Functions of the Brain
The human brain is a complex organ that allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives information, analyzes information, and stores information as memories.
Each time an impulse, or a message transmitted along nerve cells, travels along a nerve, a small amount of electricity is generated. The brain itself uses power equal to a 10-watt bulb. The electrical patterns that are produced by the brain’s nerve actions are called brain waves. The human body is actually made of water, minerals, and salts, making it a good conductor of electricity. That’s also why you shouldn’t touch power lines or play with sockets.
The millions of tiny electrical nerve signals continually moving in the brain cause electrical signals to pass through the bones of the skull and outward to the skin of the scalp and head. In 1875, Richard Caton first discovered these brain waves. His process, though, used electrodes that were actually inserted into the brain. In 1929, Hans Berger, detected the brain waves with electrodes on the outside of a person’s head.
Size of the Human Brain
The average human brain weighs about 3 pounds which is the approximate weight of the last Harry Potter hardback book.
At birth, the human brain weighs less than a pound. As a child grows, the number of cell remains relatively stable, but the cells grow in size and the number of connections increases. The human brain reaches its full size at about 6 years of age.
Composition of the Brain
The brain consists of gray matter (40%) and white matter (60%) contained within the skull. Brain cells include neurons and glial cells.
The brain has three main parts: the cerebrum, the cerebellum, and the brain stem, also called the medulla.
Nourishing the Brain
Although the brain is only 2% of the body’s weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. Blood vessels, including arteries, capillaries, and veins, supply the brain with oxygen and nourishment, and take away wastes. If brain cells do not get oxygen for 3 to 5 minutes, they begin to die.
Cerebrospinal fluid surrounds the brain.
The Nervous System
The brain and spinal cord make up the central nervous system. The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body.
The nerves that connect the CNS to the rest of the body are called the peripheral nervous system.
The autonomic nervous system controls our life support systems that we don’t consciously control, like breathing, digesting food, blood circulation, etc.
Protecting the Brain and Nervous System
The cells of the nervous system are quite fragile and need extensive protection from being crushed, being infected by disease organisms, and other harm. The brain and spinal cord are covered by a tough, translucent membrane, called the dura matter. Cerebrospinal fluid is a clear, watery liquid that surrounds the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). Cerebrospinal fluid cushions the brain and spinal cord from jolts.
The top of the skull, also known as the cranium, surrounds and protects the brain. The spinal cord is surrounded by hollow spinal bones called vertebrae. Also, some muscles serve to pad and support the spine.
The blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain.