by Laura Garrow

Created on: September 02, 2007

It is important to understand the normal, overall function of the brain, the neurons, and the synapses before taking a glimpse into a brain without a lot of chemical reactions occurring.

"The human brain is our most powerful organ. It weighs only about three pounds, and has a texture similar to firm jelly. It has three main parts:
1. The cerebrum fills up most of our skull. Its main function involves remembering, problem solving, thinking, and feeling. It also controls movement.

2. The cerebellum is at the back of our head under the cerebrum. It controls coordination and balance.
3. The brain stem sits beneath your cerebrum in front of your cerebellum. It connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate and blood pressure.
Our brain is nourished by blood vessels. With each heartbeat, arteries carry about 20 to 25 percent of our blood to our brain, where billions of cells use about 20 percent of the oxygen and fuel our blood carries to them. When we are thinking hard, our brain may use up to 50 percent of the fuel and oxygen." (Inside the Brain, 2006).

The brain has a wrinkled surface that contains a specialized outer layer of the cerebrum called the cortex. Specific regions of the cortex:
Interpret sensations from your body, sights, sounds and smells from the outside world.
Generate ideas, solve problems and make plans.
Form and keep memories.
Control voluntary movement.
(Inside the Brain, 2006)

The human brain is divided into right and left halves. The left half of the brain is believed to control movement on the body's right side. The right half is believed to control the body's left side. In most people, the language area is mainly on the left side of the brain. (Inside the Brain, 2006)

An adult brain contains around 100 billion neurons, with branches that connect at more than 100 trillion points. This is called a "neuron forest." Signals connecting through the neuron forest form our memories, thoughts, and feelings. Neurons are the main kind of cell damaged and destroyed by Alzheimer's disease. Signals that form memories and thoughts move through an individual nerve cell as a tiny electrical charge. Nerve cells connect to one another at synapses. When a charge reaches a synapse, it may trigger the release of neurotransmitters. The neurotransmitters travel across the synapse, carrying signals to other cells. (Inside the Brain, 2006)

Alzheimer's disease disrupts the way electrical charges travel within

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