The Senses of the Nervous System There are five general categories of sensory receptors: pain receptors, thermoreceptors, mechanoreceptors, chemoreceptors, and photoreceptors.
The Eye Pupil - small opening in the middle of the iris through which light enters the eye Lens - transparent object behind the iris that changes shape to help adjust the eye’s focus to see near or distant objects Retina - innermost layer of the eye Cornea – tough, clear covering that protects the eye and allows light to pass through Humor – fluids that maintain the shape of the eye Iris – colored part of the eye that controls how much light enters Rod - photoreceptor in eye that is extremely sensitive to light Cones - in the retina of the eye, a photoreceptor that responds to light of different colors, producing color vision
Eye
The Ear (Hearing and Balance) Auditory Canal – ear canal, where sound enters Tympanum – Ear Drum, vibrates as sound wave hit it Cochlea - fluid-filled part of the inner ear; sends nerve impulses to the brain through the cochlear nerve Ear bones Hammer Anvil Stirrup Eustachian tube – equalizes pressure between environment and inner ear Oval window – sends waves of pressure to cochlea Balance semicircular canal - one of three structures within the inner ear that help an organism maintain balance (oriented perpendicular to each other)
Ear
Semicircular Canals
Smell and Taste Chemoreceptors – receptors which sense different Chemicals Taste and smell are linked closely together “Hold your Nose” taste bud - sense organ that detects the flavor of a substance
Touch Related Senses Touch – Mechanoreceptors Temperature – Thermoreceptors Pain – Pain Receptors
Questions Name the five types of sensory receptors and list where they are found in the body. Identify the parts of the eye and the function of each part. What parts of the ear are responsible for hearing? For balance? Explain why you can’t “taste” food when you have a bad cold. Why do you feel dizzy after spinning around? How can a dancer or ice skater do lengthy spins?