Cardiovascular System

Cardiovascular System

Blood Vessels
User's Manual
Amazing Facts
Related Links


"Blood is thicker than water," it also exists within a fraction of an inch from every cell of your body. Its composition is always changing, as it travels from one organ or tissue to the next, responding to external and internal stimuli. It constantly circulates in order to supply every cell with oxygen, water and other nutrients, and to dispose of wastes and toxins, in order to keep you alive. Failure to do so for over 3 minutes can result in death.

Blood Vessels

supply the road map through which blood travels. The heart is the single motor for all traffic along your circulatory system. Arteries carry the blood away from the heart, branching into smaller and smaller tributaries called arterioles like a river in reverse. Every artery is surrounded by smooth muscle that can relax to increase flow or constrict to reduce flow. Your autonomic nervous system controls these muscles like a giant traffic light switchboard, directing the most amount of flow to the areas that need it most at any given time.

If you take off into a sprint, the arteries supplying your leg muscles will relax and expand allowing more blood to bring needed oxygen and nutrients to the leg's muscles. Eat a burger, and the arteries supplying your digestive tract relax increasing blood flow and absorption of digestive nutrients. Spend too much time in the hot sun and the arteries supplying your skin relax allowing blood more of a chance to release heat near the body's surface.

Eventually the blood traveling through the arterioles branches into the smallest type of blood vessels known as capillaries. In fact capillaries are so small that often red blood cells are forced to travel through them in a single file line. One arteriole could serve 100 capillaries. The walls of capillaries are only one-cell thick, and it is through these walls that nutrients and waste are transferred between the blood and the tissue. The capillaries eventually converge forming small tributaries called venules. These converge to form small veins, which continue to join forming larger and larger veins. All these veins eventually drain into the heart. Veins have thin walls devoid of muscle. By the time blood reaches the veins it has lost much of the pressure put on the blood within the arteries. The veins contain valves, which prevent blood from flowing backward. The heart moves the blood through the veins by repetitively sucking some of it into one of its chambers, transferring that blood to a different chamber and pushing it out through an artery.

User's Manual

A healthy diet
A well-rounded meal roughly composed of 60% carbos, 10-15% protein, 25-30% fat. You can disregard the numbers as long as you center your meals around fruits veggies and grains (including pasta) and keep your meat poultry and seafood intake between 4-6 ounces per day. (about the size of your fist)

Avoid add on fats like butter and oil.
This avoids cholesterol sludge in your arteries and keeps weight and blood pressure down.

Avoid saturated fats.
Eat unsaturated fats unless there is a family history of cancer.

Avoid fatty greasy foods.

Avoid eating large quantities of salt.

Cook from scratch.

Eat carrots and other yellow and orange veggies.
These are rich in antioxidants, including Vitamin C and Beta-carotene, to protect against heart disease.

Aerobic exercise
Aerobic exercise such as running, swimming, biking or hiking, 30 minutes a day 3 times a week. Lack of exercise can be as great a risk factor as smoking, high blood pressure and high cholesterol.

Get 8 hours of sleep every night.

Don't Smoke.

Keep your weight at a healthy level.
Refer to the body weight


Exercise can help you accomplish this.

Visit your doctor for a physical every year.
They'll make sure your weight is normal, your blood pressure is under 140/90 and your total cholesterol divided by your HDL is 4.5 or below. (LDL is the cholesterol that deposits fatty plaque on your arterial

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Amazing Facts

At any one time...

  • the arteries contain about 20% of the blood
  • the capillaries contain only 5% of the blood
  • and the veins contain about 75% of the blood

The heart pumps 5 liters of blood through the body
The heart beats over 100,000 times a day.
The heart pumps up to 2.5 billion times in an average lifetime
The heart is about the size of your fist
An average heart rate for men is 70-72 beats per minute
An average heart rate for women is 78-82 beats per minute

Related Links

Your Heart

Your lymphatic system, the other part of circulation