Heart attacks primarily relate to cellular respiration rather than photosynthesis. The discussion clarifies that heart attacks result from issues with nerve conduction or blood supply to the heart muscle, leading to oxygen deprivation. This lack of oxygen affects cellular respiration in heart cells, as they require oxygen to produce energy. Photosynthesis, occurring in plants, is not directly connected to heart attacks, as it involves converting light energy into chemical energy, a process not relevant to animal physiology. The link between heart attacks and cellular respiration centers on the impact of oxygen deprivation on energy production in muscle cells.