5.2.1: Structure and function
Not started yet — this one needs some love.
The nervous system enables humans to react to their surroundings and coordinate their behaviour.
Information from receptors travels along neurones as electrical impulses to the central nervous system (CNS).
The CNS is the brain and spinal cord.
The CNS coordinates responses by effectors, such as muscles contracting or glands secreting hormones.
A reflex arc includes a receptor, sensory neurone, synapse, relay neurone, motor neurone and effector.
Reflex actions are automatic and rapid; they do not involve the conscious part of the brain.
Reaction-time data can be shown as numbers or graphs; for example, a longer ruler-drop distance means a slower reaction time.
Common exam mistakes
Do not say reflex actions are consciously chosen by the brain; the conscious part of the brain is not involved in the reflex action.
In a reflex arc, keep the order sensory neurone → relay neurone → motor neurone.
A synapse is a junction between neurones, not a type of neurone.
For reaction-time data, use the factor in the question, such as caffeine, practice or tiredness, and link it to faster or slower reactions.