red blood

• cellsBasic biological units
• hemoglobinErythrocyte's oxygen-binding protein
• oxygenElement eight, colorless gas
• veinsBlood-return tubes
• arteriesTubes carrying oxygenated blood

iron · crimson · circulation · marrow · pulse · transfusion · corpuscles · scarlet · bleeding · flow · heart · anemia · donor · clot · wound · life · warm · pumping