Answer the questions

What is the function of the nervous system?

What transmits electric signals?

How do they call a cell body?

What serves as input channels and output channels?

What is continuous conduction?

Name the four major brain divisions?

What does the cerebrum control?

What are gyri and sulci?

What controls many body activities that affect homeostasis (maintenance of a stable internal environment in the body)?

What does the hypothalamus do when it detects certain body changes?

What is the most dorsal (posterior) portion of the diencephalon?

What is the center for visual and auditory reflexes?

What is so peculiar about the white matter of the spinal cord?

What are the two parts of the PNS?

What does the PNS include?

What can a neuron be compared to?

What is longer: axon or dendrite?

What is a synapse?

Why are some axons partially coated with myelin sheaths?

How are the two parts of the cerebrum called?

What is the cerebral cortex composed of?

What forms the central part of the brain?

What is the main neural control center (brain part that controls endocrine glands)?

What produces and regulates production of antidiuretic hormone (ADH) and oxytocin?

What are the similarities between the cerebrum and the cerebellum?

What lies below the pons?

What does the peripheral nervous system include?

STROKE

A stroke is an interruption of the blood supply to any part of the brain. A stroke is sometimes called a "brain attack."

CAUSES, INCIDENCE, AND RISK FACTORS

Every 45 seconds, someone in the United States has a stroke. A stroke can happen when:

A blood vessel carrying blood to the brain is blocked by a blood clot. This is called an ischemic stroke.

A blood vessel breaks open, causing blood to leak into the brain. This is a hemmorhagic stroke.

If blood flow is stopped for longer than a few seconds, the brain cannot get blood and oxygen. Brain cells can die, causing permanent damage.

Ischemic stroke

This is the most common type of stroke. Usually this type of stroke results from clogged arteries, a condition called atherosclerosis. (See stroke secondary to atherosclerosis.) Fatty deposits and blood platelets collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. Often, the plaque causes the blood to flow abnormally, which can cause the blood to clot. There are two types of clots:

A clot that stays in place in the brain is called a cerebral thrombus.

A clot that breaks loose and moves through the bloodstream to the brain is called an cerebral embolism.

Another important cause of cerebral embolisms is a type of arrhythmia called atrial fibrillation. Other causes of ischemic stroke include endocarditis and the use of a mechanical heart valve. A clot can form on the artificial valve, break off, and travel to the brain. For this reason, those with mechanical heart valves must take blood thinners.

HEMORRHAGIC STROKE

A second major cause of stroke is bleeding in the brain hemorrhagic stroke. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.

STROKE RISKS

High blood pressure is the number one reason that you might have a stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.

Certain medications increase the chances of clot formation, and therefore your chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.

Men have more strokes than women. But, women have a risk of stroke during pregnancy and the weeks immediately after pregnancy.

Cocaine use, alcohol abuse, head injury, and bleeding disorders increase the risk of bleeding into the brain.

SYMPTOMS

The symptoms of stroke depend on what part of the brain is damaged. In some cases, a person may not even be aware that he or she has had a stroke.

Usually, a SUDDEN development of one or more of the following indicates a stroke:

1. Weakness or paralysis of an arm, leg, side of the face, or any part of the body

2. Numbness, tingling, decreased sensation

3. Vision changes

4. Slurred speech, inability to speak or understand speech, difficulty reading or writing

5. Swallowing difficulties or drooling

6. Loss of memory

7. Vertigo (spinning sensation)

8. Loss of balance or coordination

9. Personality changes

10. Mood changes (depression, apathy)

11. Drowsiness, lethargy, or loss of consciousness

12. Uncontrollable eye movements or eyelid drooping

If one or more of these symptoms is present for less than 24 hours, it may be a transient ischemic attack (TIA). A TIA is a temporary loss of brain function and a warning sign for a possible future stroke.

SIGNS AND TESTS

In diagnosing a stroke, knowing how the symptoms developed is important. The symptoms may be severe at the beginning of the stroke, or they may progress or fluctuate for the first day or two (stroke in evolution). Once there is no further deterioration, the stroke is considered completed.

During the exam, your doctor will look for specific neurologic, motor, and sensory deficits. These often correspond closely to the location of the injury in the brain. An examination may show changes in vision or visual fields, abnormal reflexes, abnormal eye movements, muscle weakness, decreased sensation, and other changes. A "bruit" (an abnormal sound heard with the stethoscope) may be heard over the carotid arteries of the neck. There may be signs of atrial fibrillation.

Tests are performed to determine the type, location, and cause of the stroke and to rule out other disorders that may be responsible for the symptoms. These tests include:

1. Head CT or head MRI -- used to determine if the stroke was caused by bleeding (hemorrhage) or other lesions and to define the location and extent of the stroke.

2. ECG (electrocardiogram) -- used to diagnose underlying heart disorders.

3. Echocardiogram -- used if the cause may be an embolus (blood clot) from the heart.

4. Carotid duplex (a type of ultrasound) -- used if the cause may be carotid artery stenosis (narrowing of the major blood vessels supplying blood to the brain).

5. Heart monitor -- worn while in the hospital or as an outpatient to determine if a heart arrhythmia (like atrial fibrillation) may be responsible for your stroke.

6. Cerebral (head) angiography -- may be done so that the doctor can identify the blood vessel responsible for the stroke. Mainly used if surgery is being considered.

7. Blood work may be done to exclude immune conditions or abnormal clotting of the blood that can lead to clot formation.

TREATMENT

A stroke is a medical emergency. Physicians have begun to call it a "brain attack" to stress that getting treatment immediately can save lives and reduce disability. Treatment varies, depending on the severity and cause of the stroke. For virtually all strokes, hospitalization is required, possibly including intensive care and life support.

The goal is to get the person to the emergency room immediately, determine if he or she is having a bleeding stroke or a stroke from a blood clot, and start therapy -- all within 3 hours of when the stroke began.