Transcript The ear
THE EAR And other senses LET’S TEST YOUR HEARING…. https://www.youtube.com/watch?v=G-88Vzj0AlA SENSE 2: HEARING (AUDITION) The loudness of a sound is determined by a waves amplitude (height.) The frequency, number of complete wavelengths that pass a point in a given time, determines the sounds pitch: the tones highness or lowness. HEARING THRESHOLD Hearing is measured in decibels. Zero decibels is considered the threshold of hearing. PARTS OF THE EAR Outer Ear: Job: Gather sound waves to eardrum. Parts: auditory canal and eardrum. Middle Ear Job: To Amplify and concentrate the vibrations onto cochlea’s oval window. Parts: Ossicles, made up of three tiny bones: hammer, anvil, and stirrup (malleus, incus, and stapes) Inner Ear Job: To change sound waves into neural impulses Parts: Oval Window, Cochlea, Basilar Membrane, Hair Cells. PROCESS OF HEARING 1. Your outer ear channels sound waves to the eardrum or tympanum. 2. Your eardrum vibrates with sound waves 3. This causes 3 tiny bones called the ossicles (the hammer, anvil and the stirrup) of your middle ear to vibrate PROCESS OF HEARING 4. The vibrating stirrup pushes against the oval window of the cochlea in the inner ear. The cochlea is fluid filled and waves are created. 5. Inside the cochlea is a basilar membrane with hair cells that are bent by the vibrations and are transduced into a neural impulse SOUND WAVES REACH THE In the middle ear, the sound waves hit outer ear EAR The the eardrum and move the hammer, collects sound and funnels it to the eardrum. anvil, and stirrup in ways that amplify the vibrations. The stirrup then sends these vibrations to the oval window of the cochlea. In the inner ear, waves of fluid move from the oval window over the cochlea’s “hair” receptor cells. These cells send signals through the auditory nerves to the temporal lobe of the brain. PROCESS OF HEARING 6. Hair cells synapse with auditory neuron whose axons form the auditory nerve 7. The auditory nerve transmits sound messages though your medulla, pons and thalamus to the auditory cortex of the temporal lobe. What cell triggers neural impulses in the eye? INNER EAR AND VESTIBULAR SENSE The semicircular canals are connected to the cochlea by the vestibular sacs. The semicircular canals contain substance that move when our head rotates or tilts and allows us to maintain our vestibular sense: sense of our body movement and position THE MAN WHO LOST HIS BODY https://www.youtube.com/watch?v=bGlZpZgwnAc HOW DO WE PERCEIVE PITCH: 2 THEORIES Helmholtz’s Place Theory: argues we hear different pitches because different sound waves trigger activity at different places in the cochlea’s membrane…easily explains high pitches since these pitches are highly localized. Frequency Theory: We sense pitch by the basilar membrane in cochlea vibrating at the same rate as the sound. Explains low pitch well…. Volley Principle- alternate firing to get over 1000 fires per sound HOW DO WE LOCATE SOUNDS Why is Having 2 Ears Important? PARALLEL PROCESSING Just like with vision, audition involves parallel processing Time difference Intensity memories HEARING LOSS Conductive Hearing Loss: hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea like eardrum and ossicles. Solution to Conductive Hearing Loss? Hearing aid HEARING LOSS Sensorineural Hearing Loss: damage caused to cochlea’s receptor cells (hair cells) or auditory nerves. Solution? Cochlear Implant OLDER PEOPLE SUFFER MOST HEARING LOSS WITH HIGH FREQUENCY SOUNDS TOUCH Premature Babies Monkeys Infant allowed to see, hear, smell (but not touch) become desperately unhappy Skin sensations are a variation of the basic 4 Pressure Warmth Cold Pain SENSE #3: TOUCH Pain Is a Good Thing! Gate Control Theory: theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain “gate” opened by the activity of pain signals traveling up small nerve fibers “gate” closed by activity in larger fibers or by information coming from the brain SOCIAL INFLUENCE ON PAIN -Pain is both a physiological and a psychological phenomenon. -Depending on symptoms, doctors may use drugs, surgery, etc. or relaxation training, thought distraction. Example: Lamaze Method https://www.youtube.com/watch?v=7ZRYiOa5lM8 MEMORIES OF PAIN More to our memories of pain than the pain we experienced. People tend to overlook duration of pain and instead concentrate on its peak moments and how much pain they felt at the end. What do doctors do because of this? Taper down procedures GIRLS BORN WITHOUT PAIN RECEPTORS https://www.youtube.com/watch?v=J2ECNZA60XE – 5 minute video Ashlyn Blocker article http://www.nytimes.com/2012/11/1 8/magazine/ashlyn-blocker-feelsno-pain.html?_r=2 SENSES 4 & 5: TASTE AND SMELL Why are Taste and Smell studied together? Why are taste & smell studied together? TASTE 4 Basic Sensations Sweet Sour Salty Bitter 200 taste buds Reproduce every 1 or 2 weeks Older= decrease in taste buds Smoking and Alcohol= decrease in taste buds THE SURVIVAL FUNCTIONS OF BASIC TASTES Taste Sweet Salty Sour Bitter Umami Indicates Energy source Sodium essential to physiological processes Potentially toxic acid Potential poisons Proteins to grow and repair tissue TASTE AND SMELL Taste and Smell are both chemical senses. Tongue is central muscle for taste which contain taste buds. Smell runs through receptor cells in nasal cavity which send neural signals to the olfactory bulbs in the brain. SMELL 5 million receptor cells at the top of your nasal cavity Detect 10,000 odors Decreases with age Have your own chemical signature SMELL Nasal Cavity brings the smell up to your receptors Receptor cells send the message to the brain’s olfactory bulb Then to the temporal lobe’s primary smell cortex Parallel Processing Olfactory nerve Olfactory bulb Nasal passage Receptor cells in olfactory membrane SMELL AND EMOTION Sense of smell activates areas in limbic system involved in emotion and memory. Smells can often evoke memories of the past or emotional experiences more often than most other senses. SENSORY RESTRICTION People born without access to a sense, compensate with development of stronger other senses. Sensory Restriction has produced mixed results depending on context: Early Experiments: disorientation, hallucinations, etc. KINESTHESIA – SYSTEM FOR SENSING THE POSITION AND MOVEMENT OF INDIVIDUAL BODY PARTS SUMMARIZING THE SENSES SENSORY SYSTEM SOURCE RECEPTORS Vision Light waves striking the eye Rods and cones in the retina Hearing Sound waves striking the outer ear Cochlear hair cells in the inner ear Touch Pressure, warmth, cold, pain on skin Skin receptors detect pressure, warmth, cold, and pain Taste Chemical molecules in the mouth Basic tongue receptors for sweet, sour, salty, bitter, and umami Smell Chemical molecules breathed in through the nose Millions of receptors at top of nasal cavity Body Position – kinesthesia Any change in position of a body part, interacting with vision Kinesthetic sensors all over the body Body Movement – vestibular sense Movement of fluids in the inner ear caused by head/body movement Hairlike receptors in the semicircular canals and vestibular sacs