Human Biology

1.50. Diseases of the Nervous System http://www.ck12.org

are more commonly due to muscle tension. A tension headache occurs when muscles in the shoulders, neck, and
head become too tense. This often happens when people are “stressed out.” Just trying to relax may help relieve this
type of headache (Figure1.100). Mild pain relievers such as ibuprofen may also help.

FIGURE 1.100

Sometimes relaxation is the best

“medicine” for a tension headache and to

help muscles get rid of pain.

Amigraineis a more severe type of headache. It occurs when blood vessels in the head dilate, or expand. This may
be triggered by certain foods, bright lights, weather changes, or other factors. People with migraines may also have
nausea or other symptoms. Fortunately, migraines can often be relieved with prescription drugs.

There are many other nervous system diseases. They include multiple sclerosis, Huntington’s disease, Parkinson’s
disease, and Alzheimer’s disease. However, these diseases rarely, if ever, occur in young people. Their causes and
symptoms are listed below (Table1.8). The diseases have no known cure, but medicines may help control their
symptoms.

TABLE1.8:Incurable Nervous System Diseases

Disease Cause Symptoms

Multiple Sclerosis The immune system attacks and

damages the central nervous sys-

tem so neurons cannot function nor-

mally.

Muscle weakness, difficulty mov-

ing, problems with coordination,

difficulty keeping the body bal-

anced

Huntington’s Disease An inherited gene codes for an ab-

normal protein that causes the death

of neurons.

Uncontrolled jerky movements, loss

of muscle control, problems with

memory and learning

Parkinson’s Disease An abnormally low level of a neu-

rotransmitter affects the part of the

brain that controls movement.

Uncontrolled shaking, slowed

movements, problems with

speaking

Alzheimer’s Disease Abnormal changes in the brain

cause the gradual loss of most nor-

mal brain functions.

Memory loss, confusion, mood

swings, gradual loss of control over

mental and physical abilities

Vocabulary

• cerebral palsy: Disease caused by injury to the developing brain that results in impaired muscle coordination.


• encephalitis: Infection of the brain that can cause fever, headache, drowsiness, and confusion.