The Nervous System

The brain is one large mass of tissue. It is divided into several parts that are difficult to see. The outside covering of the brain looks like a bunch of large worms all bunched together. This outside covering is called the cortex.

The cortex is divided into two sides, a left hemisphere and a right hemisphere. People who mostly use the left side of their brain are logical thinkers, they are good at subjects like math and science. People who mostly use the right hemisphere of their brain are creative; they are good at things like problem solving, art, and languages.

Underneath the cortex of the brain is the feeling part of your brain, the limbic system. This system controls your body temperature and your emotions, and it helps your thinking brain with memory and learning. The innermost part of the brain, the reptilian brain, is also called the brainstem. This is the part of the brain that controls things that you don't have to think about, like the involuntary muscles. The brain weighs about three pounds by the time we reach adulthood. We need our brains to talk, think, read, run, dream, color, cry, breathe, scream, wave, blink - basically everything we do!

Sites to see:

The Nervous System

The Control Center

Dragonfly Television Activities

Great site to learn more

Tasting Use paper cups and put into 1-salt, 2-coffee, 3-sugar, and 4-lemonUse a cotton swab. Dip one end into the lemon juice. Touch the swab to parts of the tongue Where did you feel the taste of sour? Have the children label a tongue.

	THE 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 (our memories).The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body
	SIZE OF THE HUMAN BRAINThe average human brain weighs about 3 pounds (1300-1400 g).At birth the human brain weighs less than a pound (0.78-0.88 pounds or 350-400 g). 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 BRAINThe 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 (medulla).
NOURISHMENT OF 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 (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 (CSF) surrounds the brain.
	THE NERVOUS SYSTEM The brain and spinal cord make up the central nervous system (CNS). 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.
	PROTECTION 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 (CSF) is a clear, watery liquid that surrounds the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts. The cranium (the top of the skull) surrounds and protects the brain. The spinal cord is surrounded by vertebrae (hollow spinal bones). Also, some muscles serve to pad and support the spine. More subtly, 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.

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