Final answer:
Healthy individuals have very low, often undetectable levels of troponin in their blood. Troponin increases significantly when there is cardiac muscle cell damage, such as from a heart attack. Cardiac cells have limited repair abilities, and scar tissue from heart damage can impair heart function.
Step-by-step explanation:
Typically, healthy individuals without cell damage have very low levels of troponin in their blood, often undetectable with standard testing. Troponin is a protein complex involved in muscle contraction and is found in skeletal and heart (cardiac) muscle. When cardiac muscle cells are damaged, as in the case of a myocardial infarction (heart attack), troponin levels in the blood can increase significantly, which is why troponin levels are often measured to diagnose heart attacks. Although damaged cardiac muscle cells have limited self-repair abilities, some stem cells in the heart can potentially replace dead cells. However, these new or repaired cells generally do not function as well as the original cells, leading to reduced cardiac function. In severe cases, such as an MI, the dead cells are usually replaced by scar tissue, which does not contract like normal cardiac muscle tissue, further impairing heart function.