Understanding the Brain - Fact Sheet

The brain controls and coordinates everything we do: movements, feelings, thoughts, breathing and bodily functions. The brain is made up of billions of nerve cells through which messages are transmitted by a combination of electrical and chemical activity.

The soft, jelly-like mass of the brain weighs around 1.3 kg and sits inside the skull, cushioned by cerebrospinal fluid. This fluid circulates around the brain and through a series of cavities called ventricles. The brain makes up only two percent of the body’s weight but uses 20% of the oxygen supply and blood flow. Brain cells begin to die if they do not receive oxygen after three to five minutes.

The brain is divided into a number of parts, which have specific functions and are designed to work together. The more these parts are coordinated and in tune with each other, the better the performance. The cells of the nervous system are quite fragile and need extensive protection from being crushed, being infected by disease organisms, and other harm.

LEFT AND RIGHT HEMISPHERES

The largest part of the brain is divided into two halves called the left hemisphere and the right hemisphere.
The left hemisphere is mainly involved with speech and language (talking, comprehension, reading and writing) and the right hemisphere is mainly involved with visual perception and interpretation of nonverbal information, such as drawing and spatial analysis. Each hemisphere is divided into four lobes.

FRONTAL LOBES

Frontal lobes are involved in problem-solving, planning, making judgments, abstract thinking and regulating how people act upon their emotions and impulses. Marked changes in a person’s personality and social skills can occur from damage to this area.

The motor strip at the back of the frontal lobes controls movement. In the left hemisphere the motor strip controls movement of the right side of the body while in the right hemisphere the motor strip controls movement of the left side of the body.

TEMPORAL LOBES

Temporal lobes are involved in receiving and processing auditory information e.g. music and speech, language comprehension, visual perception, organisation and categorisation of information. A major function of the temporal lobes is memory and learning.

The temporal lobes are also involved in personality, emotions and sexual behaviour.

PARIETAL LOBES

Parietal lobes are involved in monitoring sensation and body position, understanding time, recognising objects, reading and judging the position of objects in the environment.

OCCIPITAL LOBES

Occipital lobes receive, integrate and interpret visual information relating to colour, size, shape and distance.

THE CEREBELLUM

The cerebellum is located at the back and below the main hemispheres of the brain. It controls balance and the muscle coordination needed for large body movements. It lets a person know how fast, how hard, how far and in what direction his or her body parts are moving.
brain injury fact sheet

THE BRAIN STEM

The brain stem connects the brain to the spinal cord and regulates wakefulness, breathing, body temperature and heart activity. Cranial nerves are located in the brain stem, which regulate a number of functions such as swallowing, speech and eye movement.

CAUSES OF BRAIN INJURY

The brain can be injured as a result of an accident, a stroke, alcohol or drug abuse, tumours, poisoning, infection and disease, near drowning, haemorrhage, AIDS, and a number of other disorders such as Parkinson’s disease, Multiple Sclerosis, and Alzheimer’s disease.