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from Guyton and Hall textbook of medical physiology, 4th South Asia edition write a 5 mark short note of the following questions oxygen debt

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Guyton Hall Medical Physiology oxygen debt exercise definition

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Oxygen Debt

Definition:
Oxygen debt is the extra amount of oxygen consumed after strenuous exercise, above the normal resting requirement, to restore the body to its pre-exercise metabolic state.
During heavy exercise, the immediate oxygen requirement of skeletal muscle exceeds oxygen delivery. The body therefore uses stored oxygen and anaerobic energy systems. After exercise stops, oxygen uptake remains elevated to replenish these stores and remove the effects of anaerobic metabolism.
Basis and amount:
Normally, the body has about 2 L of stored oxygen:
  • About 0.5 L in the lungs
  • About 0.25 L dissolved in body fluids
  • About 1 L combined with haemoglobin in blood
  • About 0.3 L stored mainly as myoglobin-bound oxygen in muscle
During heavy exercise, most of this is used within about a minute. Subsequently, extra oxygen is required to restore these stores and to reconstitute depleted energy systems. In the example described by Guyton and Hall, the total oxygen debt is approximately 11.5 L.
Components:
  1. Alactacid oxygen debt - about 3.5 L
    This is repaid soon after exercise. It restores:
    • Oxygen stores in lungs, blood, and myoglobin
    • ATP and phosphocreatine (phosphagen) stores in muscle
  2. Lactic acid oxygen debt - about 8 L
    This is repaid more slowly, over roughly 40 minutes in the illustrated example. It is used for removal of accumulated lactic acid:
    • A small portion is converted to pyruvate and oxidized by tissues.
    • Most is converted to glucose in the liver, which can help restore muscle glycogen.
Thus, after exercise, ventilation and oxygen consumption remain increased initially at a high rate and then decline gradually as lactic acid is cleared. Oxygen debt permits brief, intense muscular activity in which energy demand temporarily exceeds immediate aerobic oxygen supply.
Source: Guyton and Hall Textbook of Medical Physiology, 4th South Asia Edition, Chapter 85, “Recovery of the Aerobic System After Exercise,” p. 1062.
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