The human brain is believed to function in a complex chemical environment through various types of neurons and neurotransmitters. Neurons are brain cells, numbering in the billions, which are capable of instant communication with each other through chemical messengers called neurotransmitters. As we live our lives, brain cells are constantly receiving information about our environment. The brain then attempts to make an internal representation of our external world through complex chemical changes.
Neurons (Brain Cells)
The center of the neuron is called the cell body or soma. It contains the nucleus, which houses the cell’s deoxyribonucleic acid (DNA) or genetic material. The cell’s DNA defines what type of cell it is and how it will function. At one end of the cell body are the dendrites, which are receivers of information sent by other brain cells (neurons). The term dendrite, which comes from a Latin term for tree, is used because the dendrites of a neuron resemble tree branches. At the other end of the cell body is the axon. The axon is a long tubular fiber that extends away from the cell body. The axon acts as a conductor of electrical signals. At the base of the axon are the axon terminals. These terminals contain vesicles where chemical messengers, also known as neurotransmitters, are stored.
Neurotransmitters (Chemical Messengers)
It is believed that the brain contains several hundred different types of chemical messengers (neurotransmitters). Generally, these messengers are categorized as either excitatory or inhibitory. An excitatory messenger stimulates the electrical activity of the brain cell, whereas an inhibitory messenger calms this activity. The activity of a neuron (brain cell) is largely determined by the balance of these excitatory and inhibitory mechanisms. Scientists have identified specific neurotransmitters that are believed to be related to anxiety disorders. The chemical messengers that are typically targeted with medications commonly used to treat the panic disorder include:
Serotonin. This neurotransmitter plays a role in modulating a variety of body functions and feelings, including our mood. Low serotonin levels have been linked to depression and anxiety. The antidepressants called selective serotonin reuptake inhibitors (SSRIs) are considered to be the first-line agents in the treatment of panic disorder. SSRIs increase the level of serotonin in the brain, resulting in decreased anxiety and inhibition of panic attacks. Norepinephrine is a neurotransmitter that is believed to be associated with the fight or flight stress response. It contributes to feelings of alertness, fear, anxiety, and panic. Selective serotonin-norepinephrine reuptake inhibitors (SNRIs) and tricyclic antidepressants affect the serotonin and norepinephrine levels in the brain, resulting in an anti-panic effect. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that acts through a negative feedback system to block the transmission of a signal from one cell to another. It is important for balancing the excitation in the brain. Benzodiazepines (anti-anxiety drugs) work on the GABA receptors of the brain inducing a state of relaxation.
How Neurons and Neurotransmitters Working Together
When a brain cell receives sensory information, it fires an electrical impulse that travels down the axon to the axon terminal where chemical messengers (neurotransmitters) are stored. This triggers the release of these chemical messengers into the synaptic cleft, which is a small space between the sending neuron and the receiving neuron. As the messenger makes its journey across the synaptic cleft, several things may happen: For optimal brain function, neurotransmitters must be carefully balanced and orchestrated. They are often interconnected and rely on each other for proper function. For example, the neurotransmitter GABA, which induces relaxation, can only function properly with adequate amounts of serotonin. Many psychological disturbances, including panic disorder, may be the result of poor quality or low quantities of certain neurotransmitters or neuron receptor sites, the release of too much of a neurotransmitter or the malfunctioning of the reuptake mechanisms of the neuron.
