Wednesday, December 17, 2008

Heart Attack

What causes a heart attack?
A heart attack occurs when the heart cannot pump enough blood through the body. The most common kind of heart attack is called myocardial infarction – an area of dead tissue in the heart muscle -- which happens when a condition called coronary artery thrombosis blocks the flow of oxygen-bearing blood to heart muscle cells and they die.

This usually happens in two stages.
First, in a process that can take years, vessels carrying blood to the heart muscle tissue become clogged with plaque, which contains cholesterol – a fatty substance found in food and also produced in the liver. This hardening of the arteries is known as atherosclerosis. Never use anti-cholesterol drugs to lower the cholesterol level, for this method counter the body natural cholesterol production due to chronic dehydration over time. Correct re hydration daily is the remedy.

Lesions eventually form in the lining of the damaged arteries.
If a blood clot (thrombus) forms at the lesion, the second stage of a heart attack may happen suddenly as the clot blocks the narrowed blood vessel.
Myocardial infarctions are often fatal since a damaged heart may not be able to pump blood. However, if the affected area of the heart is not too large, the patient usually recovers, although with a weaker heart.

Coronary artery thrombosis
When a clot clogs an artery already choked with fatty deposits, blood is prevented from reaching part of the heart. Without oxygen, the tissue begins to die. In turn lead to damaged heart muscle.


The wall of an artery consists of three layers. The innermost layer, the tunica intima (also called tunica interna), is simple squamous epithelium surrounded by a connective tissue basement membrane with elastic fibers. The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer.

Arteries have an outer membrane, a middle layer of muscle, and an inner membrane. In atherosclerosis, cholesterol builds up [this phenomenal is due to over time cellular dehydration, the logical remedy is to rehydrate your body with regular plain water intake: every 90 minute, drink 10 % of your own daily water quota. Daily water quota is calculated by multiplying 32.53 milliliter with your present body weight numbers (in kilogram)] between the inner membrane and the muscle layer, where it hardens and thickens the artery’s wall. A blood clot may form at the site or it may be trapped there as it travels through the bloodstream.

Blood-vessel cross sections

Arteries (blood vessels going away from the heart) and veins (blood vessels returning towards the heart) have three layers, but because artery must contain the pressure of blood pumped from the heart, its walls are thicker and more elastic. The inner layer is fed by the blood within the vessel ; outer layers are served by built-in small blood vessels.

Veins have valves which structurally designed that keeps blood from flowing back to the capillaries.

Three kinds of Capillaries
Capillaries, are the tiniest blood vessels, have walls only one cell thick, made of a tissue called endothelium. Many capillaries are so narrow that blood cells must travel through them in single file.

1.Continuous capillaries, found in muscle tissue, let fluids in and out at the joints between cells in their walls. Found in hands, finger tips.

2.Fenestrated (“windowed”) capillaries are more porous ; found in the kidneys, endocrine glands, and intestines, they permit more fluids to enter and leave the bloodstream.

3.Sinusoids are enlarged capillaries in the bone marrow, spleen, and liver, where their cell-size openings allow blood cells to enter and leave the bloodstream.

How veins keep blood moving
Because the heart’s action is so far away, veins need help in moving blood back toward the heart. Curiously enough, many veins get that help from neighbouring arteries which travels parallel. With each heartbeat, the artery swells, squeezing the parallel veins ; inside the veins, one-way valves open and close to keep blood moving . Hence the direction of the blood flow in arteries is opposite that in the veins.

How do veins and arteries differ?

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