ABSTRACT
Blood, with its many components, plays manifold roles in our responses to high altitude, including changes in the immune system (see Chapter 19). In this chapter we shall limit ourselves to only two functions, oxygen transport and hemostasis. We shall describe both the acute alterations in the volume and composition of the blood following ascent to high altitude as well as the long-term increase in red cell mass (polycythemia), and how these changes serve to enhance oxygen transport from lung to tissue. Variability among individuals in both the regulation of blood composition as well as the patterns of adaptation to hypoxic stress will be emphasized. Further, we shall discuss how hypoxia alters blood clotting and clot lysis.
