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 –Meissner’s 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 –Meissner’s 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. Abram’s Left EyeProf. Abram’s 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 Meniere’s 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?