Foreign substances that invade the body and trigger an immune response. They can be proteins, polysaccharides, or other molecules found on the surface of bacteria, viruses, or other pathogens.
Lactic acid
A byproduct of anaerobic respiration in muscle cells, produced when there is not enough oxygen to support aerobic respiration. Accumulation of lactic acid can cause muscle fatigue and soreness.
Anaerobic respiration
A process of cellular respiration that occurs in the absence of oxygen, in which glucose is converted into pyruvate and lactic acid to generate ATP for energy.
Ventricular systole
The phase of the cardiac cycle where the ventricles contract and pump blood out to the body
