When a man becomes aroused, his brain sends nerve impulses that increase blood flow to his penis. The blood fills the spongy chambers (corpora cavernosa) in the penis, causing it to expand and become rigid. The veins that would normally drain blood from the penis constrict, trapping the blood inside and maintaining the erection.

After ejaculation or when the man is no longer sexually aroused, the arteries narrow, the veins expand, and the blood drains out of the penis. The penis returns to its normal size and is no longer rigid.

• When atherosclerosis affects the arteries that supply blood to the heart, it can restrict blood flow to the heart muscle, causing heart pain (angina), irregular heartbeats (arrhythmia), and other problems. Plaque may damage the artery lining, causing blood clots that can block blood flow, which in turn may cause a heart attack and cause damage to the heart muscle. Atherosclerosis in the heart (coronary) arteries is called coronary artery disease.
• When atherosclerosis affects the arteries that supply blood to the brain, it may cause a transient ischemic attack (TIA) or stroke.
• Atherosclerosis can affect arteries in other parts of the body, such as the pelvis and legs, causing poor circulation, slower healing of skin injuries, and erection problems.

A major part of treating atherosclerosis and coronary artery disease involves lifestyle changes (such as quitting smoking) and medications to help reduce high cholesterol, control high blood pressure, and manage other factors that increase a person’s risk of heart attack, stroke, and other complications.

• Hardening of the arteries (atherosclerosis) in the penile arteries, which may block blood flow into the penis or into the arteries that fill the penile arteries.
• Side effects of medications that affect the blood vessels (such as some diuretics or other high blood pressure medications), which may interfere with the filling process.
• Leaking of blood from the spongy chambers (corpora cavernosa) in the penis to the veins that carry blood from the penis. This may lead to the inability to maintain an erection.

The effects of a stroke may be mild or severe and temporary or permanent, depending on which brain cells are damaged, how much of the brain is involved, and how quickly the blood supply is restored to the area.

Symptoms of a stroke are usually sudden and may include:

• Numbness, weakness, or lack of movement (paralysis) in the face, an arm, or a leg, especially on only one side of the body.
• Trouble seeing in one or both eyes.
• Confusion and difficulty speaking.
• Dizziness and a loss of balance or coordination.
• Vomiting.
• A sudden, severe headache.

A person with stroke symptoms needs immediate medical attention to help limit potential damage.