We can answer this question by looking at the differences between the first, second and third layers of our skin.
Trying a new exercise routine? Strapping on a new wearable monitor? An expert in human physiology explains the ins and outs of your heart rate and why it's a valuable number to understand.
Every person's blood is identified by type. Why does this matter?
The body tries to plug a wound quickly to stop germs getting in through broken skin and making you sick. But behind the scenes, your blood is working hard to repair a wound.
The white blood cells act as an army of fighting cells, protecting your body from bad cells known as germs. White blood cells can capture germs and even swallow them.
Most of the time, different parts of your nervous system work in balance. But sometimes things can get out of whack – and that's when you might end up experiencing what medics call syncope.
Platelets heal wounds. But they also seem to play a paradoxical role in both promoting and inhibiting the growth of solid tumors.
Ants have something similar to blood, but it's called haemolymph. Some insects use it in unusual ways. When threatened by a predator, blister beetles can squirt haemolymph from their knees.
Canada suffers a shortage of vital blood plasma. Paying donors, through a non-profit like Canadian Blood Services, would secure a local supply without lining the pockets of corporate shareholders.
Figuring out what causes diseases like autism, schizophrenia and depression is tricky. Now Stanford University researchers are turning blood into brain cells to study these diseases in a dish.
Your blood is red;
it's never blue.
Because of hemoglobin;
and the view through tissue.
New research shows green-blooded skinks have evolved multiple times, which could help lead to explanation as to why.
Recent scientific studies have claimed that transfusions of blood from teenagers can help delay or reverse the ageing process. Do they stack up?
Blood is red, but our veins are blue. Or are they?
New mouse model study sheds light on why alcohol is so harmful.
Much of the Harry and Meghan coverage has ignored the royal family's complicated history with race and "blood" and its insistence on continuing outdated traditions.
Be it because of concerns over big femcare, landfill, cost, toxic ingredients or toxic shock syndrome, some menstruators seek solutions outside of the Kotex box. These are those choices.
Hepatitis viruses are serious infections that damage the liver. There is an urgent need to deal with increased Hepatitis B infections in Kenya.
Contemporary artists from Judy Chicago to Stelarc have made art from blood. And an exhibition at Melbourne's new Science Gallery addresses our ambivalent attitudes to this life-giving fluid.
An overview of the most common problems in our blood: bleeding disorders, clotting disorders and cancer.