Common Misconceptions

Misconception: "Nerves and neurones are the same thing."

Reality: A neurone is a single nerve cell. A nerve is a bundle of many neurones (plus supporting cells and connective tissue) wrapped together, much like a cable containing many individual wires. When an exam question asks about "a neurone", it means the single cell.

Misconception: "All messages travel through the brain before a response is produced."

Reality: Reflex actions are coordinated in the spinal cord — the impulse never reaches the brain before the response occurs. The brain only becomes aware of the stimulus after the response has already happened.

Misconception: "Electrical impulses travel through the body like electricity through a wire."

Reality: Nerve impulses are electrochemical signals — they involve the movement of ions across the neurone membrane, not the flow of free electrons. They cannot jump between neurones; neurotransmitters must bridge each synapse chemically.

Misconception: "When ciliary muscles contract, the lens gets thinner."

Reality: It's the opposite. When ciliary muscles contract, the suspensory ligaments loosen, allowing the lens to become thicker and more curved. When ciliary muscles relax, the suspensory ligaments pull tight, making the lens thin and flat.