Circulatory System

Introduction: Welcome to Unit Two, Major Topic One! This section is going to begin by exploring the circulatory system. In this section, you will find the different parts of the circular system, functions, and a little mention to the lymphatic system.

Parts:

The main part of the circulatory system is, of course, the heart. The heart is what pumps the blood throughout the system. Some fun facts about the heart-->

*Your heart is about the size of one fist grasped by the other hand.
*"The heart can create enough pressure that it could squirt blood at a distance of thirty feet."
*"The human heart weighs less than a pound."

*(The credibility of these "fun facts" is questionable but may be found at www.funshun.com)*

Found at http://www.coral-lab.org, here is a picture of a real human heart that has been preserved.

The next part of the circulatory system is the blood. The average adult carries about 5 quarts of blood. Luckily, it is created so quickly in the body, that giving blood is safe. I will never forget the first time I gave blood and the only thing I kept thinking was, "Wow...are they going to leave me any?!"

Below is a picture of red blood cells from http://science.uwe.ac.uk
There will be more about blood in the next section.

Last but not least are the blood vessels that travel all throughout the body. Again, more of this will be in the next section.

Here is a nice picture depicting blood vessels from http://www.accessexcellence.org.
Functions:
The circulatory is obviously very important. The book describes different functions of the Cardiovascular System. They are as follows:

1. When the heart pumps, it creates blood pressure, which moves the blood through blood vessels.

2. Blood vessels transport the blood

3. Many exchanges occur at the capillaries, refreshes blood and then tissue fluid.

4. Heart and blood vessels regulate blood flow according to needs of the body.

(Pg. 86)

Personal Assistant:

I am sure many of us would not mind having a personal assistant to do our chores and errands. We do have a personal assistant, but it assists our circulatory system. This is called the lymphatic system. (http://www.nlm.nih.gov)

The lymphatic system is there to collect excess tissue fluid, and then return it to the circulatory system. This is the main purpose. It also absorbs fat and fat-soluable vitamins from the digestive system. Lastly, and probably the most well known, is that the lymphatic system is the defense against invading microorganisms and disease.

Conclusion: We have just taken a very brief look at the circulatory system, its parts, functions, and assistance system. Not it is time to go a little bit more into detail. The next section is dealing with different blood vessels involved in the body. We will look at a few dfinitions, and some of the exchanges that occur at the capillary level.