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