When blood returns to the heart, it follows a complicated pathway. If you were in the bloodstream, you would follow the steps below one by one. Oxygen-poor blood (shown in blue) flows from the ...

Human blood is red because hemoglobin, which is carried in the blood and functions to transport oxygen, is iron-rich and red in color. Octopuses and horseshoe crabs have blue blood. This is ...

The physiological mechanisms that underpin human colour vision have ... on heart rate and blood pressure: red light does seem to raise heart rate, while blue light lowers it.

When blood returns to the heart, it follows a complicated pathway. If you were in the bloodstream, you would follow the steps below one by one. Oxygen-poor blood (shown in blue) flows from the ...