Know Your Blood Circulatory System And Its Disorders

Get To Know Your Blood Flow And Circulation - DoctorOnCall

Have you ever wondered how the blood in your body flows non-stop? Human blood flows throughout the body through a system called the human circulatory system. The circulatory system in the human body is an amazing gift from God. This system circulates blood that carries oxygen, nutrients, hormones and various important components throughout the body to ensure the survival of a human being. In addition, it serves to carry waste products out of the cells and also protects the body from infection. The circulatory system in our body works without us realizing it. Do you realize how important this system is?  Let's explore more about the human circulatory system through this article. 

What Organs Are Involved In The Human Circulatory System?

1. Heart 

The heart is an important organ that pumps blood throughout the body. The heart is located in the human chest cavity and about the size of a human fist. However, this fist-sized organ beats 100,000 times a day, pumping five or six liters of blood per minute, or about 2,000 gallons a day! The heart is divided into four chambers, which are two atriums and two ventricles. The left ventricle of the heart is the space that has the strongest muscles and it pumps oxygen-rich blood throughout the body. Left ventricular contraction indicates human blood pressure. The heart also has four valves that prevent backflow of the circulation.

2. Blood Vessels

Blood vessels are cylindrical-shaped organs, like pipes but have an outer and inner surface that is elastic and able to traverse between the bones and other organs. This unique form of blood vessel makes it easy for blood to flow from the heart to the whole body or from the whole body back to the heart. There are several types of blood vessels, which are:

  • Arteries

Arteries transport blood from the heart to all tissues and organs in the human body such as the liver, pancreas and kidneys. Most arteries contain oxygenated blood except for the pulmonary artery that carries deoxygenated blood to the lungs. Blood will flow from the arteries which will then branch into smaller arteries and flow further into the organs of the whole body. These small arteries are called arterioles. The arteries have small lumens and thick muscular walls. Thus, blood can flow rapidly at high pressure to form a pulse. 

  • Veins

Veins transport blood back to the heart and most of them transport deoxygenated blood except for the pulmonary vein that transports oxygenated blood from the lungs to the heart. The veins have thin muscular walls and large lumen. The vein will become larger as it gets closer to the heart. The large veins are:

  • The superior vena cava - the large vein that carries blood from the head and arms to the heart

  • The inferior vena cava - the large vein that carries blood from the abdomen and legs to the heart 

The veins also have a valve structure in them. Since venous blood flow is slow, this structure is important to avoid backflow. 

  • Capillaries

Capillaries are small blood vessels that connect arteries and veins. Capillaries provide nutrients and oxygen to the body's cells and transport carbon dioxide and waste products from the cells. Its thin walls allow the exchange of oxygen, nutrients, carbon dioxide, and other wastes to take place easily. The size of the capillary lumen is very small.

How Does the Human Circulatory System Work?

The circulatory system transports nutrients and oxygen to all cells in the body. The circulatory system has two interconnected systems, namely the systemic and pulmonary circulation. These two types of circulatory systems work together to ensure the survival of a human being. Systemic circulation connects the heart to the rest of the body. This system serves to supply organs, tissues and cells with oxygen and other essential substances. Pulmonary circulation connects the heart and lungs. The heart pumps non-oxygenated blood to the lungs so that carbon dioxide and waste products can be removed in exchange for oxygen. This blood then transports oxygen from the lungs to the heart before being pumped throughout the body by systemic circulation. The deoxygenated blood will then brought back to the heart and ready to be pumped to the lungs again. 

The human circulatory system begins when the heart rests between two heartbeats. Blood flows from both atriums (space in the upper part of the heart) to the ventricle (space in the lower part of the heart), which then expands. The next phase is the ejection period, which is when both ventricles contract and pump blood out of the heart. 

In systemic circulation, the left ventricle pumps oxygenated blood to the main artery, the aorta. Blood flows from the main artery to the larger and smaller arteries next to the capillary network. There, the blood releases oxygen, nutrients, and other important substances to the cells and takes in carbon dioxide and waste products that the body does not need from it. After that, deoxygenated blood will be collected into the veins and move towards the right atrium and also to the right ventricle.

Next, this is when the pulmonary circulation begins. The right ventricle pumps deoxygenated blood to the pulmonary arteries, which branch into smaller arteries and capillaries. Capillaries form fine tissue around the alveoli (air sacs like grapes at the end of the human respiratory tract, namely bronchioles). This is where carbon dioxide is released from the blood into the alveoli, and the oxygen inhaled during breathing enters the bloodstream. During human respiration, while oxygen enters the airways, carbon dioxide is removed from the body. Oxygen-rich blood travels through the pulmonary veins and left atrium to the left ventricle. The next heartbeat will start a new cycle of systemic circulation again and so on for the rest of your life!

Disorders In The Human Circulatory System

There are various types of diseases associated with the human circulatory system. These diseases can be related to any organs involved in this system, either the heart, blood vessels or both. Disorder in one of the circulatory organs will indirectly affect the other organs including the lungs and other organs in the body. The following is a list of diseases associated with disorders of the human circulatory system:

  • Atherosclerosis

Atherosclerosis is a disease caused by the hardening of arteries. This is due to the formation of plaques on the walls of the arteries. The plaque structure contains cholesterol, other fatty substances, fibrin, cellular material and also calcium. The larger the plaque on the artery wall, the narrower this blood vessel becomes. This causes high blood pressure which also affects kidney and heart function. Besides, small plaques can be detached from large plaque structures and clog the small capillaries. This causes ischemia or stroke if it occurs in the brain. 

  • Heart attack

As described above, plaque can come off and clog other blood vessels. If this occurs in the coronary arteries in the heart it will cause a heart attack or myocardial infarction.

  • Angina pectoris

Angina pectoris occurs when the heart does not have an adequate blood supply. Angina means pain, while pectoris means chest. As the name implies, the symptom that appears is chest pain and most patients describe this pain as a weight or as a band being tightened around their chest. Other symptoms may include fatigue, nausea and shortness of breath. 

  • Arrhythmia and dysrhythmia

Arrhythmia means that the heart has an abnormal heart rhythm. The same goes for dysrhythmia. When there is a disturbance in the heartbeat, this indicates that there is a disturbance in the process of contraction and relaxation of the heart which then will also affect the circulatory system in the body.

  • Heart valve problems

Heart valve disease can affect the circulatory system too. Heart valves can either become hard and stiff (stenosis) or loose and weak (regurgitation). Valve problems will cause the pumping of blood inefficient.

  • High blood pressure

Hypertension or high blood pressure is a disorder of the circulatory system that can occur due to other problems such as atherosclerosis or other health problems. High blood pressure can affect the heart muscle and other organs such as the kidneys and eyes in the long run. Know your risk for high blood pressure here!


The circulatory system is a very important system in the human body. If there are problems related to this system, it will result in various serious diseases. Thus the practice of a healthy and balanced diet as well as regular physical activity is important to maintain the function of the circulatory system. Consult a doctor to learn more about our circulatory system.

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