Final answer:
To treat a severely dehydrated patient, intravenous fluids such as an ordinary NaCl solution or a mixture of isotonic saline and sodium lactate are used to replenish lost electrolytes and fluids. Endocrine responses, including the angiotensin-renin-aldosterone mechanism and production of EPO, assist in restoring blood volume.
Step-by-step explanation:
To correct dehydration in a human patient who is nearly unresponsive and unable to increase fluid intake orally, intravenous fluids are often necessary. The type of intravenous fluid given depends on the specific electrolyte and fluid needs of the patient. For general hydration, a common solution is an ordinary NaCl solution, which can replenish lost sodium and chloride ions. If the patient's fluid excretion has been high in sodium and bicarbonate, then a mixture of 2/3 isotonic saline and 1/3 sodium lactate may be more appropriate, as it can better balance electrolyte losses.
Further endocrine processes are crucial in aiding the restoration of blood volume. The angiotensin-renin-aldosterone system will stimulate the thirst mechanism to encourage fluid intake if the patient is capable, increase renal reabsorption of sodium and water to minimize urine output, and trigger the production of erythropoietin (EPO), which promotes the formation of red blood cells to enhance oxygen delivery and overall blood volume.