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The skin weighs an average of 4 kg (8.8 lb), covers an area of about 2 m 2 (22 sq ft), and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. [1] The two main types of human skin are glabrous skin, the nonhairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. [16]
The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. [1] The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. [3]
M cones make up about a third of cones in the human eye. The third type responds the most to blue short-wavelength light, peaking at 420 nm, and make up only around 2% of the cones in the human retina. The three types have peak wavelengths in the range of 564–580 nm, 534–545 nm, and 420–440 nm, respectively, depending on the individual.
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in ...
The elements composing the layer of rods and cones ( Jacob's membrane) in the retina of the eye are of two kinds, rod cells and cone cells, the former being much more numerous than the latter except in the macula lutea . Jacob's membrane is named after Irish ophthalmologist Arthur Jacob, who was the first to describe this nervous layer of the ...
The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue guarding muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals ' skin, and it is very similar to pig skin. Though nearly all human skin is covered ...
Specialty. Dermatology. Albinism is a congenital condition characterized in humans by the partial or complete absence of pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as photophobia, nystagmus, and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers.
Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 92 million rod cells (vs ~6 million cones) in the ...