Unit 8: The Senses Amy J. Hilbelink, Ph.D. Tracy Abram, MAIS The Senses Objectives Classify sense organs as special or general. Discuss their functions. Discuss how a stimulus is converted into a sensation. List major senses Describe eye and ear anatomy Describe major visual disorders and hearing impairment Classify sense organs as special or general Special: Eye Taste buds Ear Nose General: Microscopic receptors Pacinian corpuscles Meissners corpuscles Muscle spindles What is the difference between special and general sense organs? The differences Special = they have large and complex organs or localized groupings of specialized receptors like taste buds on tongue. These are the senses that you typically think of; except for perhaps touch! A very special sense The differences General = made of microscopic receptors widely distributed throughout the body. Pacinian corpuscles = pressure and high frequency Meissners corpuscles = fine touch and low frequency Muscle spindles = propriocetors (muscle length and location) Sense organ functions Vision Hearing Smell Taste Balance How is a stimulus converted into a sensation? Stimulus detected [sound] Stimulus converted to electrical signal or nerve impulse= [middle ear] Signal transmitted over nervous system pathway = [VIII cranial nerve] Sensation perceived in brain = [music] music Eye anatomy Sclera Choroid Retina Iris Conjunctiva Lacrimal gland Pupil lens My Eye Exam 2011 Prof. Abrams Left EyeProf. Abrams Right Eye Prof. Abram OTC Scan Eye anatomy Sclera = white of the eye (cornea) Choroid = contains a dark pigment to prevent scattering of light rays Retina = innermost layer of eyeball (rods and comes) Iris = circular colored part of eye Conjunctiva = mucous membrane that lines eyelids and covers the sclera Lacrimal gland = tear duct Pupil = black center of iris; a hole Lens = ciliary muscles contract the lens for focusing Ear anatomy External ear External auditory canal Tympanic membrane eardrum Ear anatomy Middle ear Ear bones = ossicles Malleus Incus stapes Auditory or Eustachian tube Ear anatomy Inner ear Bony labrinth Perilymph Vestibule Semicircular canals Cochlea Crista ampullaris Organ of Corti Major visual disorders Refraction disorders Myopia = nearsightedness Astigmatism = irregularity in cornea or lens Conjunctivitis = pink eye Strabismus = convergent Hearing impairment Blockage of external auditory canal Otosclerosis = structural irregularities in stapes Tinnitus = ringing in ears (may be symptom of otosclerosis) Otitis = ear infection Menieres disease = chronic inner ear disease, resulting in vertigo Which one would be the worst to lose? Have you any questions? Do you have any questions? Are there any questions? Can I answer anything? Can I answer anything for anybody? Is anything unclear? Is everything clear?