Because that is where blood is... You can't exactly transfuse it into your liver or something because that's where blood goes in and it will come out old and used up. So they inject into veins so it goes to the heart and other vital organs... That's what I think anyway.
arteries and veins
what veins does it pass through
Irish blood runs through these veins
Veins have valves in them which help transport the blood.
The contraction of muscles and one-way valves in the veins help facilitate the flow of blood through the veins.
through your veins
By your heart pumping the blood through your veins.
The pressure your heart creates by pulsing, pumps blood through the veins
Your veins are running all throughout your body with blood running through them. And all the veins are connected the the heart.
Blood Travels through Veins
Yes, blood flows into the heart via veins. Blood flows away from the heart in aryteries.
Through both! The pulmonary veins carry oxygenated blood to the heart and then arteries carry it from the heart to the body as a whole. Veins return de-oxygenated blood to the heart.