Cardiovascular System: Overview
Sections
Notes
The cardiovascular system comprises the heart and blood vessels and circulates blood throughout the body.
- Two key functions of the cardiovascular system:
- Deliver nutrients and oxygen to the body tissues;
- Remove waste, such as carbon dioxide, from the body tissues.
The cardiovascular system can be divided into two distinct, but cooperative, circulatory pathways:
- The pulmonary circulation transports oxygen-poor blood (aka, deoxygenated blood) from the heart to the lungs, and returns oxygen-rich blood (aka, oxygenated blood) from the lungs to the heart.
- Comprises lungs and heart.
- The systemic circulation, which is more extensive, transports oxygen-rich blood from the heart to the rest of the body, and returns oxygen-poor blood from the body to the heart.
- Comprises body tissues and heart.
These two circulatory pathways cooperate to deliver oxygen-rich blood to the body tissues and oxygen-poor blood to the lungs.
Blood vessels
- Transport the blood to and from the target organs and tissues:
- Veins carry blood TO the heart.
- Arteries carry blood AWAY from the heart.
Circulatory pathways:
- Pulmonary veins carry oxygen-rich blood from the lungs to the heart.
- Systemic arteries carry oxygen-rich blood from the heart to the body tissues.
Within the body tissues, oxygen is removed from the bloodstream, and carbon dioxide (and other metabolic wastes) is added to the blood. - Systemic veins return this oxygen-poor blood to the heart.
- Pulmonary arteries carry the oxygen-poor blood away from the heart to the lungs, where gas exchange occurs.
- The pulmonary vein AND the systemic artery carry oxygen-rich blood.
Key points:
- The circulatory system regulates blood flow and pressure; faulty regulation can result in tissue damage and/or death.
- Oxygen-rich and oxygen-poor bloods are physically separated within the body.
- If oxygen-rich and oxygen-poor blood were to mix, the overall oxygen concentration would be reduced, and tissue damage would occur (as it does in some heart conditions).
- If blood pressure is too high, the blood can physically damage tissues.
- If the pressure is too low, tissues will receive insufficient blood flow perfusion.
Full-Length Text
Overview of the Cardiovascular System
Here we will learn the overall structure and function of the cardiovascular system, which comprises the heart and blood vessels. The cardiovascular system is also referred to as the circulatory system, because it circulates blood throughout the body.
To begin, start a table.
Denote two key functions of the cardiovascular system:
It delivers nutrients and oxygen to the body tissues.
It removes waste, such as carbon dioxide, from the body tissues.
Denote that the cardiovascular system can be divided into two distinct, but cooperative, circulatory pathways: Pulmonary and Systemic Circulation.
The pulmonary circulation transports oxygen-poor blood (aka, deoxygenated blood) from the heart to the lungs, and teturns oxygen-rich blood (aka, oxygenated blood) from the lungs to the heart.
The systemic circulation, which is more extensive, transports oxygen-rich blood from the heart to the rest of the body, and returns oxygen-poor blood from the body to the heart.
Let's illustrate how these two circulatory pathways cooperate to deliver oxygen-rich blood to the body tissues and oxygen-poor blood to the lungs.
First, draw the heart, which is at the center of the cardiovascular system.
Above it, write "lungs".
Below, write "body".
Indicate that the lungs and the heart comprise the pulmonary circulation, and the body and heart comprise the systemic circulation.
Then, show that oxygen-rich blood from the lungs travels to the heart via pulmonary veins.
In our table, denote that "veins" are vessels that carry blood TO the heart.
Then, show that from the heart, the oxygen-rich blood is sent to the body via systemic arteries.
Denote that "arteries" are vessels that carry blood AWAY from the heart.
Notice that both the pulmonary vein and the systemic artery carry oxygen-rich blood (which is traditionally indicated by the color red, since oxygenated blood is bright red; deoxygenated blood is darker red, and is traditionally indicated in illustrations by the color blue).
It is important to recognize that vessels are defined as arteries or veins according to whether they deliver blood to or away from the heart, NOT by the concentration of oxygen within that blood.
Indicate that, within the body, oxygen is removed from the bloodstream Show that the body releases carbon dioxide into the bloodstream, and that oxygen-poor blood is returned from the body to the heart via systemic veins.
Show that the heart sends this oxygen-poor blood to the lungs via pulmonary arteries.
Indicate that, in the lungs, carbon dioxide (and other gases) will leave the bloodstream; fresh oxygen will enter the bloodstream, and the cycle will continue.
Finally, let's address the importance of the circulatory system in blood flow regulation; faulty regulation can result in tissue damage and/or death.
Notice in our diagram that the heart and blood vessels regulate the movement of blood within the body; blood does not move directly from the lungs to the body tissues or vice versa.
Denote the following clinically important consequences of this organization:
Oxygen-rich and oxygen-poor bloods are physically separated within the body.
If oxygen-rich and oxygen-poor blood were to mix, the overall oxygen concentration would be reduced, and tissue damage would occur (as it does in some heart conditions).
The circulatory system also regulates the pressure of the blood flow.
If the pressure is too high, the blood can physically damage tissues (imagine watering a garden with a fire hose);
If the pressure is too low, tissues will receive insufficient blood flow perfusion (for instance, when our blood pressure gets too low, we pass out to get better blood flow perfusion to the brain).