The Brain Is Most of the Body's Energy Budget
The brain is the organ of thought. It is around two per cent of adult body weight and uses roughly a fifth of the body's energy.
The brain is the organ of thought, sensation and control. Its running costs are disproportionate: in an adult it makes up about two per cent of body weight and consumes roughly twenty per cent of the body's energy at rest, and in a small child the share is higher still. That expense is one reason biologists treat large brains as needing an evolutionary explanation.
- The organ of thought. *A human brain.*
- Intelligence. *He has brains.*
- The clever one. *She is the brains of the operation.*
- Brainstorm — to generate ideas, or a sudden idea. *A brainstorming session.*
- Brain drain — the loss of skilled people. *A brain drain to the cities.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | brain | The human brain. |
| Plural | brains | Brains and brawn. |
| Adjective | brainy | A brainy child. |
| Adjective | brainless | A brainless plan. |
| Old English | brægen | The brain. |
- The brain uses about a fifth of the body's energy.Physiology.
- She is the brains behind the design.Figurative.
- Rack your brains and try to remember.Idiom.
Brain facts worth knowing
- Energy — about twenty per cent of the body's resting energy use
- Neurons — commonly estimated at around eighty-six billion in an adult
- No pain receptors in the brain tissue itself, which is why awake brain surgery is possible
- The ten per cent myth is false — imaging shows activity throughout
- Development continues into the mid-twenties, particularly in the frontal lobes
Old English *brægen*, from a Proto-Germanic root, related to Greek *brekhmos*, the front of the head.
Do we only use ten per cent of our brains?
No. That claim has no basis. Imaging shows activity across the whole brain, though not all at once.
Why can brain surgery be done while awake?
Because brain tissue has no pain receptors. The scalp and skull are anaesthetised, and the patient can respond to tests during surgery.