Special Senses

• Eye – the organ used to sense light
• Outer layer of the eye consists the sclera and cornea
• Middle layer of the eye consists the choroid, ciliary body and iris
• Inner layer of the eye consists of retina
• Sclera is also called as scleroid layer
• Sclera – (white of eye) a tough protective layer of connective tissue that helps maintain the shape of the eye and provides an attachment for the muscles that move the eye
• Cornea - the clear, dome-shaped part of the sclera covering the front of the eye through which light enters the eye
• Anterior Chamber – a small chamber between the cornea and the pupil
• Aqueous Humor - the clear fluid that fills that anterior chamber of the eye and helps to maintain the shape of the cornea providing most of the nutrients for the lens and the cornea and involved in waste management in the front of the eye
• Choroid Layer - middle layer of the eye containing may blood vessels
• Ciliary Body - is a circular band of muscle that is connected and sits immediately behind the iris
• ciliary body produces aqueous humor, changes shape of lens for focusing
• Iris - the pigmented front portion of the choroid layer and contains the blood vessels
• Iris - determines the eye color and it controls the amount of light that enters the eye by changing the size of the pupil
• Lens - a crystalline structure located just behind the iris
• Lens - focuses light onto the retina
• Pupil - the opening in the center of the iris
• Pupil - changes size as the amount of light changes (the more light, the smaller the hole)
• Vitreous - a thick, transparent liquid that fills the center of the eye
• Vitreous - is mostly water and gives the eye its form and shape (also called the vitreous humor)
• Optic nerve - the nerve that transmits electrical impulses from the retina to the brain
• myopia or nearsightedness is where the eyeball is too long or the cornea is too steep
• hyperopia or far sightedness where the eyeball is short or lens cannot become round enough
• cataracts where the lens becomes fogged
• presbyopia where the muscles controlling the bulging of the lens become weak as we age
• nyctalopia or night blindness where vision is impaired in dim light and in the dark due to pigment rhodospin in the rods not functioning properly
• the cornea and the lens help to produce the image on the retina
• images formed by the lens are upside down and backwards when they reach the retina
• Fovea – point of central focus great density of cones and center of the eye's sharpest vision and the location of most color perception
• Outer Ear & ear canal – brings sound into eardrum
• Eardrum – vibrates to amplify sound & separates inner and middle ear
• Middle ear has 3 small bones or Ossicles = anvil, stirrup, stapes
• Eustachian tube – connects middle ear to throat and equalizes pressure on eardrum
• Cochlea – in inner ear and has receptors for sound & sends signals to brain via Auditory Nerve
• The mouth contains around 10,000 taste buds, which detect different tastes.
• The five primary tastes: are Sour, Sweet, Bitter, Salty, Umami
• Umami - salts of certain acids (for example monosodium glutamate or MSG)
• Each of your taste buds contains 50-100 specialised receptor cells.
• Your skin and deeper tissues contain millions of sensory receptors
• Light touch - Meissner's corpuscles are enclosed in a capsule of connective tissue