The Human Brain: Facts, Information, and Research

Author: Disabled World (DW)
Updated/Revised Date: 2 Aug 2026

Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics

Synopsis

Explore the human brain, including its structure, hemispheres, neurons, and functions, along with facts, glossary terms, and the latest neurological research.

At a Glance

• 1 - There are no pain receptors in the brain, so the brain itself feels no pain.
• 2 - The brain uses roughly 20 percent of the body's oxygen and about 20 percent of its blood flow.
• 3 - Each cerebral hemisphere controls the opposite side of the body, so the right side manages the left and the reverse.
• 4 - The brain holds about 100 billion neurons and around 100,000 miles of blood vessels within roughly 3 pounds of tissue.

Topic Definition

Human Brain

The human brain is the central organ of the nervous system, housed within the skull, where it processes sensory information, directs movement, and governs thought, memory, emotion, and countless automatic functions such as breathing, heart rate, and body temperature. It shares the general structure of other mammalian brains but stands out for its highly developed cerebral cortex and its size relative to body weight, and it is built from roughly 100 billion neurons linked by trillions of connections called synapses. Organized into major regions - including the cerebrum, cerebellum, and brain stem, and grouped into the forebrain, midbrain, and hindbrain - the brain works with the spinal cord and peripheral nerves to monitor and regulate nearly all human activity. Made largely of water and fat and reliant on a constant supply of oxygen-rich blood, it remains one of the most complex and closely studied organs in the body.

Overview

The human brain is the center of the human nervous system. Enclosed in the cranium, it has the same general structure as the brains of other mammals, but is over three times as large as the brain of a typical mammal with an equivalent body size. An injury to the human brain is known as a Traumatic Brain Injury (TBI).

The human brain is one of the largest and most complex organs in the human body. It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses. Our brain gives us awareness of ourselves and of our environment, processing a constant stream of sensory data. It controls our muscle movements, the secretions of our glands, and even our breathing and internal temperature. The human brain has the same general structure as the brains of other mammals, but has a more developed cerebral cortex than any other. Large animals such as whales and elephants have larger brains in absolute terms, but when measured using the encephalization quotient, which compensates for body size, the human brain is almost twice as large as the brain of a bottle-nose dolphin, and three times as large as the brain of a chimpanzee.

The Brain has Two Cerebral Hemispheres

• Each takes care of one side of the body, but the controls are crossed: the right hemisphere takes care of the left side, and vice versa.
• If each hemisphere were unfolded, it would be the size of an extra-large pizza! For this reason, the brain must fold over on itself many times to fit into the skull.

The brain monitors and regulates the body's actions and reactions:

• It continuously receives sensory information, and rapidly analyzes this data and then responds, controlling bodily actions and functions.
• The brain stem controls breathing, heart rate, and other autonomic processes that are independent of conscious brain functions.
• The neocortex is the center of higher-order thinking, learning, and memory.
• The cerebellum is responsible for the body's balance, posture, and the coordination of movement.
• The human brain controls the central nervous system by way of the cranial nerves and spinal cord, the peripheral nervous system, and regulates virtually all human activity.
• The human brain is made up of over 100 billion nerve cells with each brain cell connected to around 10,000 other cells, which equals around 1000 trillion connections in your brain.

The brain can be divided into three basic units:

• the forebrain
• the midbrain
• the hindbrain

Studies of the Human Brain

For centuries, scientists, and philosophers have been fascinated by the brain, but until recently, they viewed the brain as nearly incomprehensible. Now, however, the brain is beginning to relinquish its secrets.

Scientists have learned more about the brain in the last 10 years than in all previous centuries because of the accelerating pace of research in neurological and behavioral science and the development of new research techniques. As a result, Congress named the 1990s the Decade of the Brain.

At the forefront of research on the brain and other elements of the nervous system is the National Institute of Neurological Disorders and Stroke (NINDS), which conducts and supports scientific studies in the United States and around the world.

Complete neuron cell diagram showing dendrites, neurotransmitter, and receptacle. Neurons (also known as neurones and nerve cells) are electrically excitable cells in the nervous system that process and transmit information. In vertebrate animals, neurons are the core components of the brain, spinal cord and peripheral nerves.

Brain Glossary

Glossary of words used to define various parts and actions relating to the human brain. There are more named components to the human brain than you may think, as usual medical naming most of the glossary of terms used to describe parts of the brain are from Latin.

Human Brain Facts and Information

• How much oxygen does the brain need to stay "conscious"? An adult's brain requires around 20% of the body's oxygen.
• How much blood is needed by the brain? Approximately 20% of the blood flowing from the heart is pumped to the brain. The brain requires constant blood flow to keep up with the heavy metabolic demands of the neurons.
• Does the brain work at the Speed of Light? No, far from it.
• Water - The brain is made up of about 75% water.
• Skin - Your skin weighs twice as much as your brain.
• Weight - The weight of the human brain is about 3 lbs.
• Neurons - Your brain consists of about 100 billion neurons.
• Gray and white - Your brain is 60% white matter and 40% gray matter.
• Blood vessels - There are 100,000 miles (160,934.4 kilometers) of blood vessels in the brain.
• No pain - There are no pain receptors in the brain, so the brain can feel no pain.
• Synapses - There are anywhere from 1,000 to 10,000 synapses for each neuron.
• The brain can stay alive for 4 to 6 minutes without oxygen. Thereafter, cells begin to die.
• Fat - The human brain is the fattest organ in the body and may consist of at least 60% fat.
• Gray matter - The brain's gray matter is made up of neurons, which gather and transmit signals.
• Cerebrum - The cerebrum is the largest part of the brain and makes up 85% of the brain's weight.
• The human brain is the center of the nervous system in animals. All vertebrates, and the majority of invertebrates, have a brain.
• The brain has the size and appearance of a small cauliflower. But thanks to its 100 billion nerve cells, we can think, plan, talk, imagine, and so much more.
• White matter - The white matter is made up of dendrites and axons, which create the network by which neurons send their signals.
• Einstein's brain was similar in size to other humans, except in the region that is responsible for math and spatial perception. In that region, his brain was 35% wider than average.
• The Largest brain. While an elephant's brain is physically larger than a human brain, the human brain is 2% of total body weight (compared to 0.15% of an elephant's brain), meaning humans have the largest brain to body size.

Frequently Asked Questions

How much energy does the human brain use

Although it makes up only about 2 percent of body weight, the brain uses a large share of the body's energy, drawing roughly a fifth of its oxygen and blood supply to power its billions of neurons.

What is the difference between gray matter and white matter

Gray matter is made up of neuron cell bodies that gather and process signals, while white matter consists of the axons and connections that carry those signals between brain regions.

Can the human brain repair itself

The brain has some capacity to adapt through neuroplasticity, forming new connections and rerouting functions after injury, though damaged neurons often do not fully regenerate.

What is a traumatic brain injury

A traumatic brain injury is damage to the brain caused by an external force such as a blow or jolt to the head, and it can range from a mild concussion to severe, lasting impairment.

Do people only use ten percent of their brain

No, the idea that people use only ten percent of the brain is a myth, since brain imaging shows that virtually all regions are active and serve important functions.

How does the brain communicate with the body

The brain sends and receives signals through the spinal cord and peripheral nerves, using electrical impulses and chemical messengers to control movement, sensation, and organ function.

What are the main parts of the human brain

The brain's main regions include the cerebrum for higher thinking, the cerebellum for balance and coordination, and the brain stem for automatic functions like breathing and heart rate.

Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.

Last updated: 2 Aug 2026