Drugs that affect the
nervous system have two primary effects: they impact the limbic system and
either promote or decrease the action of a particular neurotransmitter. One
such drug is nicotine, an alkaloid derived from tobacco. Nicotine causes
neurons to release dopamine in the central nervous system (CNS), while
stimulating post-synaptic receptors in the peripheral nervous system (PNS),
leading to increased activity. Nicotine also increases heart rate and blood
pressure, digestive tract mobility, and can even induce vomiting, as well as
causing water retention in the kidney.
Common nervous disorders
There are several
common nervous disorders, including Parkinson's disease, epilepsy, and
Alzheimer's disease.
Parkinson's
disease
Parkinson's disease is
caused by the death of cells in the brain that produce dopamine, resulting in
symptoms such as slowness of movement, tremors, and rigidity. While the disease
usually appears between the ages of 50 and 60, it progresses slowly, and patients
may live for many years. Head trauma can also cause Parkinson's disease.
Effective drugs for treating Parkinson's disease include L-dopa, carbidopa, and
glial-derived growth neurotrophic factor (GDNF), which boosts the uptake of
dopamine.
Epilepsy
Epilepsy is one of the
convulsive disorders of nerves, characterized by abrupt transient symptoms of
motor, sensory, psychic, or autonomic nature, frequently associated with
changes in consciousness. The disease is believed to be caused by sudden,
transient alterations in brain function associated with excessive rapid
electric discharges in gray matter. Emotional disturbances can play a
significant role in triggering seizures. Anticonvulsant drugs are used to treat
epilepsy, and patients should avoid alcohol as it can aggravate the condition.
Electroencephalography is an essential test in the study of epilepsy.
Alzheimer's
disease
Alzheimer's disease was
first discovered by Alois Alzheimer in 1907. It is characterized by a gradual
loss of reasoning that begins with memory lapses and ends with an inability to
perform daily activities. Alzheimer's disease affects two key parts of the
brain: the cortex of the cerebral hemisphere, which is the conscious part of
the brain, and the hippocampus, which is involved with memory. The disease is
difficult to diagnose because its symptoms are similar to those of other
diseases that cause dementia. However, brain tissue under a microscope shows
protein plaques accumulating outside brain cells and tangled deposits of protein
appearing inside the cells. Both plaques and tangles are caused by the
accumulation of abnormal proteins. There is evidence that high levels of
aluminum may contribute to the onset of the disease, but it appears that a
shortage of the neurotransmitter acetylcholine in the brain is a primary
factor. Drugs that enhance acetylcholine production are available for the
treatment of Alzheimer's disease.
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