An Introduction to the Brain and Nervous System

Published by Steve Hedberg on May 18, 2009 Under dementia

brainThe brain, which weighs about 3 pounds, is made up of approximately 100 billion different neurons. Electrical impulses travel across these neurons, forming a network that reaches to even the farthest appendage.

The neural network, or nervous system, is responsible for our movements, talents, thoughts, dreams, and personality. It is also responsible for a number of other background functions, such as regulating body temperature, controlling respiration, and thousands of other tasks, which are preformed all while allowing an individual to learn and feel.

The brainstem, or cerebellum, is located at the base of the brain and is connected to the spinal cord. The spinal cord serves as a central conduit, instantly transmitting impulses to the brain. It also is responsible for a number of the body’s reflexes. The brainstem serves as the bodies life support system, handling the heart, breathing, and sleeping.

Emotions and the Limbic System

Above the cerebellum lies the limbic system, which is also found in other mammals and provides us with our most basic physical and emotional urges, such as rage, fear, and sexual desire. However, the limbic system is connected to other brain matter, which allows us to express these urges using cognitive thought.

Four Parts of the Limbic System

There are four major components of the limbic system, including the amygdala, hippocampus, hypothalamus, and thalamus.

The amygdala is shaped like an almond and is responsible for emotions, partially aggression.

The hippocapus helps to process information, comparing impulses against stored responses, making it critical for being able to attribute meaning to the symbols and events that occur in day to day living.

The hypothalamus plays a big part in our moods, while regulating our food and water intake accordingly.

The thalamus, which is nearer to the center of the brain, processes all of our senses, with the exception of smell. It acts as a switchboard, connecting our senses with the part of our brain used to interpret these senses.

The Cerebrum: Two Hemispheres

The cerebrum, which is the largest part of the human brain, surrounds the limbic system and is where the electrical nerve impulses are transformed into ideas. The outer layer of the cerebrum is called the the cerebral cortex, and unlike most other mammals, the human cerebral cortex is divided into two halves, which are commonly called hemispheres, each having their own purpose and abilities.

The right hemisphere helps process colors, visualization, and is thought of as the artistic portion of the brain. The left hemisphere is used to understand words and generate speech patterns, so while it still is used creatively, it also processes analytical tasks, like mathematics.

Aging and the Deterioration of the Brain

With age, the neurons in the body begin to die. Under normal circumstances, the neurons die off at approximately 20 million per year. This typically does not effect our intelligence, such as speech or the ability to understand or form complex ideas. It does, however, affect the speed at which these concepts are processed.

This is a normal part of aging and most healthy individuals in their seventies do not have a distinguishable loss of blood flow or oxygen loss. This is important to note, because even though the brain is relatively small, it uses approximately 20 percent of the body’s blood and oxygen.

Since most healthy individuals do not experience a significant reduction in their cognitive abilities, even into their seventies, senility and mental deterioration are not considered natural or even a normal part of aging.

Instead the loss of mental faculties and senility are typically linked to severe head trauma, malnutrition, alcoholism, or the side effects of drugs. Disease also plays a role in senility, with strokes and Alzheimer’s often leading to senility.

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