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The cardiovascular system consists of:
- the heart;
- blood vessels (veins, arteries, and capillaries); and,
- approximately five liters of blood.
This remarkably efficient system transports oxygen, nutrients, hormones, and waste products throughout the body. As it works tirelessly for us, it not only provides nourishment but it also helps to fight diseases.
The heart is the body’s hardest-working organ. About the size of a fist, it tirelessly pumps blood through your body every single minute.
There are actually two circulation loops:
The pulmonary circulation system transports deoxygenated blood from the heart to the lungs; the blood picks up oxygen in the lungs and returns to the heart.
The systemic circulation loop carries oxygenated blood from the heart to all of the tissues of the body (except the heart and lungs). It removes wastes from body tissues and returns deoxygenated blood to the heart.
The Sum of its Parts
While the heart is the centre of the cardiovascular system, it cannot do its work without the other parts of the system.
Arteries carry oxygen to the body. They begin at the aorta, a large artery near the heart, and then branch into arteries throughout the body.
Veins carry waste material back to the heart. There are two major veins: the superior vena cava (draining areas above the heart) and the inferior vena cava (taking from areas below the heart). Both veins empty into the right atrium. You can see these two major veins on the diagram below.
Capillaries assist in the final exchange. They are very small blood vessels that create a network between the arterioles and venules. 2
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. There is one atrium and one ventricle for each circulation, and with both circulation loops there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle.
Path of Blood as it Travels
So let's put this all in perspective. The movement of blood is a loop, so we can start anywhere on that loop and describe where the blood goes. Here it is:
The blood coming from the lungs to the heart collects in the left atrium of the heart. As it fills, the walls contract and this forces the mitral valve to open. With the valve open, blood rushes into the left ventricle of the heart.
As the left ventricle fills with blood, the mitral valve is forced closed and the muscle of the left ventricle contracts. That opens the aortic valve and squeezes the blood to the aorta which takes blood to all parts of the body.
At this point in the cycle, the blood is under high pressure which allows it to get to the different parts of the body quickly.
As the blood returns from the body, it collects in the right atrium of the heart. As it fills, the walls contract and this forces the tricuspid valve to open. Blood moves into the right ventricle of the heart.
As the right ventricle fills with blood, it forces the tricuspid valve to close. The muscle contracts, opening the pulmonic valve and squeezes the blood through the valve and on to the lungs.
While circulating through the lungs, the blood will replenish itself — getting more oxygen while getting rid of carbon dioxide — and then return to the left side of the heart to begin the cycle again.
Many cardiovascular diseases are related to a person's lifestyle choices, including exercise routines, dietary, and choosing to smoke or not to smoke. There are also some congenital and genetic conditions over which we have little control.
Here are some of the most common diseases that occur in the cardiovascular system:
Atherosclerosis — small plaques build up in the walls of the arteries. If they are too big or too numerous, they may block the artery. Atherosclerosis is also associated with aneurysm formation 3 or splitting of arteries 4.
Acute coronary syndromes — diseases that have a sudden loss of oxygenated blood to the heart tissue.
Thrombus— clots can originate in veins or arteries, and they may travel to various parts of the body. Deep venous thrombosis, which mostly occurs in the legs, sometimes occurs when a person sits for a long time (such as a long airplane flight). If the clot blocks blood flow, a stroke may be the result.
Congential heart defects — These are not associated with diseases; they are usually anatomical variations which occur at birth.
Taking Care of your Cardiovascular System
The benefits of exercise in preventing heart disease are well-researched. My article, Exercise and Heart Disease, discusses how exercise will help to keep your heart and the cardiovascular system healthy. Click on the link to read the entire article.
The following points come from an article on LiveStrong.com 5:
- People with sedentary lifestyles are 45 percent more likely to develop coronary artery disease than people who exercise regularly;
- Exercise is one of the top medication-free strategies to prevent heart disease;
- Physical activity helps you control your weight, blood pressure, cholesterol, diabetes, even stress and smoking;
- People who start exercising after having a heart attack have better rates of survival and a better quality of life.
Eating healthy and exercising often will help to keep your cardiovascular system working well.
I am a BCRPA-certified fitness instructor in Vancouver, BC. I teach four classes at the West End Community Centre in Vancouver, BC, mostly designed for the older adult. The Inevitable Disclaimer: Everything published here expresses only my opinion, based on my training and research. What you do with the information is entirely your own responsibility. I am not liable for any injury you suffer that seems to be related to anything you read here. Always consult your doctor before beginning an exercise program. For other articles, return to the table of contents.
These three dots behave exactly like a footnote. Click on them and you will get more information about the topic. ↩
An arteriole is a small diameter blood vessel that branches out from an artery and leads to capillaries. A venule is a very small vein, which collects blood from the capillaries. ↩
Enlargement of an artery caused by a weakening of the wall. ↩
Sometimes called Spontaneous Coronary Artery Dissection (or SCAD). ↩