The brain and spinal cord

The brain and spinal cord (called the central nervous system) control many of the body’s functions. Different areas of this system do different things. Some areas control movement or how we think, feel, learn or behave. Other areas control things like breathing and heart rate.

The brain and spinal cord are made up of billions of nerve cells. These form a network to send messages between the brain and other parts of the body. Nerve cells are held in place and supported by other types of cells, including astrocytes, oligodendrocytes and ependymal cells.

Layers of tissue called the meninges surround and protect the brain and spinal cord. A fluid called cerebrospinal fluid (CSF) circulates between some of the layers. This helps cushion the brain. It also circulates nutrients to the brain and removes waste products.

The central nervous system

Together, the brain and the spinal cord are called the central nervous system (CNS). Our brain controls how we think, feel, learn and move. It also controls other important things in the body without us being aware of it, such as breathing and heart rate. The bones of the skull protect the brain.

The spinal cord is a long bundle of nerves down the middle of the backbone (spine). It starts at the base of the brain and goes down to the small of the back. Messages between the brain and other parts of the body travel through the spinal cord. The bones of the backbone (vertebrae) protect the spinal cord.

The brain and spinal cord are also covered and protected by three layers of tissue (membranes) called the meninges. The area between two of these layers (the subarachnoid space) contains a liquid called cerebrospinal fluid (CSF). This makes a protective cushion for the brain. The liquid also circulates nutrients to the brain and removes waste products.


Nerve cells (neurons)

The brain and spinal cord are made up of billions of nerve cells called neurons. These cells communicate with each other by sending chemical messages (neurotransmitters) to each other. They form a network to send messages between the brain and other parts of the body.

Nerve cells, unlike other cells in the body, can’t replace themselves. They gradually decrease in number as we get older. Nerve cells are held in place and supported by glial cells. There are different types of glial cells, including astrocytes, oligodendrocytes and ependymal cells.


Main areas of the brain

The main parts of the brain are the cerebrum, cerebellum, brain stem and pituitary gland.


Cerebrum

This is the largest part of the brain and is made up of two halves (hemispheres). It controls thinking, memory, behaviour and personality. The right half of the cerebrum controls the left side of the body. The left half of the cerebrum controls the right side of the body.

Side view of the brain
Side view of the brain

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Each half of the cerebrum is divided into four areas (lobes):

  • The frontal lobe is responsible for thinking, planning, problem solving and behaviour. Certain areas of the frontal lobe control movement in the arms and legs and how we produce speech.
  • The parietal lobe helps us form our words. It also helps us interpret touch and other sensations, and makes us aware of our body position.
  • The temporal lobe manages memory, feelings and our understanding. It processes what we hear and smell. It also helps us with organising information, learning and speech.
  • The occipital lobe processes information about what we see, for example colour, shape and distance.

Areas of the cerebrum
Areas of the cerebrum

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Cerebellum

This is the area below the cerebrum, at the back of the brain. It controls balance and co-ordination.

Brain stem

The brain stem is at the bottom of the brain, connected to the spinal cord. It controls important body functions that keep us alive, such as breathing, heart rate, blood pressure and body temperature. It also controls eye movements and swallowing.

Cranial nerves

These are nerves that go from the brain and brain stem to the eyes, nose, ears, tongue, face and shoulders. They carry messages about sensations, such as taste, smell, vision and hearing from these areas. They also carry messages to muscles that control eye and face movements, speech and swallowing.

Pituitary gland

The pituitary gland is behind the nose and just below the base of the brain. It makes hormones that control other hormone-producing glands in the body, such as the adrenal and thyroid glands. Hormones are chemical messengers that help control how organs and tissues in the body work.

Pineal gland

The pineal gland is near the centre of the brain, between the two halves of the cerebrum. It makes a hormone called melatonin that helps control sleep patterns.

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