Sensory Physiology and Neurophysiology MCQs

## Section A: Multiple Choice Questions ### Sensory Physiology MCQs **1. Which sensory modality is transduced by free nerve endings?** a) Audition b) Pain c) Proprioception d) All of the above **Answer:** b) Pain **Explanation:** Free nerve endings are primarily responsible for detecting pain (nociception) and temperature changes, not audition or proprioception, which involve specialized receptors. **2. Which of the following is most sensitive to light?** a) Cones maximally sensitive to light at 440 nm b) Cones maximally sensitive to light at 535 nm c) Cones maximally sensitive to light at 565 nm d) Rods **Answer:** d) Rods **Explanation:** Rods are highly sensitive to low light levels, enabling vision in dim conditions, whereas cones function best in bright light. **3. Taste buds are found in the:** a) Circumvallate papillae b) Fungiform papillae c) Foliate papillae d) All of the above **Answer:** d) All of the above **Explanation:** Taste buds are located in circumvallate, fungiform, and foliate papillae on the tongue. **4. All taste fibres first synapse in the:** a) Internal capsule b) Tractus solitarius c) Hypothalamus d) Inferior salivatory nuclei **Answer:** b) Tractus solitarius **Explanation:** Taste fibers from cranial nerves VII, IX, and X synapse in the nucleus of the tractus solitarius in the medulla. **5. The receptor for the stretch reflex is the:** a) Muscle spindle b) Golgi tendon organs c) Ruffini endings d) Pacinian corpuscle **Answer:** a) Muscle spindle **Explanation:** Muscle spindles detect muscle stretch and initiate the stretch reflex to maintain muscle tone and posture. **6. The fifth taste modality is:** a) Acidic b) Umami c) Sweetness d) None of the above **Answer:** b) Umami **Explanation:** Umami, associated with savory flavors (e.g., glutamate), is recognized as the fifth taste modality. **7. The light reflex is integrated in the:** a) Midbrain b) Frontal eye field c) Medulla d) Primary visual area **Answer:** a) Midbrain **Explanation:** The pupillary light reflex is integrated in the midbrain’s pretectal nucleus. **8. Saccades are:** a) Voluntary slow eye movements b) Involuntary slow eye movement c) Abrupt, involuntary slow eye movement d) Abrupt, voluntary rapid eye movements **Answer:** d) Abrupt, voluntary rapid eye movements **Explanation:** Saccades are rapid, voluntary eye movements that shift gaze to focus on different visual targets. **9. The secondary somatosensory cortex involves:** a) Brodmann’s areas 3a, 3b, 1, and 2 b) Broca’s areas 5 c) Brodmann’s areas 5, 7 d) Brodmann’s areas 4, 6 **Answer:** c) Brodmann’s areas 5, 7 **Explanation:** The secondary somatosensory cortex, located in the parietal lobe (Brodmann’s areas 5 and 7), processes complex tactile and proprioceptive information. **10. Inability to identify objects by touch is referred to as:** a) Astereognosis b) Stereognosis c) Autopagnosia d) Araphesthesia **Answer:** a) Astereognosis **Explanation:** Astereognosis is the inability to recognize objects by touch due to damage in somatosensory processing areas. **11. The dorsal column pathway is involved in the transmission of:** a) Pain b) Thermal sensations c) Vibratory senses d) Crude touch **Answer:** c) Vibratory senses **Explanation:** The dorsal column-medial lemniscus pathway transmits fine touch, vibration, and proprioception. **12. The spinothalamic pathway:** a) Is a fast pathway b) Is a slow pathway c) Is also called the medial lemniscus pathway d) Transmits pain and proprioception **Answer:** b) Is a slow pathway **Explanation:** The spinothalamic pathway transmits pain, temperature, and crude touch, using slower-conducting fibers. **13. Hydrogen ion (H+) is associated with which of the basic taste modalities?** a) Sweet b) Sour c) Salty d) Bitter **Answer:** b) Sour **Explanation:** Hydrogen ions (H+) are responsible for the sour taste. **14. The sensory hair cells of the cochlea organ of Corti are anchored on the:** a) Basilar membrane b) Vestibular membrane c) Tectorial membrane d) Tympanic membrane **Answer:** a) Basilar membrane **Explanation:** Hair cells in the organ of Corti are anchored to the basilar membrane, which vibrates in response to sound. **15. From the time a tactile stimulus is detected by a receptor in the foot to the time the resulting nerve impulses arrive in the postcentral gyrus, the impulses travel over how many neurons?** a) One b) Two c) Three d) Hundreds **Answer:** c) Three **Explanation:** The pathway involves a primary sensory neuron, a secondary neuron (synapsing in the medulla), and a tertiary neuron (thalamus to cortex). **16. Which type of receptor is primarily responsible for detecting light touch?** a) Free nerve endings b) Meissner’s corpuscles c) Pacinian corpuscles d) Merkel discs **Answer:** b) Meissner’s corpuscles **Explanation:** Meissner’s corpuscles are rapidly adapting mechanoreceptors specialized for light touch. **17. Crude touch sensation is mainly transmitted through which t