In which of the following structures is Na NOT returned to the blood?

which antigens and antibodies are present in each ABO blood type?

For each umbilical vessel and the major fetal blood vessels, state whether each vessel carries oxygen-rich, oxygen-poor or mixed blood, and explain why the different oxygen levels occur in these vessels.

After a man was stabbed in the chest, his face became blue and he lost consciousness from lack of oxygenated blood to the brain. The diagnosis was cardiac tamponade rather than severe blood loss through internal bleeding. What is cardiac tamponade, how did it cause the observed symptoms, and how is it treated?