Taste Smell and Hearing HCT II

Learning outcomes Describe the anatomy of the nose and the function of each part. Describe how smell sensations are created and interpreted. Describe the anatomy of the tongue and the function of each part. Describe how taste sensations are created and interpreted.

Describe the anatomy of the ear and the function of each part. Explain the role of the ear in maintaining equilibrium. Explain how sounds travel through the ear and are interpreted in the brain. State ways that hearing changes with age.

Introduction Special senses Sensory receptors located in head Nose – smell Tongue – taste Eyes – vision Ears – hearing and equilibrium Touch is a generalized sense Stimulus  nervous system  brain  response

Nose and Sense of Smell Olfactory receptors Chemoreceptors – respond to changes in chemical concentrations Chemicals must be dissolved in mucus Located in the olfactory organ

Nose and Sense of Smell (cont) Smell sensation Activation of smell receptors  information sent to olfactory nerves that send the information along olfactory bulbs and tracts to different areas of the cerebrum; cerebrum interprets the information as a particular type of smell

Nose and Sense of Smell (cont.) Sensory Adaptation Chemical can stimulate receptors for limited time Receptors fatigue and stop responding to chemical No longer smell odor Perfume Test

Very Good! Apply Your Knowledge You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it? ANSWER: After a few minutes, smell receptors undergo sensory adaptation and no longer respond to the chemical, and the patient can no longer smell the odor. Very Good!

Tongue and Sense of Taste Gustatory receptors – located on taste buds Taste buds Location Papillae of the tongue Roof of mouth Walls of throat } fewer than on tongue

Tongue and Sense of Taste (cont.) Taste cells and supporting structures On taste buds Supporting structures fill in space Taste cells Chemoreceptors Chemicals in food and drink must be dissolved in saliva to activate Tongue

Tongue and Sense of Taste (cont.) Spicy foods Activate pain receptors Interpreted by brain as “spicy” Taste sensation 4 primary Sweet – tip Sour – sides Salty – tip and sides Bitter – back Tongue

Back

Apply Your Knowledge Great Job! What are the four primary taste sensations and where are their corresponding taste cells located? ANSWER: The four primary taste sensations are: Sweet – concentrated on the tip of the tongue Sour – concentrated on the sides of the tongue Salty – concentrated on the tip and sides of the tongue Bitter – concentrated on the back of the tongue Great Job!

The Ear and the Senses of Hearing and Equilibrium: Structures External ear Auricle (pinna) Collects sound waves External auditory canal Guides sound wave to tympanic membrane Contains Cerumen (wax) Why do we have wax in our ears? Tympanic membrane Separates external canal and middle ear Vibrates when sound hits it Ear

Sound waves travel through the external auditory canal to the tympanic membrane, also known as the ear drum. The tympanic membrane separates the outer ear from the middle ear. It vibrates when sound waves hit it and sends those sounds to the middle ear.

The Ear and the Senses of Hearing and Equilibrium: Structures (cont.) Middle ear Ear ossicles Malleus Incus Stapes Ossicles vibrate in response to vibration of tympanic membrane Eustachian tube Connects middle ear to throat Equalizes pressure on eardrum Oval window Separates middle ear from inner ear Ear

*** Sound waves cause the ear drum to vibrate, which is amplified or increased by the ossicles. Vibration of the stapes against the oval window causes movement of fluid in the inner ear. Auditory or Eustachian tube: This is a tube that connects the throat to the middle ear. It allows air to enter the middle ear and equalizes pressure in our ears. Why is it common for an infection in our throat to spread to our inner ear?

The Ear and the Senses of Hearing and Equilibrium: Structures (cont.) Inner ear – labyrinth of communicating chambers Semicircular canals – detect balance of the body. This contains a liquid and delicate hair like cells that bend with movement. Impulses are sent from the canals to the vestibular nerve and eventually to the cerebellum of the brain help to maintain our balance. Vestibule – (equilibrium) This acts as a door to the two other parts of the inner ear. Cochlea 2. Cochlea (shaped like a snail): This contains hair like cells that line the organ of corti (receptor of sound waves which carries sound waves from the cochlear nerve to the auditory nerve.) The auditory nerve carries the message to the temporal lobe, which interprets the message as hearing. Hearing receptors Organ of Corti – organ of hearing Ear

Back Back

The Ear and the Senses of Hearing and Equilibrium: Hearing Process Sound waves collected Waves cause tympanic membrane to vibrate Ossicles amplify vibrations, which enter inner ear Movement of hairs lining cochlea trigger nerve impulses Impulses are transmitted by auditory nerve to the brain for interpretation

How hearing works

The Ear and the Senses of Hearing and Equilibrium: Structures (cont.) Head movement causes fluid in semicircular canals and vestibule to move Equilibrium receptors transmit information along vestibular nerves to cerebrum Cerebrum determines if body needs to make adjustments

How to Recognize Hearing Problems in Children Guidelines Infants to 4 months Startled by loud noises Recognize mother’s voice 4 to 8 months Regularly follow sounds Babble at people 8 to 12 months Respond to the sound their name Respond to “no”

The Aging Ear External ear larger / earlobe longer Cerumen dryer and prone to impaction Ear canal narrower Eardrum shrinks and appears dull and gray Ossicles do not move as freely Semicircular canals less sensitive to changes in position – affects balance

Apply Your Knowledge What problem with the aging ear makes the elderly more prone to falls? ANSWER: The semicircular canals become less sensitive to change in position, which affects balance. This problem with equilibrium results in increased chance of falls in the elderly. Great Answer!

Hearing Loss Symptom of a disease, not a normal part of aging Conductive hearing loss Interruption in transmission to inner ear Causes Obstruction of ear canal Infection of middle ear Reduced movement of stirrup Sensorineural hearing loss Sound waves not perceived by brain as sound Causes Hereditary Repeated exposure to loud noises / viral infections Side effect of medication

Infections (otitis): Otitis Media: Otitis Externus

Otitis Interna

Age Related- look the following conditions up and identify the causes, signs and treatments if any. Meniere's Disease Otosclerosis

Common Diseases and Disorders Disorder / Disease Description Cerumen impaction Build up of wax within external auditory canal Hearing loss Deafness Meniere’s disease Disturbance in equilibrium characterized by vertigo and tinnitus

Common Diseases and Disorders Disorder / Disease Description Otitis Otitis externa Otitis media Otitis interna Inflammation of the ear Swimmers’ ear Middle ear infection; common infection Labyrinthitis; inner ear infection Osteosclerosis Immobilization of the stapes; common cause of conductive hearing loss Presbycusis Hearing loss due to aging process

Treating Ear and Hearing Problems Patient education Preventative ear care Administer ear medications Medications and Irrigation Relieve inflammation or irritation of canal Loosen and remove impacted cerumen or foreign body

Treating Ear and Hearing Problems (cont.) Other devices / strategies Amplifiers Closed-captioning Appliances that light up as well as ring Hearing aids Obtaining a hearing aid Otologist – medical doctor specializing in health of ear Audiologist – evaluates and corrects hearing problems Care and use Batteries Routine cleaning Keep dry and avoid hair sprays

Apply Your Knowledge Excellent! F ANSWER: True or False: ___ An audiologist is a physician that specializes in ear health. ___ Otitis media is also called swimmers’ ear. ___ Presbycusis is hearing loss due to the aging process. ___ Vertigo is ringing in the ears. ___ Otitis interna is an inflammation of the labyrinth. ___ Meniere’s disease is characterized by disturbances in equilibrium. ___ Otosclerosis is the immobilization of the stapes. ___ tinnitus is dizziness. otologist F externa T Excellent! F Tinnitus T T T F Vertigo