Section A: Multiple Choice Questions Sensory Physiology MCQs 1. Which sensory modality is transduced by free nerve endings? a) Audition b) Pain c) Proprioceptio
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 type of nerve fibres? a) Aδ fibres b) C fibres c) Aβ fibres d) Aα fibres Answer: b) C fibres Explanation: Crude touch is transmitted via unmyelinated C fibers. 18. Vibration sensation is detected by which type of mechanoreceptor? a) Free nerve endings b) Ruffini endings c) Pacinian corpuscles d) Meissner’s corpuscles Answer: c) Pacinian corpuscles Explanation: Pacinian corpuscles are specialized for detecting high-frequency vibrations. 19. Which pathway transmits proprioception and kinesthesia from the lower limbs? a) Dorsal column pathway b) Spinothalamic pathway c) Spinocerebellar pathway d) Trigeminal pathway Answer: a) Dorsal column pathway Explanation: The dorsal column-medial lemniscus pathway transmits proprioception and fine touch. 20. Joint position sense is mediated by receptors located in: a) Ligaments b) Muscles c) Tendons d) All of the above Answer: d) All of the above Explanation: Proprioception is mediated by receptors in ligaments, muscle spindles, and Golgi tendon organs. 21. Pain and temperature sensations from the face are transmitted through which pathway? a) Medial lemniscal pathway b) Trigeminal pathway c) Spinothalamic pathway d) Reticular pathway Answer: b) Trigeminal pathway Explanation: The trigeminal nerve (CN V) transmits these sensations from the face. 22. Which neurotransmitter is involved in pain modulation by natural opioids? a) Serotonin b) Dopamine c) Endorphins d) Glutamate Answer: c) Endorphins Explanation: Endorphins modulate pain by binding to opioid receptors. 23. Selective NSAIDs exert their effects primarily by inhibiting which enzyme? a) Cyclooxygenase-1 (COX-1) b) Cyclooxygenase-2 (COX-2) c) Lipoxygenase d) Phospholipase A2 Answer: b) Cyclooxygenase-2 (COX-2) Explanation: Selective NSAIDs primarily inhibit COX-2 to reduce inflammation. 24. Which type of opioid receptor is primarily responsible for mediating analgesia? a) Mu (μ) b) Delta (δ) c) Kappa (κ) d) Nociceptin (ORL-1) Answer: a) Mu (μ) Explanation: Mu receptors are the primary mediators of opioid-induced analgesia. 25. Aspirin can interfere with the production of which prostaglandins important for renal blood flow? a) PGE₂ b) PGI₂ c) PGD₂ d) PGF₂ Answer: b) PGI₂ Explanation: PGI₂ (prostacyclin) maintains renal blood flow; its inhibition can cause renal issues. 26. There is a higher incidence of MI and stroke with the following except? a) Celecoxib b) Thromboxane c) Prostacyclin d) Ibuprofen Answer: c) Prostacyclin Explanation: Prostacyclin (PGI₂) is vasodilatory and anti-aggregatory, thus protective. 27. Which of the following is NOT a clinical test for somatosensory pathways? a) Pinprick test b) Two-point discrimination test c) Babinski reflex d) Tinel’s sign Answer: c) Babinski reflex Explanation: The Babinski reflex tests the upper motor neuron (corticospinal) tract. 28. Romberg test is used clinically to test for the integrity of? a) Posterior column pathway b) Anterolateral column pathway c) Neospinothalamic pathway d) Paleospinothalamic pathway Answer: a) Posterior column pathway Explanation: The Romberg test assesses proprioception (dorsal/posterior columns). 29. Damage to which pathway results in loss of discriminative touch? a) Dorsal column pathway b) S