Nervous System Learning Bits
Written by: Patrick McGurrin

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Flashcard facts and information about the nervous system

Biology Bits stories are a great way for you to learn about biology a little bit at a time. We’ve broken down information into pieces that are very tiny—bite-sized biology cards. Cutting out the cards will let you organize them however you want, or use them as flashcards while you read.

This set of bits will teach you about the system that senses the world around you and controls your body: your nervous system. To learn more about the science behind your nerves, visit A Nervous Journey.

Play the slide show from the beginning or pick a slide to begin with by clicking on a slide below.

Illustration of the human body with the general nervous system labeled.

The human body is made of trillions of cells. All of these cells have a special job. Neurons, or nerve cells, are the cells that allow the brain to communicate with the rest of the body. Neurons are in every part of your body, from the tip of your nose to the tips of your toes. Together, all the neurons in the body make up the nervous system. They allow the body to see, hear, taste, feel, move, and a lot more.

Illustration of neuron anatomy

Like other cells, neurons have parts that help them do certain jobs. Dendrites are at one end of the cell. They look like the branches of a tree. Dendrites receive messages from other neurons. The message then moves through the axon to the other end of the neuron. An axon looks like a long, thin tube that also branches at the end. The message moves to the tips of the axon and then into the space between neurons. From there the message can move to the next neuron.

Illustration of a young boy wiggling his right big toe.

Your brain and your big toe seem pretty far apart to a small cell. But if cells pass signals to each other, they can cover that distance in no time. Neurons talk to one another to help you to move your toes or scratch your nose. They talk by sending electrical signals called action potentials. These signals move fast, up to 150 meters per second. That's like running the length of a football field in less than a second. The nervous system needs to be fast. It helps you react to catch a ball or avoid something hot.

Illustration of impulses being sent from the skin to the brain and from the brain to the muscles.

The body sends two kinds of signals, sensory and motor. Sensory signals help you use your senses to explore the world around you. They tell you when you touch, see, feel, hear, or taste something. Neurons carry sensory signals from all around your body to the brain. Motor signals go the opposite way. They go from the brain to your muscles. They help you move or pick up objects.

Illustration of a human body, pointing out the brain and spinal cord.

The brain and spinal cord are large groups of neurons. Together they are called the central nervous system. The brain is located in the skull. The spinal cord runs through the bones of the spine. If you feel your skull or your spine, you can tell that those bones are hard. They help protect the brain and spinal cord from injury. The central nervous system needs to be kept safe because it is so important. The brain is the center of the nervous system. The spinal cord helps the brain communicate with the rest of the body.

Illustration of the peripheral nervous system.

The peripheral nervous system (PNS) is made of the nerve cells that are not in the brain or the spinal cord. One part of the PNS, the autonomic system, controls things that you aren’t able to. The autonomic system has two parts. The parasympathetic part helps your body to do things while relaxing, like digest food and slow your heartbeat. The sympathetic part is more active when you’re stressed. It might increase your heart rate and help you take in more oxygen.

Illustration showing what each part of the brain is responsible for.

The outer part of the brain is the cerebral cortex. Each section, or lobe, has a job. The frontal lobe shapes your personality. It also helps you move your body. The parietal lobe lets you know where your arms and legs are, even when you can't see them. The temporal lobe helps you hear things around you. The occipital lobe is at the back of the brain and it helps you to see.

Illustration of the inner (or middle) brain.

The inner brain is just like it sounds, in the middle of your brain. It helps your cerebral cortex to talk with other parts of the brain. The thalamus is also located here. It is the brain’s control center. It checks the messages going into or out of your brain. This helps make sure messages go to the right place. Another important part is also found here: the limbic system. This system lets you feel emotions and remember things.

Illustration showing brainstem anatomy.

The brainstem is a lower part of the brain. It is what connects the brain with the spinal cord. It is made of three parts. These are the midbrain, the medulla, and the pons. The brainstem controls many things that we don’t have to think about. This includes controlling things like our heart rate and blood pressure.

Illustration showing the two sides of the human brain.

The brain has two sides that are almost the same. In general, the right side of the brain controls the left side of the body. The left side of the brain controls the right side of the body. Imagine if the left side of your body didn’t know what the right side was doing. Walking, talking, and using your hands would be very hard. The tissue that connects the left and right sides of the brain is the corpus callosum. This lets the two sides of the brain talk to each other.

Illustration of different glial cell types

The brain is made up of more than just neurons. Glial cells are special cells in the brain. Their main job is to take care of the neurons. They provide nutrients to neurons to keep them healthy. They also cover them in a protective layer called myelin to help them send their signals as fast as the body requires. You can think of them like doctors or nurses for neurons. Below are different types of Glial cells.

An illustration of a brain lit up, as you would see on a screen during an fMRI.

The brain is very complex. How did we learn what each part of the brain does? Scientists can record the activity in the brain. They can look to see what part of the brain is active when a person performs an action (like talking and walking). This tells them the purpose of different parts of the brain. They are beginning to understand what many parts of the brain do, but have much more to explore.

Illustration of a talking human head

Hypothalamus – [high-puh-thal-uh-muhs]; Corpus callosum – [core puhs] [kuh-loh-suhm]; Cerebral cortex – [suh-ree-bruh-l] [core-tex]; Pituitary gland – [pi-too-i-ter-ee] [gland]; Hippocampus – [hip-a-kam-pus]; Thalamus – [thal-uh-muhs]; Astrocyte – [as-tro-sight]; Oligodendrocyte – [oli-go-den-dro-cyte]; Ependymal cell – [uh-pen-duh-mul] [cell]; Microglia – [mi-crog-lee-uh]; Dendrite – [den-dright]


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