Free Nervous System and Special Senses MCQs with Answers

• A. Axon terminal
• B. Cell body
• C. Dendrite
• D. Myelin sheath

Explanation: Dendrites receive incoming signals and conduct them toward the cell body.

• A. Schwann cell
• B. Astrocyte
• C. Oligodendrocyte
• D. Microglial cell

Explanation: Oligodendrocytes form myelin around axons in the brain and spinal cord.

• A. Cerebral cortex
• B. Spinal cord
• C. Cerebellum
• D. Medulla oblongata

Explanation: The spinal cord integrates the rapid withdrawal reflex before conscious pain perception occurs in the cerebral cortex.

• A. Receptor, motor neuron, interneuron, sensory neuron, effector
• B. Receptor, sensory neuron, interneuron, motor neuron, effector
• C. Effector, sensory neuron, receptor, motor neuron, interneuron
• D. Sensory neuron, receptor, motor neuron, interneuron, effector

Explanation: A stimulus is detected by a receptor, carried by a sensory neuron to the spinal cord, processed through an interneuron, and sent by a…

• A. The central system contains nerves, while the peripheral system contains the brain
• B. The central system contains the brain and spinal cord, while the peripheral system contains nerves
• C. The central system controls muscles, while the peripheral system controls only glands
• D. The central system carries sensation, while the peripheral system carries only motor signals

Explanation: The central nervous system consists of the brain and spinal cord. The peripheral nervous system includes cranial nerves, spinal nerves…

• A. Skin receptors detect tissue injury
• B. A sensory neuron carries impulses inward
• C. The cerebral cortex recognizes the pain
• D. A spinal reflex causes muscle contraction

Explanation: Sensory reception begins when receptors detect a stimulus, whereas conscious perception occurs when the cerebral cortex interprets it.

• A. Cornea
• B. Lens
• C. Retina
• D. Iris

Explanation: The retina contains rods and cones that convert light into nerve signals.

• A. Cochlear receptors
• B. Vestibular receptors
• C. Olfactory receptors
• D. Gustatory receptors

Explanation: Vestibular receptors in the inner ear detect head movement and help maintain balance.

• A. Acetylcholine
• B. Norepinephrine
• C. Dopamine
• D. Serotonin

Explanation: Most postganglionic parasympathetic neurons release acetylcholine at the effector organ.

• A. The membrane becomes temporarily more negative inside
• B. Sodium ions rapidly enter through open channels
• C. Potassium ions stop moving across the membrane
• D. The myelin sheath releases neurotransmitter molecules

Explanation: An action potential begins with rapid opening of voltage-gated sodium channels, allowing sodium to enter the neuron and depolarize its…

• A. Astrocyte
• B. Microglial cell
• C. Schwann cell
• D. Ependymal cell

Explanation: Schwann cells form the myelin sheath around peripheral nerve fibres. Oligodendrocytes perform the comparable function in the central…

• A. Faster release of acetylcholine at the synapse
• B. Failure of action potential conduction along the nerve
• C. Increased sensitivity of the sensory receptor
• D. Continuous contraction of the supplied muscle

Explanation: Sodium channel blockade prevents the depolarization needed to start and conduct an action potential, so pain signals cannot travel…

• A. To produce neurotransmitters at the cell body
• B. To increase the speed of impulse conduction
• C. To detect chemicals at a sensory receptor
• D. To connect the spinal cord with skeletal muscle

Explanation: Myelin electrically insulates the axon and allows the impulse to jump between nodes of Ranvier, greatly increasing conduction speed.

• A. Entry of calcium ions into the terminal
• B. Exit of chloride ions from the terminal
• C. Breakdown of acetylcholine in the synaptic cleft
• D. Reuptake of neurotransmitter by the postsynaptic cell

Explanation: Arrival of an action potential opens voltage-gated calcium channels in the presynaptic terminal.

• A. The ciliary muscles relax and the lens flattens
• B. The ciliary muscles contract and the lens becomes more rounded
• C. The pupil closes and the retina moves forward
• D. The optic nerve shortens and the cornea becomes opaque

Explanation: For near vision, ciliary muscle contraction reduces tension on the suspensory ligaments, allowing the lens to become more rounded and…

• A. Semicircular canals
• B. Organ of Corti
• C. Auditory tube
• D. Olfactory bulb

Explanation: The organ of Corti lies within the cochlea and contains hair cells that convert sound vibrations into nerve impulses.

• A. Chorda tympani branch of the facial nerve
• B. Tibial branch of the sciatic nerve
• C. Phrenic nerve from the cervical plexus
• D. Greater occipital nerve from the spinal cord

Explanation: Taste from the anterior two-thirds of the tongue travels through the chorda tympani branch of cranial nerve VII, the facial nerve.

• A. Optic nerve
• B. Trigeminal nerve
• C. Olfactory nerve
• D. Vestibulocochlear nerve

Explanation: The olfactory nerve, cranial nerve I, carries impulses from olfactory receptors in the nasal mucosa.

• A. Dopamine
• B. Norepinephrine
• C. Acetylcholine
• D. Serotonin

Explanation: Both sympathetic and parasympathetic preganglionic neurons release acetylcholine onto nicotinic receptors in autonomic ganglia.

• A. Astrocyte
• B. Microglial cell
• C. Ependymal cell
• D. Oligodendrocyte

Explanation: Microglial cells act as the phagocytic immune cells of the central nervous system.