List the three auditory ossicles in the order they conduct sound from the tympanic membrane to the cochlea.
Malleus, Incus, and Stapes.
What is the primary function of the tympanic membrane in the hearing process?
It vibrates in response to sound waves and conducts those vibrations to the ossicles of the middle ear.
Which structure serves as the interface where the stapes transfers vibrations to the fluid of the inner ear?
Oval window.
What is the mechanical purpose of the round window in the cochlea?
It bulges outward to compensate for the inward movement of the oval window, allowing fluid waves to travel through the cochlea.
Identify the three fluid-filled chambers found within the coiled structure of the cochlea.
Scala vestibuli, scala media, and scala tympani.
How do the length and stiffness of the basilar fibers change from the base of the cochlea to its apex?
The fibers increase in length (approximately $12$-fold) and decrease in stiffness.
Why are the basilar fibers near the oval window (at the base of the cochlea) sensitive to high-frequency sounds?
They are short and stiff, which allows them to vibrate at higher frequencies.
Which specific organ within the cochlea contains the hair cells and generates nerve impulses?
Organ of Corti.
What is the role of the tectorial membrane in the Organ of Corti?
It is a gel-like coating in which the tips of the hair cells are embedded, causing them to bend when the basilar membrane vibrates.
How are auditory nerve impulses transmitted from the hair cells to the brain?
Through the cochlear nerve.
Which physiological principle states that the specificity of a sensation is determined by the point in the nervous system where the fiber terminates?
The Labeled Line Principle.
According to the Labeled Line Principle, why does pressing on your eye cause you to ‘see’ light?
Mechanical stress fires retinal receptors that lead to the brain’s visual center, which interprets all incoming impulses as light.
How is the ‘receptor potential’ related to the frequency of action potentials?
The further the receptor potential rises above the threshold, the higher the frequency of the resulting action potentials.
What is the primary difference between ‘tonic’ receptors and ‘phasic’ receptors?
Tonic receptors transmit signals continuously while a stimulus is present; phasic (rate) receptors react only when stimulus strength changes.
Provide an example of a rapidly adapting ‘phasic’ receptor mentioned in the text.
Pacinian corpuscle (or hair receptors).
Where are the chemoreceptors that monitor blood glucose, amino acids, and fatty acids located?
Hypothalamus.
Which vestibular structure detects rotational movement of the head?
Semicircular canals (or ducts).
Identify the enlargement at the end of a semicircular duct that contains the sensory organ for equilibrium.
Ampulla.
What is the ‘cupula’ in the context of the vestibular system?
A loose gelatinous tissue mass in the ampulla that bends in response to fluid flow, exciting hair cells.
Which vestibular organs are responsible for detecting linear head positioning and orientation?
The maculae of the utricle and saccule.
What is the orientation of the utricle compared to the saccule?
The utricle functions in the horizontal plane (upright position), while the saccule functions in the vertical plane (lying down).
What are the ‘statoconia’ found within the maculae of the inner ear?
Small calcium carbonate crystals embedded in the gelatinous layer that help detect changes in head position.
Bending the vestibular stereocilia toward the kinocilium results in which electrical change?
Depolarization (opening of ion channels).
Bending the vestibular stereocilia away from the kinocilium results in which electrical change?
Hyperpolarization (closing of ion channels).
