Special Senses General Notes for Phys Exam 2

Taste and smell give us the ability to:

    Distinguish undesirable foods (lethal foods) from nutritious foods

    Recognize the proximity of others

Taste and smell is tied to what?

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

What are the 13 possible chemical receptors in taste buds (no memorization)?

    1. 2 for sodium (Na)

    2. 2 for potassium (K+)

    3. Chloride

    4. Adenosine

    5. inosine

    6. 2 sweet

    7. 2 bitter

    8. gluamate

    9. hydrogen ion

What are the 5 primary taste sensations?

    Sour (acids)

    Salty (ionized salts)

    Sweet (organic compounds)

    Bitter (nitrogen alkaloids)

    Umami (glutamate, savory)

What are the 3 types of taste buds and where are they 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 (sensory relay station)

    Finally ends in the gustatory cortex

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

    Facial nerve

The posterior 1/3 of tongue is innervated by what nerve?

    Glossopharyngeal nerve

The posterior aspects of the mouth is innervated by what nerve?

    Vagus nerve

What is the concept of a labelled line?

    In sensory biology, the labeled line theory for taste posits that each basic taste quality (sweet, salty, sour, bitter, and umami) is represented by highly specific, dedicated neural pathways. From the sensory receptor on the tongue to the brain, each "line" of communication is exclusively labeled for one specific taste.

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 (or ensemble) of broadly tuned neurons, rather than relying on a single, isolated cell

Do taste sensations adapt slowly or rapidly?

    RAPIDLY

Where is the olfactory membrane located?

    Superior part of each nostril

The olfactory membrane contains what cells?

    Olfactory cells

Olfactory cells contain what?

    Cilia

The cilia within the olfactory cells contain what that aids in smell?

    Odorant binding proteins

The binding of oderant to protein induces what?

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

A substance must be volatile in order to be sniffed into the nostrils, what are these two characteristics?

    The substance must be slightly H2O soluble

    the substance must be slightly “lipid” soluble

Do olfactory receptors adapt slowly or rapidly?

    VERY SLOWLY

Does the olfactory sensation adapt slowly or rapidly?

    RAPIDLY

What are 7 primary sensations of smell?

    1. Camphoraceous (sharp, fresh, medicinal)

    2. Musky (warm, heavy)

    3. Floral (flower)

    4. Pepperminty

    5. Ethereal (light, chemical-like)

    6. Pungent (strong, sharp smell, may be irritating)

    7. Putrid (foul, rotting order, decaying organic matter)

What is the function of the tympanic membrane?

    Transmit vibrations in the air to the cochlea (that is filled with fluid)

How is the tympanic membrane able to amplify the signal?

    It is able to amplify the signal because 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 that are attached to the ossicles?

    Stapedius

    Tensor tympani

A loud noise initiates reflex contraction after how long?

    40-80 MILLISECONDS

How is the cochlea protected from your own voice?

    When you start to talk, the muscles attached to the ossicles move instantly, which initiates the reflex contraction. This causes the vibration to attenuate. Attenuating the vibration (dampening it), ultimately protects the cochlea.

What are the 3 compartments of the cochlea?

    Scala tympani

    Scala media

    Scala vestibuli

Sound waves cause back and forth movement of the tympanic membrane, which moves the stables back and forth, against what?

    Against the oval window

The sound waves cause displacement of fluid in the cochlea and creates vibrations, in what area of the ear?

    Basilar membrane

What is the function of the Organ of Corti?

    Receptor organ that generates nerve impulses (organ of hearing)

Where is the Organ of Corti located?

    On the surface of the basilar membrane, it also contains the rows of cells with sterocilia

What are stereocilia?

    The hair cells, which contain mechanoreceptors (detect vibration)

Where is the tectorial membrane located?

    ABOVE the sterocilia of the hair cells

Movement of the basilar membrane cause what to happen?

    the sterocilia of the hair cell receptors to bend

If stereocilia is bent in one direction, what occurs?

    Depolarization

If sterocilia is bent in the opposite direction, what occurs?

    Hyperpolarization

Hyperpolarization is responsible for what?

    Neural transduction of hearing

What hair cell is the “most in charge”?

    Kinocilium

The inner hair cells are responsible for what?

    Hearing

The inner hair cells connect to how many sensory afferents?

    95%

The outer hair cells connect to how many sensory afferents?

    5%

The outer hair cells contain what proteins?

    Motor proteins

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

    They either stretch to amplify the signal and will shrink when the sound is too loud

CLINICAL APP, MOTOR PROTEINS:

    Certain anti-biotics can attack the motor proteins, especially in young children

Hair cells are modified what?

    Neurons

Hair cells are surrounded by what fluid?

    Endolymph

The endolymph surrounding the hair cells is high in what ion?

    K+, higher ECF K+ than inside the cell (THIS IS THE ONLY PLACE IN THE BODY THAT THIS OCCURS)

What is the place principle?

    Determines frequency of a sound

A different frequencies of sound will cause what?

    Basilar membrane to vibrate at different positions

Position along the basilar membrane where hair cells are being stimulated determines what?

    Pitch

How is amplitude determined?

    How much the basilar membrane vibrates

A decibel is:

    Unit of sound

0.1 bel is a:

    decibel

1 decibel is an increase in sound energy of:

    1.26 times

What are the 6 steps of the central auditory pathway?

    1. Cochlear nerve (vestobliocochlear)

    2. Medulla

    3. Pons

    4. Corpora quadrigemina (inferior colliculus)

    5. Thalamus (NOT OLFACTORY)

    6. Auditory cortex (temporal)

The superior olivary nucleus (pons) divide into what two parts?

    Lateral

    Medial nuclei

The lateral nuclei detects direction by:

    Difference in sound intensity between both ears

The medial nuclei detects direction by:

    Time lag between the 2 ears

What are the two categories of deafness?

    Nerve deafness

    Conduction deafness

Nerve deafness is:

    Cochlea of nerve CN VIII

Conduction deafness is:

    Impairment of your tympanic membrane or ossicles

The brainstem and inner ear contain centers for what?

    Stereotypic movement and equilibrium

    Detecting and maintaining balance

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 (ducts)

    Vestibule (utricle, sacule)

The utricle and the saccule are sensory organs for detecting the orientation of the head with respect to gravity, which is called:

    Macula