According to the Bohr model, the wavelength of the light emitted by a hydrogen atom when the electron falls from a high energy (n = 4) orbit into a lower energy (n = 2) orbit.
A network of arteries and veins also carry blood throughout the body: Arteries transport blood from the heart to the body tissues. Veins carry blood back to the heart.ow the heart works. The heart is a large, muscular organ that pumps blood filled with oxygen and nutrients through the blood vessels to the body tissues. It's made up of: Four chambers. The two upper chambers, the atria, receive and collect blood.
There are three main types of blood vessels: Arteries. Arteries carry oxygen-rich blood away from the heart to all of the body's tissues. They branch several times, becoming smaller and smaller as they carry blood farther from the heart and into organs. Capillaries. These are small, thin blood vessels that connect the arteries and the veins.