<prompt> First response to decreased blood volumeIncreased hea rateTachypneaHypotensionDisorientation  <response>: Baroreceptor reflex is an immediate compensatory mechanism in shock. There is stimulation of aerial baroreceptors and so sympathetic output is increased leading to vasoconstriction and reflex tachycardia. Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no. 184 