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Exploring the brain and nerves that control everything we do.
Did you know that a signal travels from your toe to your brain at over miles per hour? That is faster than a professional race car!
The nervous system is like your body's high-speed internet. It has two main parts. The first is the Central Nervous System (CNS), which includes your brain and your spinal cord. The brain is the 'boss'—it makes decisions and stores memories. The spinal cord is a thick bundle of nerves that runs down your back, protected by your spine. It acts like a main highway, carrying messages between the brain and the rest of your body. Without this connection, your brain wouldn't know what your hands or feet are doing!
Quick Check
What are the two main parts that make up the Central Nervous System?
Answer
The brain and the spinal cord.
The second part is the Peripheral Nervous System (PNS). This is made of millions of nerves that branch out from the spinal cord to every inch of your body. These nerves are made of special cells called neurons. Neurons send tiny electrical pulses to communicate. When you want to move your arm, your brain sends a signal down the spinal cord, through the nerves, and to your muscles in less than seconds! It is a two-way street: nerves also send 'input' signals back to the brain, like telling you a stove is hot.
1. You pick up a cold ice cube with your fingers. 2. Sensory neurons in your skin feel the cold temperature. 3. They send an electrical signal up your arm nerves to the spinal cord. 4. The signal reaches the brain, which thinks, 'Brrr, that is cold!'
Quick Check
What are the special cells called that carry electrical messages?
Answer
Neurons.
Your nervous system is also in charge of your five senses: sight, hearing, smell, taste, and touch. Each sense has special 'sensors' that collect data. For example, your eyes collect light and your ears collect sound vibrations. These sensors turn the data into electrical signals for the brain to translate. This process happens so fast that you see and hear things the exact moment they happen. Sometimes, the spinal cord takes over for the brain in an emergency—this is called a reflex, like when you jump back from a loud noise before you even realize what it was!
Imagine you accidentally step on a sharp LEGO brick. 1. Nerves in your foot detect pain immediately. 2. The signal travels to the spinal cord. 3. Instead of waiting for the brain to decide, the spinal cord sends a 'Move!' signal straight back to your leg muscles. 4. You lift your foot in just seconds—faster than you can think!
Which part of the nervous system is considered the 'Command Center' or 'Boss'?
What is a 'reflex'?
Nerves only send signals from the brain to the body, never the other way around.
Review Tomorrow
In 24 hours, try to explain to a friend the difference between the Central Nervous System and the Peripheral Nervous System.
Practice Activity
Try the 'Ruler Drop' test: Have a friend drop a ruler and see how fast you can catch it. This measures your reaction time—the speed of your nervous system!