A nurse has just started work in a busy emergency department. The first client she is assigned is a 34-year-old male who was in a motor vehicle accident. The client’s chest was crushed between his seat and the steering wheel and has a tension pneumothorax. He has also sustained a fracture of his T1 and has a partial severance of his spinal cord at that level. His upper and lower extremities are mottled in appearance with weak peripheral pulses; his JVP (jugular venous pressure) is high. Blood pressure is 86/50 mm Hg, and his pulse is 52 and regular. The client is difficult to arouse.

a. For the nurse to adequately care for this client, she must have a clear understanding of which concepts of circulatory function?