About Brain & Nervous System
The nervous system is the body's rapid communication network. The brain and spinal cord form the central nervous system, while nerves extend throughout the body. Billions of nerve cells exchange electrical and chemical signals that help you move, learn, feel, remember, and respond to the world.
Major Brain Regions
Different brain regions specialize in different jobs but work together.
Learn MoreNeurons
Neurons are cells specialized for rapid communication.
Learn MoreSpinal Cord
The spinal cord is a major information highway between the brain and body.
Learn MorePeripheral Nerves
Nerves connect the central nervous system to muscles, skin, organs, and sense receptors.
Learn MoreReflexes
Some responses are organized before the brain has time to make a conscious decision.
Learn MoreLearning and Memory
Memories depend on changing networks of connections between brain cells.
Learn MoreSleep
The brain stays active while you sleep.
Learn MoreProtecting the Brain
The skull, membranes, fluid, and blood-brain barrier help protect nervous tissue.
Learn MoreMajor Brain Regions
The cerebrum handles many higher functions including planning, language, voluntary movement, sensation, and memory. The cerebellum helps coordinate movement and balance. The brainstem controls essential automatic functions and connects the brain with the spinal cord.
Neurons
A neuron receives information through branching structures, processes signals in the cell body, and can send an electrical impulse along a long fiber called an axon. At synapses, chemical messengers help pass information to the next cell.
Spinal Cord
Bundles of nerve fibers carry sensory information toward the brain and movement commands away from it. The spinal cord is protected by the vertebral column and also helps organize fast reflex responses.
Peripheral Nerves
Some nerve fibers carry information toward the brain, while others carry instructions outward. A single nerve can contain many separate fibers bundled together.
Reflexes
A reflex pathway can route sensory information through the spinal cord and immediately activate muscles. The brain still receives information about what happened, but the first response can occur very quickly.
Learning and Memory
The brain does not store a memory in one simple location like a computer file. Different types of memory depend on different networks. Practice can strengthen useful pathways, and sleep helps many learning processes.
Sleep
Sleep cycles through different stages. During sleep the brain regulates hormones, processes information, supports memory, and performs maintenance functions. Teenagers generally need more sleep than adults because the brain and body are still developing.
Protecting the Brain
The brain floats in cerebrospinal fluid and is wrapped in protective membranes called meninges. Helmets and seat belts add external protection during activities where head injury is possible.