Special Senses General Notes for Phys Exam 2

Taste and smell give us the ability to:

Distinguish undesirable foods (lethal foods) from nutritious foods and recognize the proximity of others.

Taste and smell are tied to what?

Primitive emotional and behavioral functions of the nervous system (pheromones).

What are the 5 primary taste sensations?

Sour (acids), Salty (ionized salts), Sweet (organic compounds), Bitter (nitrogen alkaloids), Umami (glutamate, savory).

Where are the 3 types of taste buds located?

Circumvallate, posterior; Foliate, lateral edges; Fungiform, center (flat).

Where are the extraglossal taste buds located?

Tonsils, palate, epiglottis, esophagus.

Is a taste receptor a neuron?

No, it is not a true neuron. It does not contain an axon.

Where can each of the 5 primitive tastes be tasted on the tongue?

Sweet, tip of tongue; Salty, anterolateral; Sour, posterolateral; Bitter, posterior and palate; Umami, central.

How is taste transmitted to the brain?

Activation of taste buds excite the taste fibers, then transmitted to the thalamus, ending in the gustatory cortex.

The anterior 2/3 of the tongue is innervated by what nerve?

Facial nerve.

What is the concept of a labelled line?

In sensory biology, the labeled line theory for taste posits that each basic taste quality is represented by highly specific, dedicated neural pathways.

What is population coding in terms of taste?

The mechanism by which the brain identifies specific flavors and their intensities using the combined, simultaneous activity of a large group of broadly tuned neurons.

Do taste sensations adapt slowly or rapidly?

Rapidly.

Where is the olfactory membrane located?

Superior part of each nostril.

What do olfactory cells contain?

Cilia.

What is the binding of odorant to protein induced?

A G-protein induced formation of cAMP, which opens ion channels.

Do olfactory receptors adapt slowly or rapidly?

Very slowly.

What are the 7 primary sensations of smell?

Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.

What is the function of the tympanic membrane?

Transmit vibrations in the air to the cochlea.

How is the tympanic membrane able to amplify the signal?

It is 17 times larger than the oval window.

What are the 3 ossicles connected to the tympanic membrane?

Malleus, Incus, Stapes.

What are the two muscles attached to the ossicles?

Stapedius, Tensor tympani.

How long does a loud noise initiate reflex contraction?

40-80 milliseconds.

How is the cochlea protected from your own voice?

Muscles attached to the ossicles move instantly to attenuate vibration.

What are the 3 compartments of the cochlea?

Scala tympani, Scala media, Scala vestibuli.

What does sound waves cause back and forth movement of?

The tympanic membrane.

What is the function of the Organ of Corti?

Receptor organ that generates nerve impulses.

Where is the Organ of Corti located?

On the surface of the basilar membrane.

What are stereocilia?

The hair cells containing mechanoreceptors.

Where is the tectorial membrane located?

Above the stereocilia of the hair cells.

What happens when the stereocilia is bent in one direction?

Depolarization.

What occurs if stereocilia is bent in the opposite direction?

Hyperpolarization.

What is hyperpolarization responsible for?

Neural transduction of hearing.

The inner hair cells are responsible for what?

Hearing.

What is the function of the motor proteins within the outer hair cells?

They amplify the signal and shrink when the sound is too loud.

What do hair cells and the endolymph have in common?

Hair cells are modified neurons and are surrounded by endolymph high in potassium (K+).

What is the place principle?

Determines the frequency of a sound.

How is amplitude determined?

By how much the basilar membrane vibrates.

What is a decibel?

Unit of sound.

What are the 6 steps of the central auditory pathway?

Cochlear nerve, Medulla, Pons, Corpora quadrigemina, Thalamus, Auditory cortex.

What are the two categories of deafness?

Nerve deafness and conduction deafness.

What is the vestibular apparatus?

A system of bony tubes and chambers housed in the temporal bone.

What are the 2 components of the vestibular apparatus?

Semicircular canals and vestibule (utricle, saccule).