Nervous System

Nerves

What are nerves? They're the thin threads of nerve cells, called neurons that run throughout your body. Bundled together, they carry messages back and forth just the way that telephone wires do. Sensory nerves send messages to the brain and generally connect to the brain through the spinal cord inside your backbone. Motor nerves carry messages back from the brain to all the muscles and glands in your body.

Nervous System

What is the nervous system? Made up of your brain, your spinal cord, and an enormous network of nerves that thread throughout your body, it's the control center for your entire body. Your brain uses information it receives from your nerves to coordinate all of your actions and reactions. Without it, you couldn't exist!

Brain

You carry around a three-pound mass of wrinkly material in your head that controls every single thing you will ever do. From enabling you to think, learn, create, and feel emotions to controlling every blink, breath, and heartbeat—this fantastic control center is your brain. It is a structure so amazing that a famous scientist once called it "the most complex thing we have yet discovered in our universe."

Amygdala

Your brain has a little bunch of cells on each side called the amygdala (say: uh-MIG-duh-luh). The word amygdala is Latin for almond, and that's what this area looks like. Scientists believe that the amygdala is responsible for emotion. It's normal to feel all different kinds of emotions, good and bad. Sometimes you might feel a little sad, and other times you might feel scared, or silly, or glad.

Spinal Cord

The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The human spinal cord is protected by the bony spinal column shown to the left. The spinal column is made up of bones called vertebrae.

Thalamus

The thalamus receives sensory information from other areas of the nervous system and sends this information to the cerebral cortex. The thalamus is also important for processing information related to movement.

Brain Stem

Another brain part that's small but mighty is the brain stem. The brain stem sits beneath the cerebrum and in front of the cerebellum. It connects the rest of the brain to the spinal cord, which runs down your neck and back. The brain stem is in charge of all the functions your body needs to stay alive, like breathing air, digesting food, and circulating blood.

Dendrite

Dendrites (from Greek δένδρον déndron, "tree") are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.

Lobes of the Brain

FRONTAL LOBE: Located in front of the central sulcus. Concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving. PARIETAL LOBE: Located behind the central sulcus. Concerned with perception of stimuli such as touch, pressure, temperature and pain. TEMPORAL LOBE: Located below the lateral fissure. Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus). OCCIPITAL LOBE: Located at the back of the brain, behind the parietal lobe and temporal lobe. Concerned with many aspects of vision.

Motor Neuron

Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands.

Sensory Neuron

Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system.

Corpus Callosum

How many brains do you have - one or two? Actually, this is quite easy to answer...you have only one brain. However, the cerebral hemispheres are divided right down the middle into a right hemisphere and a left hemisphere. Each hemisphere appears to be specialized for some behaviors. The hemispheres communicate with each other through a thick band of 200-250 million nerve fibers called the corpus callosum.

Synapse

Information from one neuron flows to another neuron across a synapse. The synapse contains a small gap separating neurons.

Cerebellum

Next up is the cerebellum. The cerebellum is at the back of the brain, below the cerebrum. It's a lot smaller than the cerebrum at only 1/8 of its size. But it's a very important part of the brain. It controls balance, movement, and coordination (how your muscles work together).

Cerebrum

The biggest part of the brain is the cerebrum. The cerebrum makes up 85% of the brain's weight, and it's easy to see why. The cerebrum is the thinking part of the brain and it controls your voluntary muscles — the ones that move when you want them to. So you can't dance — or kick a soccer ball — without your cerebrum.

Hippocampus

The hippocampus is one part of the limbic system that is important for memory and learning.

Neuron

The human body is made up of trillions of cells. Cells of the nervous system, called nerve cells or neurons, are specialized to carry "messages" through an electrochemical process. The human brain has approximately 100 billion neurons.

Hypothalamus

The hypothalamus is like your brain's inner thermostat (that little box on the wall that controls the heat in your house). The hypothalamus knows what temperature your body should be (about 98.6°F or 37°C). If your body is too hot, the hypothalamus tells it to sweat. If you're too cold, the hypothalamus gets you shivering. Both shivering and sweating are attempts to get your body's temperature back where it needs to be.

Axon

axon, also called nerve fibre, portion of a nerve cell (neuron) that carries nerve impulses away from the cell body.