Science Buddies: "Ask an Expert"

Are atherosclerosis and hemophilia related? Are they the main causes of blood clots? Are these the two main causes which cause blood vessels to brake or erupt?

Great question, I like your line of thinking, but they are not related as far as I know. In fact while atherosclerosis can lead to sudden clots, hemophilia is a syndrome in which the blood cannot form a blood clot.

Atherosclerosis is a process in which lipids (fat) are deposited into the walls of your major arteries. Your body tries to remove those deposits, but the cells which are responsible become overwhelmed and die. As a result a plaque forms in your blood vessels. This causes the vessels to become narrow (also known as "sclerotic"). If this happens to a very important arterty such as the ones which supply blood to your heart muscles (the coronary arteries), then your demand for fresh blood could exceed the damaged vessel's ability to let blood flow (a disease called unstable angina). Atherosclerotic plaques can also burst open, like a pimple, and the junk which comes out can get stuck in a smaller vessel creating a clot. This will essentially suffocate the part of the body that vessel feeds. This will kill the tissue very quickly if it happens in the heart (this is a heart attack).

Hemophilia is a description of a person's blood's inability to clot. This can be due to one of many genetic mutations which effect a molecular signaling pathway called the "coagulation cascade". This "pathway" is a set of proteins in your cell which work together to form the proteins needed to form a blood clot. The purpose of this is so that if you cut yourself, the cells in the area have the ability to make puddy to clog up the holes so you won't bleed to death. Hemophiliacs have a problem with one of those signaling proteins, so they cannot start to form that puddy. As a result, they cannot form blood clots well.

Thank you. This really helped. Does atherosclerosis affect men more than it does to women? What exactly is unstable angina and is it a disease that affects the blood vessels in a major way?

No problem. Atherosclerosis does effect men more than women, and it has several strong genetic predispositions. High fat diets are a major risk factor as well as smoking and sedentary lifestyle. Unstable angina is the disease in which patients feel chest pain and breathlessness upon exertion. This is because when the patient does anything athletic, the heart has to pump faster which means it needs more oxygen to keep working. Since the coronary arteries are sclerotic (narrow), the blood supply cannot provide enough oxygen. This damages the heart muscle and results in chest pain (what we call angina). These atherosclerosis plaques can deposit in any arteries, but they do the most damage in the heart because of it's extreme oxygen demands. Similarly if a plaque breaks open and sends a clot up to the brain, this will result in a stroke. Think of heart attacks, unstable angina, or strokes as by products of the atherosclerosis.