Bloodstreams

All of us carry bits of our own genetic material—both DNA and its more evanescent cousin, RNA—around in our bloodstreams.

First, for a study published in 2013, they compared the many metabolites in the bloodstreams of twins and other, unrelated adults, most of whose lives differed wildly in terms of how much they worked out.

Whale starvation exacerbates the danger: Without enough food, whales resort to burning fat for energy, which releases more toxins into their bloodstreams.

In most reptilian species, there appears to be little, if any, mixing between the bloodstreams, so the aorta receives, essentially, only oxygenated blood.

Mixing of the two bloodstreams is minimized by the anatomy of the chambers.sfn Nervous and sensory systems The nervous system is basically the same as in other vertebrates, with a central brain, a spinal cord, and nerves throughout the body.