Summary
The brain, spinal cord and nerves that sense, process and respond to information.
In depth
It senses internal and external conditions, integrates information and commands responses. The human brain has about 86 billion neurons and as many glial cells, with trillions of synapses. Communication is electrical along neurons and chemical between them.
Neural circuits process information in parallel and in hierarchies. Plasticity enables adaptation. The nervous system and endocrine system together coordinate the body.
Key idea: the nervous system works by electrical and chemical signalling.
The nervous system works by electrical impulses along neurons and chemical signals between them. Its three jobs, sensory input, integration and motor output, form a continuous loop. The human brain uses about 20 percent of resting energy despite being 2 percent of body weight, and has around 86 billion neurons and a similar number of glial cells, each neuron with thousands of connections. Nervous systems evolved from simple nerve nets in cnidarians to cephalised brains in bilaterians.
Neurology treats disorders of the system, and neuroscience brings together molecular, cellular, systems and cognitive levels. Techniques include electrophysiology, imaging and genetic tools. Santiago Ramon y Cajal's drawings in the 1890s established the neuron doctrine, that the nervous system is made of discrete cells.
Example: touching a hot pan triggers a fast spinal reflex first, and only afterwards does the brain register pain.
Frequently asked questions
What is Nervous System?
The brain, spinal cord and nerves that sense, process and respond to information.
Which area of biology covers Nervous System, and how advanced is it?
Nervous System is one of the 54 topics in Neuroscience. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Neuron, Cerebellum and Motor Learning, Cerebral Cortex.
Can you give an example of Nervous System?
Touching a hot pan triggers sensory input, processing and a rapid motor withdrawal.
What should I learn before Nervous System?
Nervous System is a Beginner topic, so no earlier topic is required. Other Beginner topics in Neuroscience that pair well with it include Neuron, Central and Peripheral Nervous Systems, Brain Regions.
What topics are related to Nervous System?
The closest topics to Nervous System are Neuron, Cerebellum and Motor Learning, Cerebral Cortex, Computational Neuroscience. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Nervous System?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Nervous System. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Nervous System different from Neuron?
Nervous System: The brain, spinal cord and nerves that sense, process and respond to information. Neuron: A nerve cell with dendrites, a cell body and an axon that transmits electrical signals. Read both side by side and note what each one explains.
How should I study Nervous System step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Neuron and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.