Chapter 7: Audition, the Body Senses, and the Chemical Senses

Question 1

1. Describe receptors involved in the perception of touch, temperature, pain, and itch.

Answer 1

Mechanoreceptors are activated by vibration.

Vibratory movement causes ion channels to open and change membrane potential to transduce the signal.

Thermal receptors are free nerve endings that are activated by a relative change in temperature.

Pain receptors are free nerve endings that are stimulated by intense pressure, heat, and chemical irritants.

Little is known about the receptors that are responsible for the sensation of itch.

Question 2

Outline the vestibular pathway.

Answer 2

From the hair cells, vestibular information is relayed to the
brain via the vestibular and cochlear nerves.

The vestibular nerve projects to the medulla, which sends information to cerebellum, spinal cord, pons, and to other regions of the medulla.

The cranial nerve relays information to the eye muscles to compensate for sudden head movements.

There also appear to be vestibular projections to the temporal cortex, but the precise pathways have not been determined.

Question 3

Describe the path of gustatory processing from nerves to subcortical and cortical structures.

Answer 3

Taste receptors in the tongue send taste information to the brain via cranial nerves.

Taste information first enters the
nucleus of the solitary tract in the medulla, then to the thalamus, then the primary gustatory cortex, and finally the secondary gustatory cortex.

Unlike most other sense modalities, taste is ipsilaterally represented in the brain.

The primary gustatory cortex contains a taste map.

Question 4

Contrast how loudness in high- and low frequency sounds is represented in the auditory
system using action potentials.

Answer 4

Loudness in high-frequency sounds is represented by an increased rate of action potentials from the auditory hair
cells.

Loudness in low frequency cells is represented by the number of axons arising from the low-frequency-detecting neurons at the apical end of the basilar membrane that are active at a given time.

Question 5

Identify the stimulus and describe the structure and function of the olfactory apparatus.

Answer 5

The stimuli for olfaction are chemical molecules that are
typically lipid soluble and organic.

Olfactory receptor cells are bipolar neurons whose cell bodies lie within the olfactory mucosa that lines the cribriform plate.

These neurons send information to the olfactory bulb and through the brain via olfactory tracts.

Some information proceeds to the

Question 6

Describe the process olfactory processing