Blood Vessels

Q:  What are the differences between veins, arteries, and capillaries?  What are varicose veins and what are the causes?

A:  The cardiovascular system consists of the heart, blood vessels, and blood.  The blood vessels transport oxygen, nutrients, hormones, and cellular waste products throughout the body.  The three main blood vessels are arteries, veins, and capillaries.  The chart below details the primary differences between these vessels.

Arteries

-Carries oxygenated blood 

away from the heart

-No valves

-High pressure

-Thick walls and muscle fiber

to withstand pressure

Veins

-Carries de-oxygenated blood

to the heart

-Valves

-Low pressure

-Thin walls and muscle fiber

due to low pressure

Capillaries

-Fed from arteries

-Smallest and thinnest vessel

-Most common vessel

-Supplies oxygenated blood to tissues 

of the body

Varicose veins are twisted, enlarged veins that form near the surface of the skin and are most common in the lower extremities.  As noted above, veins have valves to ensure de-oxygenated blood flows away from the tissue and back to the heart.

Varicose veins form for various reasons but the most common causes are due to vein valve deterioration, vein muscle weakening due to age, and pregnancy.  Instead of flowing back to your heart, the blood starts to pool in your veins which causes them to become enlarged. The veins appear blue because of the de-oxygenated blood.

The following websites were used as references in answering the question:

http://thecardiovascularsystem.wikispaces.com/Differences+between+Arteries,+Capillaries+and+Veins

http://www.innerbody.com/image/cardov.html

http://www.mayoclinic.org/diseases-conditions/varicose-veins/basics/causes/con-20043474

Sunscreen Application

Q:

With summer upon us, I have started to apply sunscreen.  What does the SPF rating mean (e.g. SPF 30)?

A:

Not only are we well into summer, but May was also Skin Cancer Awareness Month.  So, it is a great time to understand the sunscreen ratings.

SPF stands for Sun Protection Factor.  It refers to the theoretical amount of time one can be in the sun without getting sunburn.  The number that follows the SPF acronym indicates how much longer one can stay in the sun without getting sunburn.

If you normally start to get sunburn in 10 minutes, applying a sunscreen of SPF 30 would allow you to stay in the sun 30 times longer or a total of 300 minutes (10 minutes x 30 = 300 minutes or five hours).

However, SPF is a theoretical amount of time.  If you are outside working, exercising, or just sweating, the actual amount of time the sunscreen will block the sun is much less.  For this reason, it is recommended that sunscreen be applied every two hours.

Which SPF is best (15, 30, 50, or 100)?  The American Academy of Dermatology recommends choosing a sunscreen with SPF of at least 30.  The higher the SPF the more sunrays that are blocked and the longer you can stay in the sun.  However, due to theoretical versus actual time discrepancy and the fact that higher SPF has more chemicals, some dermatologists recommend a SPF of 30 or 50 with liberal application every two hours.

The final sunscreen advice to keep in mind:  No SPF sunscreen can replace the sun blocking ability of sun protecting clothing, umbrellas, or shelters.

The following website was used in answering the question:

http://www.onemedical.com/blog/live-well/spring-has-sprung-the-best-spf-protection-plan-for-rain-or-shine/