How Do Your Arteries and Veins Work?

Now that we understand that red blood cells carry oxygen and get rid of carbon dioxide, and the rest of your blood is white blood cells that fight infection and platelets that help our blood to clot and plasma that is the liquid that these cells travel around in. How do they actually get to where they need to go?

 

Here enters your vascular system. This system is made up of arteries and veins and teeny tiny vessels called capillaries. When your red blood cells are full of that wonderful oxygen ready to be taken to the body’s cells, they travel through your arteries. Any vessel that travels away from your heart is considered an artery. These vessels are under a high amount of pressure and have muscular walls that allow them to expand and contract as your body needs them to. Did you just eat a big meal? Your gastrointestinal system needs a higher amount of blood flow to help digest and absorb all of those nutrients. Did you just jump up from where you were laying down on the floor? It’s a good thing your blood vessels are able to contract to control your blood flow that way all of your blood doesn’t just pool in your legs!

 

Once the blood in your arteries has reached its intended organ it enters tiny vessels that are called capillaries. Capillaries have very thin walls that allow for an exchange to occur between your cells. For instance your red blood cell is able to hand the oxygen molecules that it has been carrying over to your body’s cells and in exchange the cell can hand over the carbon dioxide waste product that it needs to get rid of.

 

Once the blood has passed through the capillaries it is now carrying carbon dioxide instead of oxygen. This means that it needs to travel back to your lungs in order to get rid of the carbon dioxide and replace it with fresh oxygen to take back out to the cells all over again. The vessels that bring the blood back to the heart are called veins. The veins are not under the same amount of pressure that your arteries are so they have thinner walls and a series of valves. These valves in combination with the contraction of your muscles helps push the blood back towards your heart. When it reaches the heart it is immediately sent to the lungs where it enters a huge network of capillaries that allow for the carbon dioxide to be sent to the lungs to be exhaled and allow the lungs to send over the oxygen you just inhaled.

 

Every time your heart contracts it is sending blood out into your arteries. In order for your blood to be able to be pushed out to enter your body’s cells you need to maintain a certain amount of pressure in these vessels. In contrast if these vessels are under too much pressure then this puts high strain on both the vessels and the organs that they are bringing the blood to. This is why a blood pressure reading can be so helpful. As you know when you are at your doctors appointment and they place that cuff on your arm it squeezes and then relaxes on your arm and the technician then says two numbers to you- like you are supposed to know what that means haha!

 

So they will give you a high and a low number. If you see it written down it will say “high number/low number.” The high number is the amount of pressure that your vessels are under when the heart contracts. The low number is the amount of pressure that your vessels are under at rest (so constantly). If you have low blood pressure (for example someone who is losing blood due to an injury) you are at risk of not having enough pressure in your vessels to get the blood into your body’s organs. When you have high blood pressure your vessels and the organs they serve are under constant stress that over time can cause “wear and tear” on them.