According to the national institute of health, shock happens when blood pressure drops and blood and oxygen flow decreases to your organs and tissues. causes of shock include internal or external bleeding, dehydration, burns, or severe vomiting and/or diarrhea. all of these involve the loss of large amounts of body fluids. shock often accompanies injury. why would the loss of large amounts of body fluids result in low blood pressure? it will decrease blood volume, increasing the flow rate of blood. it will increase blood volume, increasing the flow rate of blood. it will decrease blood volume, reducing the flow rate of blood. it will increase blood volume, reducing the flow rate of blood.