Understanding the blood flow through the heart is a topic you need to learn in nursing school. Memorizing and understanding it by heart will save you from headaches when trying to comprehend the pathophysiology of cardiac diseases.
Like in cases of Myocardial Infarction, Heart Failure, or any other Congenital Heart Disease, you have to understand the normal blood flow through the heart before fully understanding how these diseases came to be. If you understand the normal blood circulation through the heart, it won’t be hard to understand what went wrong or what might happen to the patient.
In this post, we’ll explain to you how the blood flows through the heart—where the blood enters, where the oxygenation happens, and its exit point. We’ve included tips and techniques for you to understand them easily!
Anatomy & Physiology
Before we tackle the blood flow through the heart, let’s first review the anatomy and physiology involved.
- Pulmonary Circulatory System: It is responsible for the circulation of unoxygenated blood from the heart going to the lungs (passing the pulmonary artery). Oxygenation of the blood takes place in the lungs, then returns to the heart (already oxygenated) via the pulmonary vein.
- Systemic Circulatory System: It is responsible for circulating the oxygenated blood that came from the heart into the body, systems, organs, and tissues.
- Cardiovascular System: The cardiovascular system is like a pump that has one-way valves and has a system of plumbing tubes where the blood travels.
- Arteries: The oxygenated blood passes through the arteries, then divide going to the arterioles, then divides into much thinner capillaries. When all oxygenated blood reaches all organs and tissues, these capillaries join into veins that will return the blood into the heart.
- Functions of the Heart: The heart’s function is to manage the blood supply, produce pressure for the blood, secure a one-way blood flow, and transmit blood.
Terms to Remember:
- Blood Vessel: It is classified into two: (1) Artery (2) Veins
- Vasodilation: Vaso- means blood vessels, and dilation means opening. So vasodilation means the opening of the blood vessels.
- Vasoconstriction: It is the tightening or closing of the blood vessels.
When keeping track of cardiac activity, here are some vital signs you need to monitor.
- Pulse Rate: The normal cardiac rate is 60-100 beats per minute or 70-76 beats per minute in a normal resting person. If the pulse rate is above normal, this indicates tachycardia, and if it’s the other way around, it’s bradycardia. Any abnormality in your heart may be an underlying sign of a heart ailment.
- Respiratory Rate: The normal respiratory rate for adults is 12-20 breaths per minute. Any abnormality indicates a difficulty in breathing, and it may be caused by the mixing of oxygenated and unoxygenated blood.
- Blood Pressure: The normal blood pressure for an adult is 120/80 mmHg. Anything below and above may indicate that there’s something wrong with the heart’s pumping.
Blood Flow Through the Heart
Now we’ve come to understand the important terms and the physiology of the heart. Let’s proceed with discussing the blood flow through the heart.
The process can be remembered with just 12 easy steps. It flows through the six areas in the right and six areas on the left. The right side is represented by the blue color (meaning, it’s unoxygenated), and the left side is in red (where blood is oxygenated).
The 12 Easy Steps of Blood Flow Through the Heart
|Distribution of oxygenated
blood the whole body
|Receiving of unoxygenated
blood from the organs
|7. Oxygenated blood will enter the lung through the Pulmonary vein
8. Blood enters the Left Atrium
9. It enters the Mitral also known as the Bicuspid valve.
10. The blood is squeezed going to the Left ventricle
11. Oxygenated blood enters the Aortic valve
12. It goes to the Aorta, and the aorta pumps it throughout the body.
|1. Unoxygenated blood enters the Inferior and Superior Vena Cava
2. Unoxygenated blood is emptied in the Right Atrium
3. The atrium contracts and the Tricuspid valve opens to enter the Right Ventricle
4. The tricuspid valve closes, the Right ventricle is filled.
5. Blood leaves the heart through the Pulmonic valve.
6. Blood enters the Pulmonary artery, then lungs where it is oxygenated
- All blood passing a VEIN is unoxygenated (except the pulmonary vein). Usually, you see it as BLUE in books or online sources, because if you lack oxygen, you become blue.
- All blood passing the ARTERY is oxygenated (except the pulmonary artery). Usually, you see it as RED in books or online sources, because red is the color of oxygenated blood.
- To assess if the circulatory system functions well, blood pressure, heart rate, and arterial blood gas should be obtained.
- Remember this phrase: “First always TRY, before you BUY.” This is not just applicable when shopping, but it is a phrase to remember to avoid confusion with the Tricuspic and Bicuspid valve. That the Tricuspid (TRY) valve is before the Bicuspid (BUY).
- Atrium/Ventricle: Do not confuse yourself with the placement as well. Just remember that A-Atrium comes first in the alphabet, and V-Ventricle comes last.
- Backflow Prevention: The backflow of blood or the mixing of oxygenated and unoxygenated blood must not occur in the heart, because it will lead to potential complications. How does the heart prevent backflow? Remember this concept: A valve shuts when a ventricle is full. When a valve is not successful in shutting, oxygenated and unoxygenated blood can get mixed and might lead to heart disease.
Now that you have a better understanding of the blood flow through the heart, fully comprehending the pathophysiology of cardiac diseases shouldn’t have to be a harrowing experience, but a much more enjoyable one for you!