CNS - The Central Nervous System
The central nervous system (CNS) controls most functions of the body and mind. It consists of two parts: the brain and the spinal cord. The brain is the center of our thoughts, the interpreter of our external environment, and the origin of control over body movement.
The human brain is the command center for the human nervous system. It receives input from the sensory organs and sends output to the muscles. The human brain has the same basic structure as other mammal brains, but is larger in relation to body size than any other brains.
Facts about the human brain
The human brain is the command center for the human nervous system. It receives input from the sensory organs and sends output to the muscles. The human brain has the same basic structure as other mammal brains, but is larger in relation to body size than any other brains.
Facts about the human brain
- The human brain is the largest brain of all vertebrates relative to body size
- It weighs about 3.3 lbs. (1.5 kilograms)
- The brain makes up about 2 percent of a human's body weight
- The cerebrum makes up 85 percent of the brain's weight
- It contains about 86 billion nerve cells (neurons) — the "gray matter"
- It contains billions of nerve fibers (axons and dendrites) — the "white matter"
- These neurons are connected by trillions of connections, or synapses
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