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Nature

Human Brain

What is human brain?

· James MacDonald

Key facts

organ central organ of the human nervous system[1]
weight about 3 pounds in the average adult[1]
cell types neurons and glial cells[1]
neuron count about 86 billion neurons[2]
main parts cerebrum, brainstem, cerebellum[2]

The human brain is the central organ of the human nervous system, controlling thought, memory, emotion, movement, and automatic functions like breathing and temperature regulation.

Context

The human brain is the central organ of the human nervous system and the body's control center for thought, memory, emotion, sensation, movement, and many automatic body functions such as breathing and temperature control [1]. It is part of the central nervous system with the spinal cord [1]. The brain is described as the most complex part of the human body [3]. It contains blood vessels and nerves, including neurons and glial cells [1]. It is made of nervous tissue and is an organ [4].

Documented claims

  • It controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger, and body regulation. [1]
  • It processes, integrates, and coordinates information from the sensory nervous system. [2]

Questions and answers

What are 5 facts about the human brain?

The human brain weighs about 3 pounds in an average adult [1]. It contains about 86 billion neurons [2]. It has three main parts: the cerebrum, brainstem, and cerebellum [2]. It is made up of neurons and glial cells [1]. It controls thought, memory, emotion, and many automatic functions [1].

What are the 4 main parts of the brain?

The brain has three main parts: the cerebrum, brainstem, and cerebellum [2]. Some sources also list the diencephalon as a fourth part, but the most common division is into three parts.

Sources

  1. Brain Basics: Know Your Brain — ninds.nih.gov (retrieved August 3, 2026)
  2. Physiology, Brain - StatPearls - NCBI Bookshelf - NIH — ncbi.nlm.nih.gov (retrieved August 3, 2026)
  3. The Human Brain 101 — mhanational.org (retrieved August 3, 2026)
  4. Brain: Parts, Function, How It Works & Conditions — my.clevelandclinic.org (retrieved August 3, 2026)

Sources last checked August 3, 2026. · More in Nature