Today’s A – Z Challenge post is brought to you by the letter “V”

A to Z Challenge

I am so excited to take part in this, my second, A – Z Challenge!  Last year I did the challenge using “recipes” as my inspiration.  Well, this year I’m going to draw on my nursing background and use “parts of the human body” as my inspiration!  Hmmm…a part of the body that starts with “Q”, “X” or “Z”….

It should be a lot of fun and I’m looking forward to seeing how everyone interprets the Challenge!

So, without further ado,  “V”  is for Vein:

There are two notable exceptions, but generally speaking, veins are blood vessels that carry deoxygenated blood towards the heart.

The two exceptions are the pulmonary veins, which carry oxygenated blood from the lungs to the left atrium of the heart and the umbilical veins, that carry oxygenated blood from the placenta to the fetus.

A - Z Challenge

Image is from Biology,

Veins can be categorized into five main types:

  1. Pulmonary – {described above}
  2. Systemic – these veins return deoxygenated blood from the rest of the body to the right atrium of the heart.
  3. Superficial – veins located close to the surface of the skin and not located near a corresponding artery.
  4. Deep veins – are located deep within muscle tissue and are typically located near a corresponding artery with the same name (for example, coronary arteries and coronary veins).
  5. Communicating veins – (or perforator veins) are veins that directly connect superficial veins to deep veins.
  • A vein can range in size from 1 millimetre to 1-1.5 centimeters in diameter.
  • The walls of veins have three layers of tissues like the arteries but veins are much thinner and less elastic than arteries.
  • Veins have valves that help in the process of returning blood to the heart by preventing the back flow of blood.
  • Veins collapse when their lumens are not filled with blood.
  • Veins appear blue because subcutaneous fat absorbs low-frequency light, permitting only the highly energetic blue wavelengths to penetrate through to the dark vein and reflect back to the viewer.
  • The smallest veins in the body are called venules. They receive blood from the arteries via the arterioles and capillaries.

Just in case you’ve ever wondered; in humans, our blood flows through our arteries and veins in this cycle:

{Key: red is oxygenated blood and blue is deoxygenated blood}

{Oxygenated blood flows from} the Lungs via the Pulmonary Veins (there are 4)
 Left Atrium{Heart}
Left Ventricle{Heart}
Capillaries {exchange of oxygen & co2 }
Superior & Inferior Vena Cava
→Right Atrium{Heart}
Right Ventricle{Heart}
Pulmonary Arteries
Back to the Lungs {where the cycle repeats}

V is also for:

vagina  A tubular organ leading from the uterus to the vestibule of the female reproductive tract that receives the male penis during coitus.

vena cava  One of two large vessels that return deoxygenated blood to the right atrium of the heart.

ventilation  Breathing; the process of moving air into and out of the lungs.

ventricle  A cavity within an organ; especially those cavities in the brain that contain cerebrospinal fluid and those in the heart that contain blood to be pumped from the heart.

venule  A small vessel that carries venous blood from capillaries to a vein.

viscera The organs within the abdominal or thoracic cavities.

I found the above definitions at the McGraw-Hill Applied Biology Resource Center.  Visit their site and you’ll be amazed to know there are even more “V” parts of the body listed there!

The information contained in this post was obtained from WiseGEEK, Wikipedia,, The Franklin Institute and McGraw-Hill Applied Biology Resource Center.


  1. What a great and clear description of the circulatory system. The different colors of ink really helps understand which do what, too.
    Thanks for the great V post.
    Kathy at Oak Lawn Images

  2. First of all – loved the ole school education. Though even now I cannot get Sesame Street out of my head. They always mention brought to you by. Silly I know.

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