1) Describe in detail the protein structure of haemoglobin with emphasis on its organization which makes gas transport possible.

2) Compare and contrast the homeostatic regulation of blood calcium (calcemia) by the thyroid gland and parathyroid gland, respectively. Be complete in your answer and include the hormones that participate in this regulatory mechanism.

3) What is meant by the ABO+/- blood groups, and what cell types are classified under this category? Include in your answer any and all antigens and/or antibodies present in the cells or surrounding plasma. Which blood types are the universal donor and recipient and why? Finally, explain the cause and physiological consequences of a transfusion reaction.

4) Describe in detail the phenomena of hemostasis that result in the cessation of bleeding.