« previous next »
« previous next »
 

Did you know?

Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.

Did you know?

When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.

Did you know?

Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.

Did you know?

Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.

Did you know?

There can actually be a 25-hour time difference between certain locations in the world. The International Date Line passes between the islands of Samoa and American Samoa. It is not a straight line, but "zig-zags" around various island chains. Therefore, Samoa and nearby islands have one date, while American Samoa and nearby islands are one day behind. Daylight saving time is used in some islands, but not in others—further shifting the hours out of sync with natural time.

Mammography. (a) A health-care professional assists the patient to ensure the breast is placed ideal Mammography. (a) A health-care professional assists the patient to ensure the breast is placed ideal
Booker T. Washington in his office at Tuskegee Institute, 1900. Washington chose a policy of accommo Booker T. Washington in his office at Tuskegee Institute, 1900. Washington chose a policy of accommo
The “Big Four” world leaders meet at the Hotel Crillon in Paris, 1919. From left to right (front row The “Big Four” world leaders meet at the Hotel Crillon in Paris, 1919. From left to right (front row
Each year, the leaders of the world’s eight most powerful nations meet in a secluded place to make ... Each year, the leaders of the world’s eight most powerful nations meet in a secluded place to make ...
Processes of Lightning Formation: Leaders, Strokes, and Flashes Processes of Lightning Formation: Leaders, Strokes, and Flashes
Processes of Lightning Formation: Leaders, Strokes, and Flashes Processes of Lightning Formation: Leaders, Strokes, and Flashes
Video: Five phases of cardiac cycle & Atrial contraction

For a complete list of videos, visit our video library