D312 ANATOMY AND PHYSIOLOGY I - Set 5 - Part 3

Correct Answer: Cell body

Option c is correct because the cell body of the olfactory receptor cell contains the nucleus and is one of the three anatomical parts, alongside the dendrite that receives stimuli and the axon that transmits signals. Option a is incorrect because the dendrite is the part of the olfactory receptor cell that extends toward the nasal cavity surface to receive odorant molecules, not the part that houses the cell nucleus. Option b is incorrect because the axon is the part of the olfactory receptor cell that transmits neural impulses away from the cell body toward the brain, not the cellular component containing the nucleus. Option d is incorrect because cilia are projections on the olfactory receptor cell dendrites that perform olfactory transduction by contacting odorant molecules, and they are not one of the three main cell parts.

Correct Answer: Glomeruli

Option a is correct because glomeruli are the globular tangles within the olfactory bulbs where olfactory nerve fibers synapse with olfactory bulb neurons before signals continue through olfactory tracts to the brain. Option b is incorrect because ganglia are clusters of nerve cell bodies found in the peripheral nervous system and are not the specific globular synaptic structures within the olfactory bulbs for smell processing. Option c is incorrect because cristae are saddle-shaped ridges of mechanoreceptors within the ampullae of the semicircular canals that detect rotational head movement, unrelated to olfactory signal processing. Option d is incorrect because maculae are mechanoreceptor patches in the vestibule of the inner ear that detect gravity and linear acceleration, with no involvement in the processing of smell signals.

Correct Answer: Temporal lobe

Option d is correct because olfactory bulb neurons send processed smell information through the olfactory tracts to the temporal lobes of the brain for final olfactory processing. Option a is incorrect because the parietal lobe houses the primary gustatory cortex for taste processing rather than the final destination for olfactory signals traveling from the olfactory bulbs and tracts. Option b is incorrect because the occipital lobe is the primary processing center for visual information received from the optic nerves and does not serve as the destination for olfactory pathway signals. Option c is incorrect because the frontal lobe is located above the olfactory bulbs and is associated with motor control and executive function, but it is not the lobe receiving olfactory tract information.

Correct Answer: Roof of the nasal cavity

Option b is correct because the olfactory epithelium is a strip of mucous membrane located specifically on the roof of the nasal cavity where inhaled odorant molecules contact olfactory receptor cells. Option a is incorrect because the floor of the nasal cavity is not where the olfactory epithelium is located, as odorant detection requires the receptor strip to be positioned at the roof of the nasal passage. Option c is incorrect because while the lateral nasal wall contains structures like the nasal conchae for warming and filtering air, the olfactory epithelium is specifically positioned on the roof, not the sides. Option d is incorrect because the nasal septum divides the nasal cavity into two halves and is not the location of the olfactory epithelium, which sits specifically as a strip on the roof of the cavity.

Correct Answer: Odor threshold

Option c is correct because the odor threshold is defined as the lowest concentration of an odor compound that a human can perceive, and it varies between individuals and different odorant substances. Option a is incorrect because olfactory adaptation refers to the decreasing sensitivity of the olfactory epithelium to sustained odors over time, not the minimum concentration required for initial detection. Option b is incorrect because olfactory transduction is the process of converting chemical odorant molecules into neural impulses through local depolarization, not a measurement of detection concentration levels. Option d is incorrect because a receptor potential is the electrical change in a receptor cell caused by a stimulus and is a general neurophysiology term, not specifically the minimum detectable odor concentration.

Correct Answer: Taste reaches the parietal lobe; smell reaches the temporal lobe

Option a is correct because the gustatory pathway sends taste signals to the primary gustatory cortex in the parietal lobe, while the olfactory pathway sends smell signals to the temporal lobe for processing. Option b is incorrect because this reverses the correct cortical destinations, placing taste in the temporal lobe and smell in the parietal lobe, which is the opposite of where each sensory pathway terminates. Option c is incorrect because the occipital lobe is the primary visual processing center receiving signals from the optic nerves, and neither taste nor smell pathways terminate in the occipital lobe. Option d is incorrect because the frontal lobe handles motor functions and executive processing, and while it sits near olfactory structures, it is not the final processing destination for either taste or smell.

Correct Answer: One for smell, two for vision, eight for hearing and balance

Option d is correct because cranial nerve one is the olfactory nerve for smell, cranial nerve two is the optic nerve for vision, and cranial nerve eight is the vestibulocochlear nerve for hearing and balance. Option a is incorrect because cranial nerve one carries smell information, not visual impulses, and cranial nerve eight carries hearing and balance signals, while cranial nerve two is responsible for vision. Option b is incorrect because cranial nerve two is the optic nerve carrying visual impulses, not smell, and cranial nerve seven is the facial nerve for taste innervation, not for hearing or balance signals. Option c is incorrect because cranial nerve one is the olfactory nerve for smell, not hearing, and cranial nerve eight is the vestibulocochlear nerve for hearing and balance, not for smell detection.

Correct Answer: Maculae in the saccule and utricle

Option b is correct because maculae are mechanoreceptors located within the saccule and utricle of the vestibule that detect linear acceleration, head tilt, and body position changes relative to gravity. Option a is incorrect because cristae ampullaris in the semicircular canals detect rotational acceleration and angular head movements, which would cause dizziness from spinning rather than from tilting or standing. Option c is incorrect because hair cells in the organ of Corti are auditory receptor neurons within the cochlea that detect sound vibrations and are completely unrelated to detecting body position or movement. Option d is incorrect because photoreceptors in the retina are specialized cells that convert light into neural signals for vision and have no role in detecting body movement or gravitational position changes.

Correct Answer: Auricle, tympanic membrane, ossicles, oval window

Option c is correct because sound travels from the auricle collecting waves, to the tympanic membrane vibrating, through the ossicle chain transmitting vibrations, and finally to the oval window entering the inner ear. Option a is incorrect because this sequence places the tympanic membrane before the auricle, but sound waves must first be collected by the external auricle before reaching the eardrum inside the ear canal. Option b is incorrect because this sequence places the ossicles first, but they are located in the middle ear and receive vibrations only after the auricle collects sound and the tympanic membrane vibrates. Option d is incorrect because this sequence is completely reversed from the actual sound pathway, placing the oval window first and the auricle last, which is the opposite of sound wave progression.

Correct Answer: Glossopharyngeal nerve

Option d is correct because the glossopharyngeal nerve, cranial nerve nine, receives taste signals from vallate and foliate papillae and also provides general sensory innervation to the posterior third of the tongue. Option a is incorrect because the facial nerve, cranial nerve seven, innervates taste buds in the epiglottis and throat region and does not provide taste innervation to the vallate and foliate papillae. Option b is incorrect because the vagus nerve, cranial nerve ten, receives taste signals from gustatory receptors in the fungiform papillae and does not innervate the vallate and foliate papillae specifically. Option c is incorrect because the hypoglossal nerve, cranial nerve twelve, is a purely motor nerve controlling tongue muscle movements and carries no taste or general sensory information from the tongue.