What is ischemia?

• A. Inadequate blood circulation causing necrosis.
• B. Excess blood flow to tissue.
• C. Increased heart rate.
• D. Fluid buildup in joints.

Answer: (A)

Ischemia is reduced blood flow to a tissue, so the oxygen and nutrients delivered by the blood are insufficient for the tissue’s metabolic needs. When perfusion falls short, cells can’t run on aerobic respiration and must rely on less efficient anaerobic metabolism, leading to less ATP production and buildup of metabolic byproducts. If blood flow isn’t restored, this cellular stress can progress to injury and eventually cell death (necrosis) in the affected area. This concept is distinct from simply having excess blood flow (hyperemia), an increased heart rate (a separate physiologic response), or fluid buildup in joints (edema).