Septic shock is mainly due to a collapse in the blood circulation (the capillary system) due to blockage by blood cells - a process initiated by substances from the cells of the immune system via activation of coagulation. The normal function of the smallest blood vessels is to transport oxygen, nutrients and drugs to organs and tissues, and lead waste products away. While the offer of oxygen and nutrients to the organs decreases, the consumption of oxygen and nutrients increases due to fever and immune reactions.