Follow a message along a nerve cell and across a synapse. See why a reflex is so fast, and what the forebrain, midbrain, hindbrain and spinal cord each do.
3 lessons, about 1 h 15 min3 simulations11 problems3 practice questionsPython in every lesson
Created by StemPy LabAnimals respond to changes around them through the nervous system. Receptors pick up a change, nerves carry the message as an electrical impulse, and effectors, such as muscles and glands, respond. A neuron has dendrites, a cell body, an axon and nerve endings. A chemical carries the message across the gap, the synapse, to the next neuron.
A reflex action is a quick, automatic response to a stimulus, done without thinking. The message follows a reflex arc: receptor, sensory neuron, relay neuron in the spinal cord, motor neuron, effector. The spinal cord answers at once, so the response is fast, and a message goes on to the brain as well.
The brain and the spinal cord make up the central nervous system. The forebrain thinks and controls voluntary actions; it also has the hunger centre. The midbrain and the hindbrain control involuntary actions: the medulla controls blood pressure, salivation and vomiting, and the cerebellum keeps balance. The skull, a fluid and the backbone protect them. Nerve impulses make muscles contract.
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