Heart Disease and High Choleseterol

The normal human heart is a strong, muscular pump a little larger than a fist. Each day an average heart “beats” (expands and contracts) 100,000 times and pumps about 2,000 gallons of blood.
In a 70-year lifetime, an average human heart beats more than 2.5 billion times.

The heart pumps blood continuously through the circulatory system. The circulatory system is the network of elastic tubes that carries blood throughout the body. It includes the heart, lungs, arteries,
arterioles (small arteries) and capillaries (very tiny blood vessels). These blood vessels carry oxygen- and nutrient-rich blood to all parts of the body. The circulatory system also includes venules (small veins) and veins. These are the blood vessels that carry oxygen- and nutrient depleted blood back to the heart and lungs. If all these vessels were laid end-to-end, they’d extend for about 60,000 miles. That’s enough to encircle the earth more than twice.
The circulating blood brings oxygen and nutrients to all the body’s organs and tissues, including the heart itself. It also picks up waste products from the body’s cells. These waste products are removed as they’re filtered through the kidneys, liver and lungs.

What is the Hearts Structure?

The heart has four chambers through which blood is pumped. The upper two are the right and left atria. The lower two are the right and left ventricles. Four valves open and close to let blood flow in only one direction when the heart beats:
1) The tricuspid valve is between the right
atrium and right ventricle.
2) The pulmonary or pulmonic valve is
between the right ventricle and the
pulmonary artery.
3) The mitral valve is between the left
atrium and left ventricle.
4) The aortic valve is between the left
ventricle and the aorta.

Each valve has a set of flaps (also called leaflets or cusps). The mitral valve has two flaps. The others have three. Under normal conditions, the valves let blood flow in just one direction. Blood flow occurs only when there’s a difference in pressure across the
valves that causes them to open.

How Does The Heart Pump Blood?

The heart pumps blood by a highly organized sequence of contractions of its four chambers. The heart works as follows:
The right atrium receives blood from the veins. This blood carries little oxygen and lots of carbon dioxide. That’s because it’s returning from the body’s tissues, where much of the oxygen was removed and the carbon dioxide added. Venous blood is darker than arterial blood because of the difference in dissolved gases.
While the heart is relaxed, venous blood flows through the open tricuspid valve to fill the right ventricle. An electrical signal starts the heartbeat by causing the atria to contract.
This contraction “tops off” the filling of the ventricle. Shortly after the atrium contracts, the right ventricle contracts. As this occurs, the tricuspid valve closes and the partially de-oxygenated blood is pumped through the pulmonary valve, into the pulmonary artery and on to the lungs. In the lungs the blood gives up its carbon dioxide and gets oxygen before returning to the left atrium. This newly oxygenated blood is bright red.

At the same time the right atrium contracts, the left atrium contracts, topping off the flow of oxygenated blood through the mitral valve and into the left ventricle. Then a split second later the left ventricle contracts, pumping the blood through the aortic valve, into the aorta and on to the body’s tissues.

A heart’s four chambers must beat in an organized way. This is governed by the electrical impulse. A chamber of the heart contracts when an electrical impulse moves across it. Such a signal starts in a small bundle of highly specialized cells in the right atrium — the sinoatrial node (SA node), also called the sinus node. A discharge from this natural “pacemaker” causes the heart to beat. This pacemaker generates electrical impulses at a given rate, but emotional reactions and hormonal factors can affect its rate of discharge. This lets the heart rate respond to varying demands.

The electrical impulses generated by the SA node move throughout the right and left atrium, causing the muscle cells to contract. Shortly after both atria have contracted, the electrical signal travels down specialized fibers throughout the ventricles. The signal’s path causes the ventricles to contract together in a wringing motion, squeezing blood from them. The route of this electrical impulse is specific and produces the coordinated, sequential contraction of the
heart’s four chambers that’s necessary for the heart to work properly.

Atherosclerosis: A Major Cause of Cardiovascular Disease

Atherosclerosis comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness). It involves deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances in the inner lining of an artery. This buildup is called plaque. It usually affects large and medium-sized arteries.

Atherosclerosis is a slow, complex disease that starts in childhood and often progresses when people grow older. In some people it progresses rapidly, even in their third decade. Many scientists think it begins with damage to the innermost layer of the artery. This layer is called the endothelium.

Three proven causes of damage to the arterial wall are
1) elevated levels of cholesterol and triglyceride in the blood,
2) high blood pressure and 3) tobacco smoke.
Tobacco smoke greatly worsens atherosclerosis and speeds its growth in the coronary arteries, the aorta and arteries in the legs. (The coronary arteries bring blood to the heart muscle; the aorta is the large vessel through which the heart pumps blood that goes to the body.)
Because of the damage to the endothelium, fats, cholesterol, platelets, cellular debris, calcium and other substances are deposited in the artery wall. These may stimulate artery wall cells to produce other substances that result in further buildup of cells. These cells and the surrounding material (plaques) may become large enough to thicken the endothelium significantly. The artery’s diameter shrinks and blood flow decreases, reducing the oxygen supply.
Plaques can also become unstable and rupture. Those that rupture cause a blood clot (thrombus) to form that can totally block blood flow in the artery. A blood clot that breaks off and travels to another part of the body is called an embolus. If a clot blocks a blood vessel that feeds the heart, it causes a heart attack. If it blocks a blood vessel that feeds the brain, it causes a stroke. And if blood supply to the arms or legs is reduced, it can cause difficulty walking and eventually gangrene.

What is Cholesterol and where does it come from?

Cholesterol is a soft, fat-like substance. It’s found in the blood and in all the body’s cells. It’s an important part of a healthy
body because it’s used to form cell membranes, some hormones and other needed tissues.
People get cholesterol in two ways. The body — mainly the liver — produces varying amounts, usually about 1,000 mg a day.
Another 400 to 500 mg (or more) can come directly from foods. Foods from animals (especially egg yolks, meat, fish, poultry and whole-milk dairy products) contain it; foods from plants don’t. Typically the body makes all the cholesterol it needs, so people don’t need to consume it.

A high level of cholesterol in the blood is a major risk factor for coronary heart disease, heart attack and stroke. Hypercholesterolemia is the term for high levels of blood cholesterol.
Cholesterol and other fats can’t dissolve in blood. They have to be transported to and from the cells by special “carriers” called lipoproteins, which are created by the liver. Lipoproteins carry cholesterol and triglycerides, which are found in foods and made by the body.
The process starts when cholesterol and fats in food go to the intestine to be digested and absorbed. Chylomicrons are made in the intestinal wall. Chylomicrons are fatty particles containing mainly triglycerides, but also cholesterol, phospholipids and protein.
When the chylomicrons enter the bloodstream, they contact with binding sites on capillaries. Many of their triglycerides break down and are released into the blood. The rest of the chylomicron (the “chylomicron remnant”), now richer in cholesterol, continues in circulation until it reaches the liver and is absorbed.

The liver then produces very-low-density lipoprotein (VLDL), the largest type of lipoprotein. VLDL carries triglycerides made in the liver from fatty acids, carbohydrates, alcohol and some cholesterol. VLDL is released into the bloodstream and, like chylomicrons, is carried to tissue capillaries. There the triglycerides are broken down and either used for energy or stored by muscle or fat cells.

After VLDL releases its triglycerides, what remains is a “VLDL remnant” called intermediate-density lipoprotein (IDL). Some IDL is removed from circulation by the liver; the rest is transformed into low-density lipoprotein (LDL).

What is LDL Cholesterol and why is it the dangerous one?

LDL is the major cholesterol carrier in the blood. It carries about 60 to 80 percent of the body’s cholesterol. Some of this cholesterol is used by tissues to build cells, and some is returned to the liver. If too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries feeding the heart and brain.
Together with other substances it can form plaque and contribute to atherosclerosis. That’s why LDL cholesterol is often called “bad” cholesterol. Lower levels of LDL cholesterol reflect a lower risk of heart disease. A high level of LDL cholesterol (160 mg/dL and above) reflects an increased risk of heart disease. An optimal level of LDL cholesterol is less than 120 mg/dL, especially for people who have
coronary heart disease or diabetes.

What is HDL Cholesterol and why is it the good one?

About one-third to one-fourth of blood cholesterol is carried by high-density lipoprotein or HDL. It is a flat, disk-like particle produced primarily in the liver and intestines and released into the bloodstream.
As VLDL and chylomicron particles release their triglycerides into the body’s cells, fragments containing proteins, fats
and cholesterol break away. Medical experts think HDL tends to carry cholesterol away from the arteries and back to the liver, where it’s passed from the body.

Some experts believe HDL removes excess cholesterol from atherosclerotic plaques and thus slows their growth. Recent studies indicate that the antioxidant and anti-inflammatory properties of HDL also inhibit atherosclerosis. HDL cholesterol is “good” cholesterol because a high level of it seems to protect against heart attack. The opposite is also true: People with a low HDL cholesterol level (less than 40 mg/dL) have a higher risk. A low level of HDL cholesterol also may raise stroke risk.

As a rule, women have higher HDL cholesterol levels than men. The female sex hormone estrogen tends to raise HDL cholesterol, which may help explain why premenopausal women are usually protected
from developing heart disease. Estrogen production is highest during the childbearing years.
Triglyceride levels range from about 50 to 250 mg/dL, depending on age and sex. As people tend to get older, fatter or both, their triglyceride and cholesterol levels tend to rise. Women also tend to have higher triglyceride levels. Many people who have heart disease or diabetes have high triglyceride levels, called hypertriglyceridemia.
A high triglyceride level combined with low HDL cholesterol or high LDL cholesterol seems to speed up atherosclerosis. The American Heart Association recommends keeping fasting triglyceride levels below 150 mg/dL.

So the key to good heart health is keeping your HDL Cholesterol high and The LDL Cholesterol Low. It is easy to remember H for high and L for low. I also remember the L in LDL as Lousy, this reinforces in your memory that LDL is bad for you.

How do you maintain proper levels?

Eating fish rich in Omega 3 fatty acids is a good start, limiting your Red Meat intake to once every 2 weeks is also helpful. If you do not eat fish purchase a Omega 3 Fish Oil supplement that is high in EPS and DHA, those are the two constituents that raises your HDL levels.
Following a Mediterranean diet has shown in quite a few studies to keep your HDL high and LDL low. Do some research on this diet and try to incorporate some of its strategies into your current lifestyle.