On average, our body has about 5 liters of blood continually travelling through it by way of the circulatory system. The heart, the lungs, and the blood vessels work together to form the circle part of the circulatory system.
Circulatory system or also known as Cardiovascular System is another system in your body that can affect your health. But, before we proceed to its effect to our health, let us learn further about the circulatory system.
Circulatory system or also known as Cardiovascular System is another system in your body that can affect your health. But, before we proceed to its effect to our health, let us learn further about the circulatory system.
WHAT IS MEANT BY ‘CIRCULATORY SYSTEM’?
Circulatory System is the distribution of blood throughout our body. Furthermore, it is the combined function of the heart, blood, and blood vessels. This functional combination is used to transport oxygen and nutrients to organs and tissues throughout the body and carry away waste product.
Human and other vertebrates have a closed circulatory system, which means the blood never leave the network of arteries, veins, and capillaries.
THE BLOOD
Before we learn deeper in circulatory system, let us learn about the blood first as the main purpose of the circulatory system. Blood is a very essential element in our body; otherwise our body will stop working if there is no presence of blood in our body.
Blood plays a very important role in our body, which make it suitable to call blood as the element of life, growth, and health. Blood carries oxygen from our lungs to the body cells and carries carbon dioxide from the body cells to our lungs. Blood also transports nourishment from digestion and hormones from the glands. Blood also contain disease fighting substance to the tissue.
An average adult body contains about five quarts of blood.
An average adult body contains about five quarts of blood.
If you think blood is the same as other liquids, you are totally wrong. Blood consists of a fluid that has different types of cell surrounding it, which are the Red Blood Cell (RBC), the White Blood Cell (WBC), and the Plasma. Plasma comprises 55% of the blood volume, which is the fluid part of the blood. The remaining 45% is made up of RBC, WBC, and the platelets.
The Red Blood Cells (RBC)
Red Blood Cells perform the most important duty of the blood. Do you know that there are five million red blood cells in each cubic millimeter of blood? A single drop of blood contains millions of red blood cells which is constantly travelling through our body to deliver oxygen and removing waste.
Why does the red blood cells colored red? It is because the presence of the protein chemical called as hemoglobin which is iron-containing and bright in color. When the blood passes the lungs, oxygen molecules attach to it, and are release as it passes through the body’s tissue. The empty hemoglobin then bond with the tissue’s carbon dioxide and other waste material, and transporting it away.
The Red Blood Cells have a perfect shape to carries its function. It has a flattened biconcave shape and also thinner on its center rather than its edge, therefore Red Blood Cells have more surface area in order to absorb and transport oxygen faster. It also does not have a nucleus to give it more space for the hemoglobin. As more hemoglobin is carried, it also could carry more oxygen.
As Red Blood Cells do not have nucleus, it has a definite lifespan, which is 120 days or around 3-4 months. You might think if Red Blood Cells died, we will lose one cell. No! Red Blood Cells are produced in the bone marrow periodically to replace the died cells. Red Blood Cells are destroyed in the spleen. Hemoglobin that released from the destroyed Red Blood Cell will be broken down in the liver.
The White Blood Cells (WBC)
White Blood Cells are bigger than the Red Blood Cells, but they are fewer in number. In each cubic millimeter of blood, there are about only 5000 to 10000 White Blood Cells compare with the Red Blood Cells which can reach 5 million in each cubic millimeter.
Differ from Red Blood Cells, White Blood Cells do not have hemoglobin but it has a nucleus. However, White Blood Cells have a relatively short lifespan, just a few days until few weeks.
White Blood Cells protect our body from the unwanted substance such as germs, virus, and disease.
Plasma
Plasma comprise 55% of the blood volume in our body, it contains 90% mainly of water and the rest is contains of a mixture of various dissolve substances such as fibrinogen, prothrombin, , antibodies, mineral salts, food substances, excretory products, and hormones.
THE HEART
The heart is the most important organ in the circulatory system. To get the full details of the heart and how the blood flows inside the heart, you can watch the animation below :
The heart is really a muscle that works as a pump to pump the blood to all of our body. It's located a little to the left of the middle of your chest, and it's about the size of your fist.
In fact, the heart circulates the body's blood supply about 1000 times each day and pumps the equivalent of 5000 to 6000 quarts of blood in a day. Can you imagine how amazing our heart is?
In each beat, our heart pumps the blood away. Before the heart beat, the blood fills up the heart first. Then its muscle contracts to squirt the blood along. The heart does this all day and all night, all the time
The human heart consists of four sections, called chambers. There are two on each side of the heart, two on top and two underneath. On top there is a left atrium and a right atrium. The two together are called atria. These section is filled with blood that is returning from the body and lungs. Underneath the atria are the left and right ventricles. They pump out the blood to go to the body and lungs. The left and right sides of the heart are separated by a thick wall of muscle called a septum. This wall prevent the deoxygenated blood to get mixed with the oxygenated blood.
The right side of your heart receives blood from the body and pumps it to the lungs. The left side of the heart does the exact opposite: It receives blood from the lungs and pumps it out to the body.
CIRCULATORY PATHWAY
Human circulatory system mainly comprise of heart, the blood vessels, and the blood itself. In human and other mammals, there is a double circulation which means that the blood passes through the heart twice in a complete circuit. The double circulation consists of the pulmonary circulation and systemic circulation.
· Pulmonary circulation is the blood circulation from the heart to the lungs and back
to the heart again. The deoxygenated or oxygen poor blood enters the right atrium through the Superior and Inferior vena cava. Then the blood is pumped through the tricuspid valve to the right ventricle. From the right ventricle, blood is pumped to the left and right pulmonary arteries, one for each lung. In the lungs, the oxygen poor blood becomes the oxygen rich blood by the process of gaseous exchange in the bronchioles. The blood then leaves the lungs through the pulmonary veins and return to the left section of the heart and pulmonary cycle is now complete.
Left ventricle → Aortic semilunar valve → Left Atrium → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins (Superior and Inferior vena cava) → Right atrium
The combination of pulmonary circulation and Systemic circulation make up our blood circulation in our body. Let us see the video below to trace the path of the blood flow in our body
Additional Information Links
1. Complete definition about circulatory system (Link 1) :
2. Complete discussion about circulatory system (Link 2) : http://eliot.needham.k12.ma.us/technology/lessons/cir_sys/index.htm3. Heart discussion with animation :
http://www.smm.org/heart/heart/top.html
Resources
1. Microsoft Encarta 2003
2. Biology Matter Text Book
