photoreception


photoreception

Biological responses to stimulation by light, most often referring to the mechanism of vision. In one-celled organisms such as the amoeba, the whole cell may be sensitive to light. Earthworms have photoreceptive cells scattered over their bodies to help orient themselves by comparison of light intensities in different directions. Most animals have localized photoreceptors of varying complexity. In humans, photoreception relies on the chemical response of a light-sensitive pigment, rhodopsin, in photoreceptor cells in the retina of the eye. Stimulation of those cells results in a stimulus being conducted toward the nervous system. Humans, like other vertebrates, have two types of photosensitive cells, rod cells and cone cells. Rod cells are responsible for vision when there is little light; cone cells mediate daylight vision and colour. Photoreception also refers to photosynthesis in plants. See also sense.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on photoreception, visit Britannica.com.

Seen & Heard

What made you look up photoreception? Please tell us what you were reading, watching or discussing that led you here.

Get Our Free Apps
Voice Search, Favorites,
Word of the Day, and More
Join Us on FB & Twitter
Get the Word of the Day and More