The Brain

the brain

The cerebrum is the largest part of your brain and makes up about 80% of its mass. It is divided into two halves, or cerebral hemispheres. Each half takes information from, and control muscles of the opposite side of the body. Your Cerebrum is also the centre of your intelligence, memory, speech and consciousness. The outer layer, called the cerebral cortex, is folded and grooved, and is made up of billions of nerve cells, known as grey matter. Inside this is the thick white matter of the cerebrum, made up of connecting fibres.
The cerebellum, which means 'little brain', is found behind the brain stem. It has two folded and grooved halves which are responsible for co-ordinated body movements, posture and balance. The outer layer, or cortex, contains nerve cell, or grey matter, and under this run their fibres, in the white matter.
The spinal cord is a column of nerve tissue about 45 cm in length and as thick as a finger. It is protected by a column of bones called vertebrae that form the spine. The spinal cord and the brain make up the central nervous system, and together they control most of your body's activities. The 31 pairs of spinal nerves, which fan out from the spinal cord, form the peripheral nervous system. These provide the main links between your brain and the rest of your body.
The medulla oblongata is the lowest part of the brain stem, next to the spinal cord. It is only 2.5 cm long. Nerve fibres cross over here, so that one side of your brain receives information from the opposite side of your body. The medulla oblongata is also the control centre for a number of vital body functions. These include: pacing of your heartbeat, controlling blood vessels & blood pressure, and setting the rate and depth of your breathing.
The pituitary gland is a small gland about the size of a pea, which is attached to the underside of the brain. It is made up of two halves, or lobes. The gland releases many important chemicals, called hormones into your blood stream. One hormone for example, affects the rate of your body's growth. many more control activities of other glands and, in turn, the release of many other essential hormones.
The hypothalamus is a part of your brain, about the size of a cherry, that is located behind your eyes. It is an important regulator of many of your body's automatic functions, including those of the hormonal system. Although small, the hypothalamus regulates the heart and blood pressure (making it 'pound' after a fright). It also controls body temperature by making you shiver and sweat, hunger and fullness, thirst and water balance, emotions and sleep.
This is where the spinal cord and the brain meet. Along with the medulla oblongata, it regulates breathing, making sure the tissues get enough oxygen.