During prenatal growth, the nervous system experiences many changes to gain its compound structure. The events of this early development include the growing of billions of neurons, axons, and the formation of thousands of synapses. The cells in the nervous system are a special type and continue to grow during the organisms life. There are approximately 100 billion cells in the nervous system. …show more content…
The embryo is composed of of three layers that go through many changes to form organs, bones, muscles, and skin, or neural tissue. After the fetus is conceived it takes three to four weeks before one of the three cell layers begins to thicken and builds up along the middle. Once the ectoderm (the outer most layer of cells to form) starts to form neural tissue, signals will determine which type of brain cell forms. The Nervous System includes The Central Nervous System and The Peripheral Nervous System. The Central Nervous System (CNS) consists of the spinal cord and the brain. The brain is in the skull and is shaped like a mushroom. It weighs about 1.3 to 1.4 kg and it has neurons in it supporting cells called the glia ("What is the Nervous System" 1). Glia are connective tissue that have many different cells associated with neurons. The brain is made of of four basic parts: the brain stem, the cerebrum, the cerebellum, and the diencephalon. The brain stem is found in the space separating the pons and the spinal cord and is only about one inch long. The cerebrum is the largest