Blood

How much your blood really costs

In the US, donating plasma twice a week can earn you $400 a month. But this system only works by targeting people who need the money most. Plasma clinics are placed in low-income zip codes, and frequent donation may increase health risks.

Blood transports oxygen and vital nutrients throughout the body

Blood is the most vital substance in a body, ferrying oxygen, nutrients, and hormones to cells in need while regulating body temperature and collecting cellular waste and byproducts, such as carbon dioxide, for removal. Every adult human has over a gallon of the red liquid coursing through their veins.

The earliest known cardiovascular system dates to 520 million years ago

The earliest evidence of a cardiovascular system and blood-like substance may date back to the Cambrian period in an ancient arthropod. This 2014 academic article includes images of the ancient cardiovascular system, which remains one of the most detailed samples of Cambrian arthropod anatomy.

Blood evolved many times over hundreds of millions of years

The earliest evidence of a blood-like substance comes from ancient arthropods, which appear to have had copper-based blood. In the 500 million years since then, some creatures have grown to rely on other variants, such as humanity's iron-based blood.

Exploring the microscopic composition of blood

Visually, blood looks like a single, red fluid. Zooming in, it is one of the richest substances known, with hemoglobin, plasma, proteins, red and white blood cells, platelets, and more.

'Buffy coats': The 1% of blood that helps fight off disease

When blood is centrifuged, white blood cells and platelets form a layer called the buffy coat between the plasma and red blood cells. This layer makes up less than 1% of blood, but its heightened leukocyte concentration makes it useful for toxicology research.

Bone marrow generates roughly 500 billion new blood cells each day

Some of our bones are stuffed to the brim with a fatty, jam-like substance called marrow. Bone marrow comes in yellow and red, with the latter responsible for producing new blood cells, and has become critical in treating diseases like leukemia.

New blood cells are created by hematopoietic stem cells

Blood is made up of several cells with various functions and short lifespans, so the body must have a constant supply of replacements. These replacements are created by hematopoietic stem cells, rare cells that live in bone marrow and can regenerate themselves and blood cells.

The proteins and sugars on the surface of your blood cells determine your blood type

The antigens dotting the outside of a red blood cell determine blood type. That's why the four main blood types are A, B, AB, and O, each with positive and negative variations. Secondly, the presence or absence of the Rh factor protein determines whether the type is positive or negative.

The rarest blood type in the world

Rh-null, also known as “golden blood,” is a blood type so rare, fewer than 50 people are known to have it. It lacks all 61 Rh antigens, making it a universal donor for rare Rh cases, but a nightmare in emergencies, since only Rh-null can be given back.