Circulatory System

The circulatory system in humans is a network of blood vessels through which the heart pumps the blood and keeps the blood in circulation. The circulation system provides blood to each cell in the body.

There are two categories of blood vessels – arteries and veins. The arteries carry the oxygenated blood from the heart to the rest of the body where it distributes the oxygen and nutrients. The veins carry the deoxygenated blood from the body organs back to the heart. The heart pushes the deoxygenated blood to the lungs, where the blood exchanges the carbon dioxide with fresh oxygen and is returned to the heart for recirculation to the body organs. When the blood reaches the intestines, it collects nutrients for distribution and discards the waste collected from the body cells to the intestines. The blood carries the oxygen and the nutrients to the tissues of the body where it exchanges them with carbon dioxide and waste from the cells. Waste like toxins are released into the kidneys.

Another important role of blood is to carry the white blood platelets that have the capacity to fight germs and contain diseases to the infection areas. Therefore, blood helps the immune system of the body.

The circulation system therefore aids some of the other organ systems like the respiration system, the digestive system, the immune system and the excretory system.

Therefore, as you must have noticed, the main parts of the circulation system are:

1. Heart

2. Blood Vessels

3. Blood

4. Lymph

The Heart

The heart is a special involuntary muscle called the cardiac muscle. Involuntary muscles keep working on their own without our intervention or effort.

The heart is divided into two sides divided by the septum. Each side has two chambers – a ventricle and an attrium. The left side of the heart is responsible for pumping the oxygenated blood from the lungs to the rest of the body. The right side of the heart is responsible for bringing the deoxygenated blood back to the lungs.

The heart keeps beating rhythmically using an electrical signal from the sinoatrial node located at the top of the heart. An electrocardiograph machine can record these electric impulses to study the performance of the heart.

The heart is a very important part of the circulatory system. If a part of the blood is lost, one can survive as the blood can get regenerated very quickly. However, any damage to the heart can be fatal. The heart is made up of involuntary cardiac muscles that keep the heart beating without any manual intervention as long as it remains healthy.

Blood Vessels

The cardiovascular system part of the circulatory system is a closed network of blood vessels through which the blood keeps circulating due to the action of the heart. The blood vessels that carry the oxygenated blood away from the heart to the body organs are called the arteries. The blood vessels that collect the deoxygenated blood and bring it back to the heart are called the veins.

The blood vessels are thick near the heart and divide into smaller arteries and finally into capillaries that are only one cell layer thick. Just to compare, the largest arteries called the aorta and the largest vein called the vena cava are each about an inch in diameter!

Blood

The blood is composed of a fluid called plasma that contains red blood cells, white blood cells and platelets. The plasma carries the proteins, hormones and minerals from one part of the body to the other. The red blood cells contain hemoglobin which helps to transport oxygen from the lungs to the rest of the body parts. The white blood cells help to fight infections and diseases. The blood platelets help to clot after an injury thereby preventing an excess loss of blood.

Lymph

When the blood carries the nutrition to the individual cells and collects waste, it forms the interstitial fluid between the cells of a tissue to transfer the nutrients to the cells. The lymphatic system is a network of one way vessels that collect the interstitial fluid called lymph into the lymph vessels which push the lymph by rhythmic contractions through several lymph nodes on the way into the subclavian veins where the lymph mixes back with the blood.