20 April 2006

Your arteries

The arterial system is often compared to a road network or river: a large highway or channel dividing to ever smaller byways or tributaries that service every cell.

The arterial system is often compared to a road network or river: a large highway or channel dividing to ever smaller byways or tributaries that service every cell.

What are arteries?
Arteries (with one notable exception) are the blood vessels that carry oxygen-rich blood away from the chambers of the heart to the body’s tissues. The exception is the pulmonary artery, which carries blood to the lungs from the heart. In the lungs, it gets charged with oxygen, then sent back to the heart which pumps it out to body.

The main arterial channel is the aorta, which receives freshly oxygenated blood from the heart, and then divides into smaller arteries that service all the body’s tissues. Finally, the channels are so small (less than 0.3mm) that the blood cells can only pass through them one at a time.

Arteries are structurally quite different to veins, which carry de-oxygenated blood back to the heart from the cells. The walls of arteries are thick and muscular, and can contract to keep the blood moving away from the heart and through the body.

Infamous arteries: the coronaries
Of all the arteries, those that get the most press are the coronary arteries. They branch off early on from the aorta, to supply the heart itself with oxygen-rich blood. A blockage anywhere in the circulatory system can potentially spell trouble, but in a coronary artery it means that blood flow to the heart muscle is compromised. If the blood flow is cut off completely, then the part of the heart muscle it supplies can die – in other words, a heart attack.

Like a sandbank slowly forming in a river, a blockage is most likely to develop where the channel is rough. As kids we have beautifully smooth, flexible arteries, but with age and modern living the arterial lining starts to get damaged. Wherever these rough spots develop, fatty deposits are more likely to collect and blood clots are more likely to form.

Coronary artery disease is the number one killer in the western world, and second only to HIV/AIDS in South Africa. Men are at risk about a decade younger than women are. The good news is that there’s a lot you can do to help prevent it, and you already know how:

  • Eat a variety of foods in moderation, including loads of fresh fruit, veg and whole grains. Avoid most animal fats.
  • Don’t smoke. Within five to 10 years of stopping, ex-smokers’ risk of heart disease equals that of non-smokers.
  • Maintain your ideal body weight. Extra fat, especially round the waist, strains your heart and arteries.
  • Choose an aerobic activity (i.e. one that increases your heart rate), and practise it for at least 30 - 45 minutes at least four times a week. Moderate resistance training can also improve cardiovascular function and reduce the load on your heart.
  • Take time out for relaxation, get enough sleep, and ‘don’t sweat the small stuff’. Practise responding to stressful situations as calmly and objectively as possible. If problems become overwhelming, seek a therapist’s help.
  • Know your stats. Following a healthy lifestyle helps protect you against heart disease. But that may not be enough; however healthy, every man should have regular checkups and know his blood pressure, blood sugar and cholesterol readings.

    Did you know?

    • Laid end-to-end, your blood vessels, from the aorta to the tiniest capillary, would go around the world nearly four times.
    • Premenopausal women are much less likely than men of the same age to have atherosclerosis, but after menopause women's risk increases to equal or even exceed that of men.
    • Moderate alcohol consumption (an average two drinks a day for men), may protect against heart disease.


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