4. [Total: 23 pts] Cardiac output and venous return The figure below displays the cardiac output (Qc) and venous return (Q₂) curves that represent the steady state characteristics of the heart

and the rest of the circulation of a subject who is bleeding badly from a knife wound in the abdomen. Point N shows the steady state operating point of the system under normal circumstances prior to the stabbing and subsequent bleeding. Venous return and cardiac output (mL/min) 2800 2400 2000 1600 1200 800F 400 E 0 G -8 B D -4 0 4 8 Right atrial pressure (mmHg) a) [3 pts] Bleeding reduces blood volume and increases circulatory resistance. Which curve (A, B, C, D, E, F or G) best represents these changes from the normal case? Briefly explain the reason for your selection. 12/nb) [5 pts] From the information displayed in the figure, provide a rough estimate of the total volume of blood lost, assuming that the sum of arterial and venous compliances is 0.53 L-mmHg¹. Briefly explain how you arrived at your answer. c) [4 pts] In the compensated stage of shock from the bleeding, the heart becomes hypereffective (i.e., it generates a higher cardiac output for the same Pra). Label on the figure "c", the new steady state equilibrium values of Pr. and cardiac output in the compensated stage of shock following blood loss. Briefly explain your answer. d) [3 pts] If this subject remains in this state without medical care, the irreversible stage of shock sets in. The heart is no longer able to sustain its hypereffective performance and deteriorates progressively. Which curve (A, B, C, D, E, F or G) best represents this situation? Briefly explain your selection. Label on the figure "d", the new steady state equilibrium values of Pra and cardiac output in the irreversible stage of shock./ne) [4 pts) Assuming arterial pressure (PA) to be 40 mmHg and pleural pressure (Pi) to be -4 mmHg, provide your best estimate of what the ratio of systolic to diastolic compliance (Cs/Co) of the heart would be in the irreversible stage of shock from the bleeding, based the information displayed in the figure. f) [4 pts] if the subject were to receive blood transfusion at the irreversible stage of shock, can the blood transfusion restore the cardiac output to the normal level? Assume that the body has not yet adjusted to the replenished blood volume. Explain your answer.