The Cardiovascular System
It's all about Distribution!

Your cardiovascular system really is all about distribution.  Just how much time do you spend pondering your pump, pipes and valves?  If you're like me and most other people, probably not much.  

Our country's distribution systems (roadways, railroads, pipelines and transmission lines) are the main things that keep the American economy moving and growing.

In comparison, can you imagine a three-phase, electrical pump that weighs less than a pound, is about the size of a closed fist, moves 700,000 gallons of viscous (thick) fluid per year and can move four times that amount if necessary, and only rests a quarter of a second between phases?

Furthermore it moves that fluid through a 50,000 mile network of pipes.

We all have one.  It's our cardiovascular system and our heart is the heart of the matter.  There is no man-made pump or distribution system that can even come close.

C'mon, 50,000 miles of blood vessels?

Just like our country's physical distribution systems keeps the economy strong and growing, so does our cardiovascular system.  The "pipes" are arteries and veins.

Arteries are thick-walled vessels that carry oxygen-rich blood away from the heart and thin-walled "pipes" called veins, that carry oxygen depleted blood to the heart.  This is the systemic circulation of our distribution system.

capillary vessels

Pulmonary circulation is part of the pipeline that carries the oxygen depleted blood via pulmonary arteries, from the heart to the lungs where it picks up a load of fresh oxygen that is returned to the heart through pulmonary veins.

When the word "pulmonary" pops up, think "lungs".

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The "Heart" of the Cardiovascular System!

The master engineer who designed our hearts and cardiovascular system didn't know about KISS.  It is anything but simple.  For starters, consider its construction. 

In one sense, we are "two-hearted", not to be confused with "two-faced".  More accurately, our heart has two sides, a right and left side. 

The "right" heart receives the oxygen depleted blood from the body and moves it to the lungs.  The "left" heart takes the re-oxygenated blood from the lungs and delivers it back to the body.

heart pictorial

To complicate things even more, the difference in the two sides of the heart is not just one of function.  They are Anatomically different. 

Each side operates at different pressures and the left side muscles are four times thicker and thus much more powerful than those on the right side.

Furthermore, each side of the heart has upper and lower chambers.  These chambers have pretty cute names; the upper is the atria which means "waiting room" and is aptly named since this is the chamber that receives blood from the veins and pumps it to the lower chamber. 

The lower chambers are called ventricles which translates to "little belly" in plain English.  The ventricles move the blood to the body and lungs.

The remarkable thing about the heart and cardiovascular system is that it works at all.  Aside from the complexity of its construction,
how does it know when to squeeze or compress, known as systole, and relax, known as diastole?  When our blood pressure is measured; it will be given as two numbers, like the optimum 115/75. 

The larger number is called the systolic pressure, the "squeezing" pressure.  The lower number is the diastolic or resting number.  By the way, when we say "blood Pressure", we are referring to the force that circulating blood exerts on the arterial blood vessels, that is, the large arteries that carry blood away from the heart.

Back to the question, how does it know when to squeeze or relax?  As was alluded to earlier, it is an "electrical" device.  Impulses (electrical signals) emanate from special cells called "pacemaker cells" that
stimulate the heart to contract. 

The electrical impulse starts at the top of the heart and moves down, squeezing blood out of the heart much like we squeeze water out of a chamois when we wash the car and wipe it down.

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Me First!

Before any of the body gets fed, the heart takes care of itself first.  It has to.  The heart must get its share of oxygen and nutrients from the blood before it can do its job efficiently. 

Fortunately, the designer thought to include right and left side coronary arteries in the package.  These supply blood to both sides of the heart in redundant pathways so it does care for itself very well.

Red Alert! Crash Cart! Stat!

In something as complex as the cardiovascular system, there's a lot that can go awry. 

On various occasions, I have had water pumps, hydraulic fluid pumps and fuel pumps in my car quit working.  At best, it was a real inconvenience and at worse, pretty expensive to repair.  When the pump in our chest quits working, it's more than an inconvenience.

Remember those coronary arteries?  If blood flow through them is reduced by 70% or more for just a few minutes, the heart muscle dies and we experience a "heart attack" or "coronary", in doctor speak, it's a myocardial infarction.  If something disrupts the electrical signals that tell the heart when to contract, it can go into a state called fibrillation. 

Instead of having a steady, rhythmic heart beat, it goes into an irregular spasmodic dance that can stop blood circulation to the rest of the body.  Devices such as pacemakers and automatic internal cardiac defibrillators can be put in the patient’s chest to restore the heartbeat to normal.

The heart also has four valves to keep the blood going in the right direction and prevent "backflow".  With the heart, all streets are "one-way".  The valves function is simply to open and shut at the right time and "open" means open, and "shut" means shut...leaving the door ajar is not allowed here.

As an example of valve malfunction, consider the mitral valve, that's the one between the left atrium and left ventricle.  The corresponding valve on the right side is the tricuspid valve. 

Just to complete the roster, the other two valves are the pulmonary valve and the aortic valve.  Both are ventricular valves; pulmonary on the right and connecting to the pulmonary artery; aortic valve on the left connecting to the aorta.
 
Back to the "Mitral Valve".  The mitral is a noted troublemaker and can cause a lot of problems, most often seen in young women.  It is supposed to slam shut and stay tightly closed until the next batch of blood is ready to be passed on.  But very often, it doesn't shut very well and blood seeps by when it shouldn't.

The name for this is "Mitral valve Prolapse" and it causes heart palpitations, sweating and panic attacks.  The good news is that many times the problem is simply outgrown and it takes care of itself (but not always).

Incidentally, the heartbeat that the doctor hears though the stethoscope is sound of those valves slamming shut...
but you already knew that.

Blood:  The river of life...
and the channels that carry it.

"I'm going out for a bite to drink." (George Hamilton as Dracula in Love at First Bite, 1979)' While blood is essential to a vampire; we're lucky, our body makes all we need.

How many of us think of blood as an organ?  If a bodily organ is a system of different kinds of tissues that work together to perform a specific function in the body, then blood is an organ of the cardiovascular system.  If we put a blood sample in the centrifuge and spin it around a bit, we will see that blood is made up of three distinct parts. 

A little less than half (45%) is the red blood cells, or erythrocytes, and this would be the most dense layer and thus be on the bottom.

The lightest layer, seen at the top, is plasma, about 55% of the volume.  It's made up of clotting proteins, antibodies that fight infection, sodium, potassium and chloride electrolytes and water.

blood cell types

The middle layer is the white blood cells, also known as leukocytes, and make up only 1% by volume.

Normal red blood cells

Blood makes up about 8-9% of body weight and, in a large male, is about 1.5 gallons in volume; that would be about twelve pints.  The range is generally between 10 and 12 pints.

It's best not to donate more than one pint of blood every month or so since it takes red blood cells about 36 days to replace themselves although plasma is replaced in two or three days.

Photo: top shows red cell, platelet and white cell from left to right.  right shows cluster of red blood cells.

Blood does a lot of things in our body's cardiovascular system including transporting, protecting and supporting homeostasis (balance).
Among other things it:

    • Delivers oxygen to all the body's tissues
    • Removes carbon dioxide from tissues
    • Absorbs nutrients from the GI tract
    • Removes wastes from cells
    • Carries hormones and chemicals to target organs
    • Stops bleeding; fights infection
    • Maintains equilibrium in the body (Homeostasis)
    • Maintains pH equilibrium between 7.1 and 7.4
    • Regulates temperature
    • Regulates fluid and electrolyte balance

Winston Churchill said "I have nothing to offer but blood, toil, tears and sweat.”  Winston can offer up his blood but I think I'll try to hang onto mine as long as I can.

The Heart Moves It...
Arteries and Veins Transport It.

So let's take a look at the pipelines...
and what can go wrong.

As a start, a quick overview of the network of blood vessels in our cardiovascular system is in order.  It won't be in depth since this isn't intended to be an anatomy or physiology course. 

What we are moving toward is an understanding of how to take care of this network of vessels so we can keep climbing stairs, running, walking and exercising without collapsing.

Every blood vessel belongs to either the right or left side of the vascular system.  The arterial left side is the high pressure system that takes oxygen rich blood and nutrients to the body.  The venous right side is the low pressure system that brings depleted blood back to the heart from the lungs.
 
Speaking of lungs, remember "pulmonary", means "pertaining to the lungs".  Pulmonary arteries carry oxygen depleted blood from the heart to the lungs and pulmonary veins move oxygen rich blood from the lungs to the heart.

As might be expected, arterial vessels (going away from the heart) decrease in size going from the heart to the rest of the body: large arteries, medium arteries, small arteries, arterioles and capillaries. 

The capillaries comprise most of the 50,000 miles of blood vessels and the inside diameter is a little larger than one red blood cell.
 
By the way, the inside of a blood vessel, where the blood flows, is called the "lumen".

Conversely, veins (returning to the heart) increase in size as they get closer to the heart; just the opposite of the arteries.

As to structure of the vessels, we will focus on the cardiovascular systems arteries (high pressure vessels).  They have three layers;
the innermost layer in contact with the blood is the intima and it is very smooth and slippery so blood can flow nice and unobstructed.

The middle layer is the media (makes sense) which is muscular in nature so it can support the structure of the vessel.  It is the muscular structure that lets the vessel expand or contract in response to various stimuli; like exercise or stress or anxiety. 

The outer layer is the adventitia.  It's the sausage skin or the cellophane wrap that holds the vessel together.

Ok, enough of the anatomy lesson.  Let's look at what goes wrong in our blood vessels.

As might be expected, heart disease starts at that innermost layer of the blood vessel, the intima.  Normally, this layer is lined with a layer of cells that are perfectly smooth but they are delicate. 

Numerous things can damage this smooth layer; high blood pressure, high blood sugar, toxins from nicotine or other inhalants and homocysteine, an amino acid by-product from the digestion of protein. 

Homocysteine is crystalline in shape and excessive levels, with their sharp crystalline corners, could cause damage to the vessel wall; that's the theory anyway.

When the smooth layer of cells is damaged, a gap or nick is formed. In an effort to protect the blood vessel, the body "plasters" over the nick with cholesterol. 

If the cholesterol used to patch the nick is LDL, low-density cholesterol, it causes an inflammatory reaction.  The inflammation causes while blood cells to rush to the scene, irritating the plaque and causing a blood clot to form.
 
If the clot is large enough, it will decrease blood flow through the artery and in extreme cases, close it down completely.  Whatever muscle or tissue was receiving oxygen and nutrients from that artery then begins to die.  In the extreme, the result is a heart attack or stroke.

Photo: below shows atherosclerosis, classic plaque buildup with narrowing of the artery; likely started with a nick to the intima, the inner artery wall.

Plaque in arteries

Seems like it might be a good idea to take special care of our pipes.  Let's see how to do that.

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Cardiovascular System Health...
Keeping it Primed!

The heart is a muscle,
don't be afraid to exercise it.

Exercise is important to the cardiovascular system because it lowers the blood pressure, both systolic and diastolic.  High blood pressure is the key factor in arterial aging. 

Two good reasons to exercise are that any amount lowers bad LDL cholesterol and raises the good HDL cholesterol.  Since the heart is a muscle, exercise strengthens it and forces the vessels to dilate and remain more flexible.

Data shows that for maximum cardiovascular system benefit, we should put it through stamina training in 20 minute intervals three times a week. 

Stamina training is any cardiovascular activity that raises the heart rate to 80% or more of your age adjusted maximum for an  extended period of time.  The formula is 80% of 220 minus your age.

If someone is 55 years old that is 220 - 55 = 165 times .80 = 132.  The ideal way to do this is with a treadmill or recumbinant bicycle that has pulse sensors.

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The Cardiovascular System
doesn't Run on Junk!

One way we can help the heart maximize its nutrition is to make sure we are feeding ourselves properly for good cardiovascular system health.  Changes in the diet to maximize cardiovascular system health is simple.

First is to start eating about a handful of nuts everyday if you aren't already doing so.  Walnuts are one of the best but all of them are good sources of protein, omega-3 essential fatty acids and antioxidant flavonoids.

If you use vegetable cooking oils, switch to extra virgin cold-pressed olive oil.  The monosaturated fats (essential fatty acids) in olive oil raise good HDL cholesterol, cleaning out the arteries in the process.

Eat more fish, the cardiovascular system likes fish; about three serving a week.  Focus on fatty fish like salmon, cod, bass and whitefish since all are rich in omega-3 fatty acids.  If you have read about mercury build up on ocean fish you may want to specify wild line-caught salmon when you buy it (unless you are lucky enough to be able to catch it yourself). 

Other fish having the least chance of having mercury or PCBs are mahi mahi, catfish, flounder and tilapia; just be sure none of them come from China.  You don't want to know how factory farmed fish are fed in China.

If you decide to go ahead and increase your fish consumption it would be a good idea to supplement with an top of the line antioxidant and one of the supplements that help clear heavy metals from the body.

Get a fix on the natural antioxidants as well, the flavonoids.  The cardiovascular system would appreciate about 31 milligrams a day from green tea, grapes, blueberries, nuts, tomatoes and tomato juice, 100 percent natural orange juice (Lots of pulp is best), and just about any of the colorful berries.

Know what foods the cardiovascular system doesn't like.  Avoid all trans fats and limit the saturated fats; no more than 20 grams a day combined.  Mostly these come from highly marbled meat, full-fat dairy products, commercially baked goods, fast food and palm and coconut oils.  That said, virgin coconut oil is really good for brain health among other things, just go easy on it. 

On the sweet front, avoid simple sugar, high fructose corn syrup (this is hard to do), most white processed food; especially white mashed or baked potatoes, white bread and white rice.

All this stuff tends to damage the blood vessel cell wall, causing nicks that lead to inflammation and thus plaque build up.  The high glycemic white foods and sugars can contribute to obesity leading to insulin resistance and possibly ending in diabetes; very damaging to the cardiovascular system, especially the arteries.

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Dietary supplements:
Mandatory for good
cardiovascular system health!

Many doctors are now recommending a half aspirin a day for anyone over 40 (35 for men).  That's about 162 milligrams a day.  The benefit is that it makes blood platelets less sticky and reduces inflammation in
the entire cardiovascular system. 

The downside is that what's good for the cardiovascular system, may be bad for the stomach lining and could make ulcers worse.

Look for a good multivitamin containing at least 400mg of Magnesium; it supports a stable heart rhythm.  Add to that, 600mg of Calcium (twice a day for 1200 mg total). Combined with the magnesium, it helps lower blood pressure.

Be sure the multivitamin has 400 to 600 IU of vitamin D to help with the calcium absorption and decrease inflammation in the vessels.

Include 600 mg of vitamin C twice a day; 400mg of vitamin E (to provide antioxidant protection) and potassium for arterial health (you can get this from four fruits per day and avoid the supplement).

The cardiovascular system loves Folate.  It loves 800mmg (micrograms) of Folate per day, also known as folic acid or vitamin B9. Folate has been shown to lower homocysteine levels; vitamins B6 and B12 should be included as well.  If Folate sounds a bit like foliage it's because the name comes from the Latin word for "leaf".

If you are taking a statin drug like Lipitor, Crestor or Zocor to lower cholesterol check with your doctor before bulking up on the vitamin C and E as they inhibit the anti-inflammatory effects of the statins although they don't affect the cholesterol-lowering benefit of the statins. 

Note that use of statins have been linked to cognitive impairments which we will look at in the section on strokes.

Get enough sleep.

The optimum amount of sleep for the cardivascular system is seven to eight hours a night for men and six to seven hours for women.  Sleep is very therapeutic for the arteries and not enough increases the risk for heart attacks and ages the arteries. 

The thing about sleep is that it has to be "good" sleep meaning that it takes about two and a half hours into the sleep before it starts to become restorative.  For more on the physiology of sleep, click on the "Lifestyle Choices" on SLEEP.

The Cardiovascular System Dashboard

Blood pressure matters...
and the optimum is 115/75.

Excessive blood pressure (hypertension) damages the inner walls of blood vessels leading to plaque buildup and clots.  Blood pressure responds to lifestyle changes in diet, exercise and sleep and if that isn't enough, there's always the drugs. 

If you go the drug route, your cardiovascular system asks that you check closely for side effects and interactions. 

The recommendation is for everyone to have their blood pressure checked regularly and get it corrected if it starts running high.  High means over 140/90 for adults but be aware the blood pressure readings are highly variable depending on mood, activity, time of day, surroundings and other external stimuli. 

So if possible, it is best to take readings periodically in the morning, noon and evening.

Cholesterol levels:
Once a year check-up.

This does mean drawing blood and having a lab test done but
while you’re at it there are three other readings that can be done at the same time.  All of them are important to the cardiovascular system.

A cholesterol reading should give the total cholesterol, the "bad" LDL cholesterol and the "good" HDL cholesterol.  Guidelines for each are:

cholesterol pictorial

To keep the LDL and HDL straight, just think of the "L" as low and lousy; and the "H" as high and healthy.

Photo:  Representation of cholesterol in blood stream, from
NIH Medline website

What about Homocysteine?

It should also be checked and the ideal is 9 mg/dl.  Recall that homocysteine is an amino acid produced as a by-product of protein digestion and causes nicks in the cell walls.

C - reactive protein (HsCRP):
Another Once a year Check-up

The "Hs" stands for "high sensitivity".  HsCRP is a marker
for inflammation in the body from any source whether it be a gum infection, urinary tract infection, appendicitis or any of the "itis" conditions.  If you see "itis" on the end of a word, it means inflammation.

High inflammation in the body means high inflammation in the blood which means increased risk for inflammation in the blood vessels; the whole cardiovascular system for that matter.

HsCRP readings are:

  • Low risk = 1 mg/liter or less
  • High risk = 3 mg/liter or more
  • C-reactive protein levels can be lowered by first eliminating the infection if there is one; exercise, take a baby aspirin or half a regular aspirin a day (except don't take aspirin and a non-steroidal anti-inflammatory such as Ibuprofen together in a 24-hour period), supplement with Niacin, and maintain good dental hygiene to name a few.

    Blood sugar:
    Watch it and keep it lower than 100 mg/dl.

    You can do this one yourself if you get a meter, test strips and a finger sticker at the drug store.  It all usually comes prepackaged in a kit.  Excess blood sugar, especially that caused by diabetes, damages the arteries. 

    It does this by deactivating a substance that allows the arteries to dilate and contract easily.  If the vessels can't do that, cracks form in the vessel walls and the cardiovascular system wouldn't be happy.  It invites the formation of plaque and clotting.

    Emotion and Mental State Matters

    Lastly there is an emotional side to good cardiovascular system health that includes anger management, avoiding hostility, keeping depression at bay and controlling stress.

    Strong negative emotional states can rob you of as much as eight years of life.  The mechanism is high blood pressure caused by these strong emotions.

    Depression is nothing to take lightly.  A feeling of helplessness weakens the immune system and people suffering from chronic depression are four times more likely to experience heart attacks than those who are not depressed.

    Stress is a killer

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    It is the single greatest cause of premature aging.  There is a complex physiology at work with chronic stress that goes back to the "flight or fight" reaction that was programmed into us when we were fighting
    saber-tooth tigers.

    In a life threatening situation where we must quickly decide to stand and fight or run like crazy, the stress reaction is a good thing that pumps adrenalin into our system. 

    Once the situation is resolved and we settle down, the excess adrenalin, cortisol and other powerful stress chemicals are sent to the liver for elimination.  It was meant to be a temporary thing. 

    But in today’s world we are more than likely under constant stress and those chemicals stay in our system and never get completely eliminated.  The result is inflammation, damaged arteries, plaque buildup, clotting and stroke or heart attack.  The message is that we need to learn how to chill.

    Moving Forward

    Before wrapping up this page, here is another good reference from the Texas Heart Institute for the heart and its supporting cast. It has some good interactive models showing how it all works.

    In conclusion, from here you may leave the cardiovascular system and return to the Healthy By Nature Home Page or continue on to one of the other anatomical systems discussed via the links below.


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