Why can LDLs be a proplem?

Answer 1

LDL (low-density lipoprotein) is a type of lipid carrier made up of proteins and lipids. The protein-lipid complex enables lipids to be transported in the bloodstream from liver, its site of synthesis, to other parts of the body where lipids are stored or used. The difference between LDL and other types of lipoproteins is in its significantly higher content of cholesterol. Normally cholesterol is essential to maintaining cell membrane fluidity, but in this case, cholesterol actually causes a disease known as atherosclerosis (Greek for porridge-scar-disease).

Atherosclerosis:

LDL particles (especially small ones) are prone (not by design) to being captured and entangled by arterial epithelial cells that express certain glycoproteins. These trapped particles aggregate inside and outside the epithelial cells to such an extent that it recruits leukocytes of the immune system such as neutrophils and macrophages to the site to try to clean it up. However, these cell do not have the appropriate enzymes to break down cholesterol (no human cell does and cholesterol is normally excreted in bile) and after they engulf too much cholesterol they die. This eventually leads to a noticeable lesion on the vessel wall and this structural anomaly can trap more LDL particles and attract more leukocytes. This vicious cycle continues and the vessel wall smooth muscle proliferates to contain the growing pool of lipids and dead cells. Several bad effects can result from this. First, the narrowing of blood vessel can result in organs not getting sufficient blood supply, and second, a bump in a blood vessel wall can induce more turbulent flow than laminar flow, and this turbulence can cause the activation of platelets, which aggregate and can clot small vessels, completely cutting off blood supply to downstream tissues. However, the worst happens when the bulge can no longer be contained by the smooth muscle sheath and the sheath bursts, spilling a large amount of stored lipids and dead cells. The effect of this is usually catastrophic, resulting in the very quick blockage of multiple blood vessels because of a great aggregation of plateplets induced by these substances. If any of these vessels happen to carry blood to the heart or the brain, a heart attack or a stroke results. These conditions are life-threatening and can result in death very quickly if untreated. Even if care was provided in time, treatment is still very difficult and cellular damage to the heart or brain cannot be repaired by any means scientifically available.