The brain structure and function

Transcription

1 The brain structure and function This information is an extract from the booklet Understanding brain tumours. You may find the full booklet helpful. We can send you a copy free see page 5. Contents Introduction Main structures and functions of the brain Types of brain cells Primary and secondary brain tumours Introduction The brain and the spinal cord make up the central nervous system (CNS). This is the control centre that coordinates the body s functions. The brain is contained within the skull, which protects it. Between the brain and the skull there are three layers of membrane called the meninges (see diagram on page 2). These completely cover the brain and spinal cord and help to protect it. Between two of these layers is a space called the subarachnoid space. This space contains a fluid called cerebrospinal fluid (CSF). Main structures and functions of the brain The main parts of the brain are: the cerebrum (the forebrain) the cerebellum (the hindbrain) the brain stem. Questions about cancer? Ask Macmillan Page 1 of 5

2 Cerebrum (see diagram below) This is the largest area of the brain and controls all higher mental functions, such as thinking and memory. It s made up of two halves, or hemispheres. The right cerebral hemisphere controls the left side of the body, and the left cerebral hemisphere controls the right side of the body. Bone Subarachnoid space Brain Dura mater (outer layer) Arachnoid (middle layer) Pia mater (inner layer) Meninges Cerebrum Pituitary gland Bone Spinal cord The brain Each cerebral hemisphere is divided into four areas, known as lobes: Frontal lobe (see diagram opposite) controls thought, memory, planning, problem solving and behaviour. Parietal lobe is responsible for language, helping us form words and thoughts. It also deals with touch and how we recognise sensations, and helps us be aware of our body position. Temporal lobe helps us understand and process what Page 2 of 5 Questions about cancer? Ask Macmillan

3 we hear. It s also involved with how we learn and organise information.the temporal lobe is also responsible for emotions and emotional memory. Occipital lobe is where all visual information is processed, such as colour, shape and distance. This is the back part of the brain and is concerned with balance and coordination. These activities are carried out automatically (subconsciously) by this area of the brain and are not under a person s control. This controls the basic functions that are essential for maintaining life, including breathing, body temperature, heart rate and blood pressure. It also controls eye movements and swallowing. It s a very sensitive and important part of the brain, and it connects the cerebral hemispheres to the spinal cord. Thought, memory and behaviour Language and touch Visual processing Hearing, learning and emotions Balance and coordination Breathing, heart rate and temperature The lobes and functions of the brain PARTS OF THE BRAIN Frontal lobe Parietal lobe Temporal lobe Occipital lobe Questions about cancer? Ask Macmillan Page 3 of 5

4 Pituitary gland Just below the base of the brain is the pituitary gland. This is a small gland that makes lots of different hormones that control and regulate the other hormone-producing glands of the body. Types of brain cells Like every other organ in the body, the brain is made up of cells. There are about 40 billion nerve cells, called neurones, within the brain. Everyone is born with a similar amount. Unlike other cells, nerve cells can t replace themselves. In fact, as we get older there is a gradual decrease in their number. Nerve cells communicate with each other, and other parts of the body, by sending messages (nerve impulses) through a system of nerve pathways or networks. Nerve cells are held in place and supported by cells called glial cells. There are different types of glial cells, including astrocytes, oligodendrocytes and ependymal cells. Primary and secondary brain tumours Primary brain tumours Primary brain tumours are tumours that start in the brain and have not spread there from somewhere else in the body. Benign brain tumours remain in the part of the brain where they started, and don t spread into and destroy other areas of the brain. They don t spread to other parts of the body. If a benign brain tumour can be removed successfully it shouldn t cause any further problems. However, sometimes it s difficult to remove the tumour because of its position within the brain, or because the surrounding brain tissue could be damaged by surgery. Some benign tumours will regrow slowly and, if this happens, treatment with radiotherapy or further surgery may be needed. Page 4 of 5 Questions about cancer? Ask Macmillan

5 Malignant primary brain tumours are most likely to cause problems by spreading into the normal brain tissue around them, causing pressure and damage to the surrounding areas of the brain. These tumours rarely spread outside the brain to other parts of the body. Secondary brain tumours A secondary brain tumour is a cancer that has spread to the brain from another part of the body. Your doctor will be able to tell you if your brain tumour is a primary or secondary tumour. We have a fact sheet and information on our website about secondary brain tumours. More information and support Cancer is the toughest fight most of us will ever face. But you don t have to go through it alone. The Macmillan team is with you every step of the way, from the nurses and therapists helping you through treatment to the campaigners improving cancer care. We are Macmillan Cancer Support. To order a copy of Understanding brain tumours or one of the other booklets or fact sheets mentioned in this information, visit be.macmillan.org.uk or call We make every effort to ensure that the information we provide is accurate but it should not be relied upon to reflect the current state of medical research, which is constantly changing. If you are concerned about your health, you should consult your doctor. Macmillan cannot accept liability for any loss or damage resulting from any inaccuracy in this information or third party information such as information on websites to which we link. Macmillan Cancer Support Registered charity in England and Wales (261017), Scotland (SC039907) and the Isle of Man (604). Registered office 89 Albert Embankment, London, SE1 7UQ REVISED IN JUNE 2012 Planned review in 2014 Questions about cancer? Ask Macmillan Page 5 of 5