Chapter 6 Hearing, Balance, Taste, and Smell

1st step of general physiological sensation-perception pathway

Physical Stimulus

2nd step of general physiological sensation-perception pathway

Sensory Receptors

3rd step of general physiological sensation-perception pathway

Transduction

4th step of general physiological sensation-perception pathway

Neural Transmission to CNS

5th step of general physiological sensation-perception pathway

Brain Processing

6th step of general physiological sensation-perception pathway

Perception

Transduction

Physical/chemical energy is transformed into electrical signals that nervous system can process

Perception

The conscious interpretation and awareness of the sensory input, influenced by attention, memory, and expectations

Two main parts of sound waves

Amplitude and frequency

Amplitude

height of wave (loudness)

Frequency

cycles per second (pitch)

What makes up the outer ear?

pinna and ear canal

function of pinna and ear canal (outer ear)

Captures, focuses, and filters sound via its shape

What makes up the middle ear?

tympanic membrane and ossicles

function of tympanic membrane and ossicles (middle ear)

Concentrates sound energy (vibrations)

function of two small muscles in middle ear (tensor tympani and stapedius)

Contracts to stiffen chain of ossicles, reducing loudness of sounds

What makes up the inner ear?

cochlea and vestibular system

function of cochlea

place of transduction for hearing

function of vestibular system

helps with sense of balance and planning body movement

Auditory neurons have a preferred _________, but also respond to neighboring __________(S), called the tuning curve

frequency

1st step of auditory pathways into and through brain

orienting response (brainstem)

2nd step of auditory pathways into and through brain

Thalamus (midbrain)

3rd step of auditory pathways into and through brain

Primary auditory cortex (temporal lobe)

4th step of auditory pathways into and through brain

Auditory association cortex (temporal lobe)

What are the 2 theories for coding pitch?

Place coding theory and temporal coding theory

Place coding theory

Pitch determined by location of activated hair cell

Temporal coding theory

Frequency is encoded in rate of firing of auditory neurons

What do hearing aids do?

Amplifies sound

What do cochlear implants do?

stimulates auditory nerves inside cochlea with electrodes

Damage to auditory association cortex in temporal lobe leads to?

auditory agnosia

Agnosia

inability to recognize familiar objects, people, or sounds

Phonagnosia

inability to recognize voices

__________ changes neuron responsiveness

Experience

parts of the vestibular system

semicircular canals, utricle, saccule

Utricle

detects horizontal linear acceleration and head tilt (left/right, forward/backwards)

Saccule

detects vertical linear acceleration and head tilt (up/down)

How does the uitricle and saccule work?

based on gravity effect on otolith crystals in fluid

How many semicircular canals are there?

three

Fluid physically moves the _____ on hair cells

cilia

function of semicircular canals

can track head movement around each of three axes

Vestibular system axons make up this cranial nerve

Vestibular cranial nerve

Sensory conflict theory

motion sickness is result of mismatch between visual info and vestibular system

Tastants

physical stimulus for taste

Papillae

bumps on tongue that contain taste buds

_____ kinds of papillae have different taste sensitivities but respond to all tastes

three

What are the receptors for taste exactly?

taste cells

Each taste bud contains how many taste cells?

50-150

Life span of taste cells

10-14 days

5 basic tastes

sweet, sour, salty, bitter, umami

Explanation for salty and sour taste

Stimulated by simple ions acting via ion channels in taste cell membranes

Salty taste mechanisms

Na+ from salty foods enter via Na+ channels and K+ and Ca2+ from food activate a second salt receptor

Sour taste mechanism

Sour tastants activate a proton selective "sour" receptor ion channel that directly depolarizes cell

More sour = ____ ______

more acidic (release hydrogen ions)

Sweet, bitter, and umami all use this type of receptor

Metabotropic

Sweet tastants and bitter tastants activate different _________

receptors

Bitterness signals what?

presence of toxins

Bitter-sensing taste cells respond _______ to almost any bitter tastant

broadly

Umami tastants are detected by what?

some similar receptors of other tastants and mGluR (metabotropic glutamate receptor)

There is a labeled-line system for each of the _ _____ __ _____

5 kinds of taste

Physical stimulus for smell

chemical olfactants

olfactory epithelium

lining of inside of the nose with 6 million olfactory receptor neurons

olfactory receptor neurons use this type of receptor

metabotropic

Where the synapse for smell occurs

glomeruli

smell has labeled line system but _______ ___ ________ ________ _________ ________ _______

odorant can activate multiple different olfactory neurons

Olfactory pathway in and through brain

olfactory bulb, amygdala and primary olfactory cortex, thalamus and hypothalamus, orbitofrontal cortex

Flavor is a combination of

taste and olfaction

Ability to perceive large number of different odors correlates to what?

generating complex array of flavors that we associate with tastes

some taste cells have what receptors?

functional olfactory receptors