Anatomy II: Smell, Taste, Ear

Where are the Senses of the ear housed in the brain?

• Hearing = auditory cortex of the temporal lobe

• Equilibrium = in the cerebellum

Mechanoreceptors = receptors in the ear

Sections of the Ear

• Outer

• Middle Ear (ossicles)

• Inner ear (labyrinth and equilibrium)

Eustacian Tube

• Connects the middle ear to the throat

• Allows for equalizing pressure during yawning or swallowing (otherwise collapsed)

Middle ear

• 3 ossicles (malleus, incus, stapes)

Oval Window: Cochlea (sound enters)

Round Window: Pressre release in the cochlea

Vibration Effect on the Inner ear

• The stapes vibrates from the tympanic membrane and it pushes and pulls on the oval window

• This results in the movement of the perilymph in the oval window

Organ of Corti

• In the cochlea

Inner Stereocilia: Goes to the Brain

Outer Stereocilia: Controls amplification

Properties of Sound

Range of Human Hearing: 20-20,000 Hz

Intensity: Amplitude of Height

Decibels: Loudness

Hz: Frequency of the sound

Equilibrium

Static Equilibrium: In the vestibule

Dynamic equilibrium: In the semicircular canals

Static Equilibrium/vestibule

Maculae - Receptors in the vestibule

• Body Position

• Linear movement

• Sends information to the vestibular nerve

• Houses the otolith organs: utricle (horizontal movement) and the saccule (vertical movement)

Maculae

• hair cells are in the otolithic membrane

• Otolith - stones floating in the gel around hair cells

• Movement: Otolith bend the hair cells (gravity moves the rocks over the hair cells)

Dynamic Equilibrium

• WHOLE structure is the ampulla

• Crista Ampullaris - receptors in the semicircular canals

  • Cupula = gel cup that covers the hair cells in the semicircular canals

Cupula

• Cupula = stimulate the hair cells

• Movement of the endolymph pushes the cupula over and pulls the hairs

• An impulse is sent to the brain

Homeostatic Imbalance

Motion Sickness

• Sensory inputs are mismatched

• Visual input is different from equilibrium input

• Conflicting information

Hearing Loss

Conduction Deafness

• Blocked because of fluid in the ear

Sensorineural Deafness

• Damage to the auditory hair cells

Central Hearing Loss

• Damage in the brain but ears are fine

Tinnitus

Ringing, buzzing, clicking, in the absense of auditory stimulation

Chemical Taste

• Chemoreceptors

• 5 Types

• Sense of taste and smell complement each and are made of the same stimuli

Anatomy of the Tongue

• Taste buds are covered with papillae

Filliform = No taste buds

Taste Buds

• 20,000 - 10,000 on tongue

• Made of epithelial cells

• Taste receptors cells = on taste buds and are also gustatory cells

• Microvili are bathed in saliva = the receptor cels react to the dissolved molecules and generate impulses in sensory nerve fibers of the brain

Where are impulses carried in tongue

To the parietal lobes by three different craniel nerves

Taste Recepetors

Sweet

Sour

Bitter

Salty

Umami

What do we use our sense of smell for besides food

• Chemical detection without the danger of ingesting poisen

• Object identification

• Sexual signaling

Smell Sensory

• Olfactory receptors are in the roof in the nasal

• Neurons with long cilia

• Chemicals must be dissolved in the mucus for detection

Olfaction Transmitted

• Olfactory area of temporal lobe

• Transmitted via in the olfactory nerve

Anosmia

Absense of sense of smell

• Trauma

• Colds of allergies

• Blockage