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6:7 Special Senses
Senses allow body to react to the environment
Enable us to see, hear, taste, smell, and to maintain balance
5 senses
Sight
Hearing
Tasting
Smelling
Touching
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Eye ~ Sense of Sight
In order for vision to take place:
Light rays are transmitted to the optic nerve
Optic nerve relays information to brain for interpretation
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Layers of the Eye
Sclera: outermost layer of the eye
Choroid coat: middle layer of the eye
Retina: innermost layer of the eye
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4. Other Special Structures
Conjunctivia: membrane that lines the eyelid and cover the front of the eye
Cornea: Transmits & focuses light into the eye
Iris: colored portion of the eye
Pupil: black area of the iris
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Lens: focuses light rays on the retina
Aqueous humor: Clear fluid that fills the space between the cornea & iris
Vitreous humor: Jelly-like substance that fills the area behind the lens and maintains the round shape of the eye
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6. Diseases and Abnormal Conditions
Amblyopia: “lazy eye”; seen in childhood. One eye is dominant over the other
Astigmatism: abnormal curvature of the cornea; causes blurred vision
Cataract: clouding of the lens of the eye
Conjuctivitis: pink eye
Glaucoma: increased pressure in the eye; usually seen in people over 40
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7. Diseases and Abnormal Conditions (continued)
Hyperopia – farsightedness
Myopia – nearsightedness
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Controls hearing and balance
Sound waves transmitted to the auditory nerve which relays information to the brain for interpretation
Consists of the outer ear, middle ear, and inner ear
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Outer Ear
Pinna or auricle: outer part of the ear
Auditory canal: tube that leads to the inner ear
Tympanic membrane: ear drum
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Middle Ear
3 small bones of the middle ear
Malleus
Incus
Stapes
Eustachian tube: connects the ear to the throat
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Sense of Taste
Taste receptors located on the tongue
Four main tastes
Sweet
Salty
Sour
Bitter
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Sense of Smell
Nose is the organ of smell
Olfactory receptors in nasal cavity carry impulses from the olfactory nerve to the brain for interpretation
Humans can detect over 6,000 smells
Sense of taste and smell related
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13. Skin and General Senses
Sense receptors for pressure, heat, cold, touch, and pain located in the skin and connective tissue
Allow the human body respond to its environment
Help body react to conditions that could cause injury
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