A Brief Overview of How Blood Travels Through the Heart
I bet you know that blood carries oxygen throughout the body. However, do you know how blood travels through the heart to get to where it needs to go?
Terms
To understand the journey blood goes through, it is important to define some terms.
- Artery: Blood vessel that carries blood away from the heart
- Vein: Blood vessel that carries blood to the heart
- Atrium: Chamber of the heart located above the ventricles
- Ventricle: Chamber of the heart located below the atria
- Valve: flaps that separate the chambers of the heart to prevent backflow of blood
Stages
Right Atrium:
The first part of the blood circulation process occurs in the right atrium. Deoxygenated blood from the superior and inferior vena cava, the largest vein in the body, funnels into the right atrium. Once enough pressure builds up in the right atrium, the tricuspid valve opens and allows the blood to flow into the right ventricle.
Right Ventricle:
After passing through the tricuspid valve, the blood enters the right ventricle. At this point, the blood is still deoxygenated. To become oxygenated, it must travel to the lungs. To do this, enough pressure has to build up in the right ventricle to open the pulmonary valve. Once opened, the blood travels into the pulmonary artery.
Lungs:
In the pulmonary artery, blood travels into the lungs. Blood has hemoglobin, a protein that allows it to carry oxygen. Tiny air sacs in the lungs, known as alveoli, are where gas exchange occurs. The oxygen-poor blood becomes oxygen-rich and resumes its journey by traveling into the pulmonary veins.
Left Atrium:
Now oxygenated, blood enters the left atrium from the pulmonary veins. When enough pressure builds up in the left atrium, the mitral or bicuspid valve opens to allow the blood to travel into the left ventricle.
Left Ventricle:
Once in the left ventricle, the oxygenated blood must travel out of the heart and to the rest of the body. It must leave the left ventricle through the aortic semilunar valve and flow into the aorta.
Aorta:
The aorta is the largest artery in the body that carries oxygenated blood from the heart to the rest of the body. After traveling throughout the body, the blood becomes deoxygenated and must start its journey again by entering the heart back through the superior and inferior vena cava.
Summary
Deoxygenated blood comes into the right atrium from the superior and inferior vena cava. Then, it passes through the tricuspid valve into the right ventricle where it goes through the pulmonary valve and into the pulmonary artery. From this artery, blood goes to the alveoli in the lungs where gas exchange occurs and hemoglobin picks up oxygen. The oxygenated blood goes into the pulmonary vein where it funnels into the left atrium and then through the mitral or bicuspid valve. After passing through that valve, the blood travels into the left ventricle, out the aortic semilunar valve, into the aorta, and to the rest of the body.
