human Sensory Apparatus
Taste
- Total number of human taste buds (tongue, palate, cheeks) = 10,000
- Number of taste buds on the tongue = 9,000
- Height of taste bud = 50-100 microns (From: Farbman, A.I., Taste Bud, in G. Adelman, eds., Encyclopedia of Neuroscience, 1987)
- Diameter of taste bud = 30-60 microns (From: Farbman, A.I.)
- Number of receptors on each taste bud = 50-150 (Boron, W.F. and Boulpaep, E.L., Medical Physiology. A Cellular and Molecular Approach, Philadelphia: Saunders, 2003)
- Diameter of taste receptor = 10 micron
- Diameter of taste fiber = less than 4 micron
- Taste threshold for quinine sulfate = 3.376 mg/liter water
Smell
- Number of human olfactory receptor cells = 12 million (Shier, D., Butler, J. and Lewis, R. Hole's Human Anatomy & Physiology, Boston: McGraw Hill, 2004)
- Number of rabbit olfactory receptor cells = 100 million
- Number of dog olfactory receptor cells = 1 billion
- Number of bloodhound olfactory receptor cells = 4 billion (Shier, D., Butler, J. and Lewis, R. Hole's Human Anatomy & Physiology, Boston: McGraw Hill, 2004)
- Surface area of olfactory epithelium (contains olfactory receptor cells) in humans = 10 cm2 (Bear, M.F., Connors, B.W. and Pradiso, M.A., Neuroscience: Exploring the Brain, 2nd edition, Baltimore: Lippincott Williams and Wilkins, 2001, p. 269)
- Surface area of bloodhound olfactory epithelium = 59 in2 (Shier, D., Butler, J. and Lewis, R. Hole's Human Anatomy & Physiology, Boston: McGraw Hill, 2004)
- Area of olfactory epithelium in some dogs = 170 cm2 (Bear, M.F., Connors, B.W. and Pradiso, M.A., Neuroscience: Exploring the Brain, 2nd edition, Baltimore: Lippincott Williams and Wilkins, 2001, p. 269)
- Area of olfactory epithelium in cats = 21 cm2 (Bradshaw, J., Behavioral biology, in The Waltham Book of Dog and Cat Behaviour, ed. C. Thorne, Oxford: Pergamon Press, 1992)
- Thickness of olfactory epithelium mucous layer = 20-50 microns. (Boron and Boulpaep, 2003)
- Diameter of olfactory receptor axons = 0.1-0.2 micron
- Diameter of distal end olfactory receptor cell = 1 micron
- Diameter of olfactory receptor cell = 40-50 micron
- Number of cilia per olfactory receptor cell = 10-30
- Length of cilia on olfactory receptor cell = 100-150 micron
- Concentration for detection threshold of musk = 0.00004 mg/liter air
Vision
- Length of eyeball (adult) = 24.2 mm (from Riordan-Eva, P. and Whitcher, J.P., Vaughan & Asbury's General Ophthalmology, 17th ed., New York: Lange Medical Books, 2008)
- Length of eyeball (newborn) = 16.5 mm (from Riordan-Eva and Whitcher, 2008)
- Volume of eyeball = 5.5 cm3
- Weight of eyeball = 7.5 g
- Average time between blinks = 2.8 seconds
- Average duration of a single blink = 0.1-0.4 seconds (Schiffman, H.R., Sensation and Perception. An Integrated Approach, New York: John Wiley and Sons, Inc., 2001)
- Thickness of cornea = ~0.5 mm in center; ~1 mm in periphery (Foster, C.S., Azar, D.T. and Dohlman, C.H. Smolin and Thoft's The Cornea. Scientific Foundations and Clinical Practice, 4th edition, Philadelphia: Lippincott Williams & Wilkins, 2005)
- Diameter of cornea = 11.5 mm
- Thickness of lens = 4 mm (from Riordan-Eva and Whitcher, 2008)
- Diameter of lens = 9 mm (from Riordan-Eva and Whitcher, 2008)
- Composition of lens = 65% water; 35% protein (from Riordan-Eva and Whitcher, 2008)
- Nerves in lens = 0 (from Riordan-Eva and Whitcher, 2008)
- Blood vessels in lens = 0 (from Riordan-Eva and Whitcher, 2008)
- Number of retinal receptor cells = 5-6 million cones; 120-140 million rods
- Number of retinal ganglion cells = 800 thousand to 1 million
- Number of fibers in optic nerve = 1,200,000
- Number of neurons in lateral geniculate body = 570,000
- Number of cells in visual cortex (area 17) = 538,000,000
- Wavelength of visible light (human) = 400-700 nm
- Amount of light necessary to excite a rod = 1 photon
- Amount of light necessary to excite a cone = 100 photons
- Location of the greatest density of rods = 20o from fovea
- Highest density of rods = 160,000 per mm2
- Peak density of rods (cat) = 400,000 per mm2
- Density of cones in fovea = 200,000 per mm2
- Diameter of fovea = 1.5 mm
- Intraocular pressure = 10-20 mm Hg
- Volume of orbit = 30 ml
- Area of retina = 2,500 mm2
- Thickness of retina = 120 microns (ranges from 100 to 230 microns)
- Production rate of aqueous humor = 2 microliters/min
- Turnover of aqueous humor = 15 times/day
- % volume of eye occupied by the vitreous = 80%
- Maximal sensitivity of red cones = 570 nm
- Maximal sensitivity of green cones = 540 nm
- Maximal sensitivity of blue cones = 440 nm
- More Facts and Figures about the Human Retina from WebVision.
Touch
- Weight of skin (adult human) = 9 lb.(4.1 kg) (Source: Schiffman, H.R., Sensation and Perception. An Integrated Approach, New York: John Wiley and Sons, Inc., 2001)
- Surface area of skin (adult human) = 3,000 in2 (~1.8 m2) (Source: Schiffman, H.R., Sensation and Perception. An Integrated Approach, New York: John Wiley and Sons, Inc., 2001)
- Number of tactile receptors in the hand = 17,000
- Number of nerve endings in hand = 1,300 per in2
- von Frey threshold (Face) = 5 mg
- 2 point threshold (Finger) = 2-3 mm
- Length of Meissner corpuscle = 90 - 120 micron
- Density of receptors on finger tips = 2,500 per cm2
- Density of Meissner's corpuscles on finger tips = 1,500 per cm2
- Density of Merkel's cells on finger tips = 750 per cm2
- Density of Pacinian corpuscles on finger tips = 75 per cm2
- Density of Ruffini's corpuscles on finger tips = 75 per cm2
- Thermal pain threshold = 45oC
Posts
0 comments:
Post a Comment