Aims of this Episode:

  • Describe the structure of the nervous system,
  • Explain the function of the different parts of the nervous system,
  • Explain how Nerve Agents can affect the nervous system.

Nervous System

This is an organ system, just like the circulatory system or the digestive system. The nervous system is made up of the brain and nerves. It detects changes in your environment and coordinates the body’s response.

There are three different types of nerve in the body:

  • Sensory Neuron – the nerves that detect changes;
  • Relay Neuron – nerves that transfer messages around the body;
  • Motor Neuron – nerves that cause your body to do something.

You don’t have one continuous nerve moving through your body. Instead messages travel as small electrical impulses down the nerves and pass from one to another across a synapse. At the synapse the electrical message is turned into a chemical signal; when the chemicals arrive at the synapse of the next nerve they are converted back into electrical impulses to continue their journey. Click here to learn more about neurons.

Most major movements in your body are caused by signals sent from your brain to the muscles that cause the movement. However, in an emergency your brain is left out of the loop. For example, when you put your hand on something hot the sensory neurons in your skin cause a message saying that something is too hot, this message travels to your spinal column where the immediate response is sent back along a motor neuron causing you to pull your hand away. Without having to send a message to the brain your body can respond a lot faster and therefore less damage is caused to you. This is called a reflex response.

Nerve Agents

Nerve Agents are a type of chemical weapon that affect the nervous system. It is illegal to use chemical weapons in a war because of the damage they caused during World War One.

Most nerve agents attack the synapses between neurons. Many recreational drugs (like alcohol) cause changes in behaviour by affecting the same area of the nervous system. However, whilst recreational drugs only cause temporary changes, the damage caused by nerve agents is severe and can cause death.

Basically what happens is the nerve agent blocks the transmitting or receiving parts of the neuron. This means that you enter paralysis (you can’t move) because the messages can’t travel around your body. If the nerve agent continues to work eventually the messages from your brain telling your lungs to breath will stop and you will die.

Watch this video about how drugs affect the body and see if you can see similarities between them and nerve agents.

S@S 025: Nerve Agents (GCSE Biology)
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