THE EARAnd 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 EARThe outer ear

collects sound and funnels it to the eardrum.

In the middle ear, the sound waves hit the eardrum and move the hammer, 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 is 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 differenceIntensitymemories

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 BabiesMonkeysInfant allowed to see, hear, smell (but not touch) become desperately unhappy

Skin sensations are a variation of the basic 4PressureWarmthColdPain

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 articlehttp://www.nytimes.com/2012/11/18/magazine/ashlyn-blocker-feels-no-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 SweetSourSaltyBitter

200 taste budsReproduce every 1 or 2 weeksOlder= decrease in taste budsSmoking and Alcohol= decrease in taste buds

THE SURVIVAL FUNCTIONS OF BASIC TASTES

Taste IndicatesSweet Energy source

Salty Sodium essential to physiological processes

Sour Potentially toxic acid

Bitter Potential poisons

Umami 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 odorsDecreases with ageHave 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

Receptor cells inolfactory membrane

Nasal passage

Olfactorybulb

Olfactorynerve

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.

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