Riddles in the dark

I'm the river that sustains you.
I'm the cell that still contains you.
I'm the line that binds your kin.
I'm the source that lies within.

When I'm hot, the anger rises.
When I'm cold, it paralyzes.
When I race, the throbbing shakes you.
When I halt, the reaper takes you.

I can cure, and I can kill.
I spread disease; I stop the chill.
I pound. I run. I spill. I gush.
I circulate. I freeze. I rush.

I can make the pressure soar.
I can thrill the carnivore.
I will go straight to your head,
And never stop until you're dead.

Answer: blood