You've Got a Lot of Nerve Trivia Quiz

Answer: No

The central nervous system (CNS) consists of the brain and the spinal cord. The brain is often used in nervous responses but when a reaction is needed very quickly then the impulse (action potential) often travels from the receptor to the spinal cord.

This is a reflex reaction and it takes less time to process the reaction by use of the spinal cord if the receptor is in the lower parts of the body. Some reflex reactions are processed by the brain itself.

Answer: Axon

The axon accounts for the greatest part of the length of a neurone. Along the axon are numerous protein channels and these allow potassium ions (K+) and sodium ions (Na+) to travel either from the inside of the neurone to the outside, or from the outside to the inside. It is through the movement of these ions that nerve impulses are propagated along the axon.

Answer: Myelin Sheath

The myelin sheath is a wonderful structure that consists of the membrane of a Schwann cell which encloses a layer of fat. This fat insulates the axon of a neurone. The reason that the presence of the myelin sheath causes a greater rate of propagation is that it allows an impulse to 'move' by a process known as saltatory conduction.

This requires less energy in the form of ATP (adenosine triphosphate) than other methods of impulse propagation.

Answer: Nodes of Ranvier

The nodes of Ranvier are the only places along an insulated axon that potassium ions (K+) and sodium ions (Na+) can diffuse in or out of the neurone. The diffusion of ions is essential if the impulse generated by a stimulus is going to reach the central nervous system.

The nodes of Ranvier are involved in increasing the rate of impulse propagation along an axon as the impulse can 'jump' from node to node rather than having to pass every protein channel, as would be the case in a non-insulated neurone.

Answer: Neurotransmitters

These neurotransmitters are essential if the impulse from one neurone is to be propagated along the axon of the next neurone. The neurotransmitters are secreted from the first neurone, stimulated to do so by the presence of calcium ions (Ca2+), and subsequently bind to protein receptors on the second neurone.

This results in the diffusion of sodium ions (Na+) and potassium ions (K+) in and out of the second neurone, thus generating an impulse. Examples of neurotransmitters are noradrenalin and acetylcholine.

Answer: Volts

When the ions diffuse into and out of the axon of the neurone the charges inside the axon can change from negative with respect to the outside to positive with respect to the outside. When sodium ions flood into an axon the charge inside changes from negative to positive with respect to the outside of the neurone.

When the sodium ions flood in the potential difference inside the axon changes from around -60 milliVolts (mV) to roughly +60 milliVolts (mV). The speed of this process always amazes me and it occurs constantly!

Answer: Tongue

You could work out the area of the body in question by use of the words 'mandibular' and 'lingual'. Mandibular is related to the word mandible which is the lower jaw and 'lingual' means relating to language. Thus the lingual nerve, one of the many branches of the mandibular nerve, detects stimuli from the tongue. If you bite your tongue or taste food, the stimulus will generate an impulse which will be propagated along the axons of the lingual nerve and the mandibular nerve before reaching the brain.

Answer: Light

Rods and cones are known as photoreceptors because they detect light entering the eye through the pupil and subsequently generate an impulse which travels along the optic nerve. The rod cells are responsible for scotopic vision (low-light vision) and accounts for our monochromatic vision in darkness.

The cone cells are responsible for photopic vision (high-light vision) and this type of vision allows us to see in colour.

Answer: Pressure

A Pacinian corpuscle is a type of mechanoreceptor, a receptor cell that detects changes in pressure by distortion. The corpuscle is mostly made of a gelatinous substance which, when pressure is applied, is flattened to reveal ion gates. Potassium ions (K+) and sodium ions (Na+) can subsequently diffuse in and out of a neurone, thus generating an impulse.

Answer: Motor Neurone Diseases

Motor neurone diseases affect, as the name suggests, the motor neurones which are responsible for every single responsive action including movement, breathing and talking. Apart from Lou Gehrig, one of the most famous sufferers of such a condition was Stephen Hawking.