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Unit 8: The Senses The Senses DB • Explain why the smell of a doctor�s office or the smell of turkey cooking on Thanksgiving can easily generate an emotional response. Hint: there is a concept called sense memory that should be referenced here. OR The ear is important in not only hearing, but balance. Explain how the ear functions, and how it can be easily damaged by loud noises, and result in hearing loss. OR How do we perceive color? Why does the color wash out when we look at a bright light, or are out in the sun? Responsibilites for the week • • • • • • • • • Work on APT project. Writing paper!! Lesson 1: Sense Organs Lesson 2: The Eye Lesson 3: The Ear The Senses: Quick Wrap-Up Unit 8 Practice Quiz Discussion Seminar The Senses Module Exam LEARNING OUTCOMES • HS120-U8-1 general. Classify sense organs as special or HS120-U8-2 Describe the general sense organs and their functions. HS120-U8-3 eye. Identify the structures and functions of the HS120-U8-4 Identify the structures functions of the ear. HS120-U8-5 Discuss the physiology of hearing. 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 Sound is: A pressure disturbance (alternating areas of high and low pressure) originating from a vibrating object 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 Posterior wall right eye of Rods only Less cones cones Macula Lutea Mostly Cones Fovea Centralis ONLY Cones Detailed color vision cones Pg 56 3 Optic Disc Lateral to ML. Radiate s Blood V. The Retina: Photoreceptors • Rods: – Respond to dim light – Are used for peripheral vision – Ex. Best to see moonlit evening when you don’t look directly at object. Recognize best when they move. Peripheral. • Cones: – – – – Respond to bright light Have high-acuity color vision Are found in the macula lutea Are concentrated in the fovea centralis The Retina: Ganglion Cells and the Optic Disc Focusing Light on the Retina; Pathway of light entering the eye: • • • • • • • • Light is Refracted cornea Refracted again aqueous humor Lens Refracted again vitreous humor the neural layer of the retina to the photoreceptors Major visual disorders • Refraction disorders – Myopia = nearsightedness • • • • • • Astigmatism = irregularity in cornea or lens Conjunctivitis = pink eye Strabismus = convergent Cataracts=? Macular Degeneration=? Glaucoma=? Eye anatomy • • • • • • • • • Sclera Choroid Retina Iris Conjunctiva Lacrimal gland Pupil Lens Ciliary Muscles 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 PATH: Transmission of Sound to the Inner Ear Sound and Mechanisms of Hearing • Sound vibrations beat against the eardrum • The eardrum pushes against the ossicles, which presses fluid in the inner ear against the oval and round windows – This movement sets up shearing forces that pull on hair cells – Moving hair cells stimulates the cochlear nerve that sends impulses to the brain Deafness • Conduction deafness – something hampers sound conduction to the fluids of the inner ear (e.g., impacted earwax, perforated eardrum, osteosclerosis of the ossicles) • Sensorineural deafness – results from damage to the neural structures at any point from the cochlear hair cells to the auditory cortical cells 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 areas for taste receptors Sour Bitter POSTERIOR TONGUE Sour Bitter Sour Bitter salty salty salty salty salty Sweet -tip ANTERIOR TONGUE salty Taste Sensations • There are five basic taste sensations – Sweet – sugars, saccharin, alcohol, and some amino acids – Salt – metal ions – Sour – hydrogen ions – Bitter – alkaloids such as quinine and nicotine – Umami – elicited by the amino acid glutamate Influence of Other Sensations on Taste • Taste is 80% smell • Thermoreceptors, mechanoreceptors, nociceptors also influence tastes • Temperature and texture enhance or detract from taste 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?