Why is it important for your heart to keep oxygen rich blood seperate from oxygen poor blood?

Which finger should not be used when measuring heart rate?

Felicia has a respiratory infection and has been coughing up a lot of mucus. she knows this means that her respiratory system is working to restore balance by getting rid of the invasive materials from her lungs. how does this happen?

Which of the following methods had the highest risk of transmitting hiv? a) oral sex b) sharing needles c) sweat d) preseminal fluid