Orientation and Gravity

Orientation and Gravity - circular zone near the edge of...

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Orientation and Gravity Orientation and gravity are detected at the semicircular canals. Hair cells along three planes respond to shifts of liquid within the cochlea, providing a three-dimensional sense of equilibrium. Calcium carbonate crystals can shift in response to gravity, providing sensory information about gravity and acceleration. Photoreceptors Detect Vision and Light Sensitivity The human eye can detect light in the 400-700 nanometer (nm) range, a small portion of the electromagnetic spectrum, the visible light spectrum. Light with wavelengths shorter than 400 nm is termed ultraviolet (UV) light. Light with wavelengths longer than 700 nm is termed infrared (IR) light. Eye In the eye, two types of photoreceptor cells are clustered on the retina , or back portion of the eye. These receptors, rods and cones , apparently evolved from hair cells. Rods detect differences in light intensity; cones detect color. Rods are more common in a
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Unformatted text preview: circular zone near the edge of the eye. Cones occur in the center (or fovea centralis ) of the retina. Light reaching a photoreceptor causes the breakdown of the chemical rhodopsin , which in turn causes a membrane potential that is transmitted to an action potential. The action potential transfers to synapsed neurons that connect to the optic nerve. The optic nerve connects to the occipital lobe of the brain. Humans have three types of cones, each sensitive to a different color of light: red, blue and green. Opsins are chemicals that bind to cone cells and make those cells sensitive to light of a particular wavelength (or color). Humans have three different form of opsins coded for by three genes on the X chromosome . Defects in one or more of these opsin genes can cause color blindness, usually in males....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Orientation and Gravity - circular zone near the edge of...

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