In high school, you probably learned that trigonometric functions – like sine, cosine and tangent –can be derived, geometrically, from a circle (hence why trig functions are also known as “circular” ...

Our heart and lungs circulate oxygen throughout our blood vessels to keep cells alive. At the center of the circulatory system is the heart, which works with the lungs to constantly keep the body ...

Your heart is a muscular organ that helps circulate your blood, which delivers oxygen and nutrients to your tissues. There are four chambers and four valves in your heart, and each ensures proper ...

Check your knowledge of the heart and how blood is transported around the body by blood vessels ahead of your Higher Human Biology exam. Brush up on your knowledge of arteries, capillaries, veins and ...