Human Circulatory System

The human circulatory system, also known as cardiovascular system or vascular system, is an organ system that allows blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, to all the cells in the body. This is crucial for providing energy to the body, fighting infections, stable temperature and pH and maintaining homeostasis.

Human circulatory system 

The human circulatory system consists of a muscular chambered heart, a network of arteries and blood vessels, which circulates fluid.

Role of the human circulatory system

The function of the circulatory system is to carry blood throughout the body. This circulatory system keeps healthy organs and tissues and keeps us alive.

The circulatory system helps our bodies get rid of waste including:

• Carbon dioxide
• Some toxic chemicals that are produced by the organs of our body
• Toxic waste from our food and beverages

Working of the human circulatory system

Our circulatory system works with the help of blood vessels, including arteries, veins and capillaries. These vessels work together with the lungs to circulate blood in our body. Here’s how:

• It begins in the right ventricle which sends the blood into the pulmonary trunk (lungs) by pulmonary artery. Pulmonary artery is the only artery carrying deoxygenated blood
• The blood flowing to the lungs, becomes oxygenated and returns to the heart (left atrium) through the pulmonary vein. Pulmonary vein is the only vein carrying pure blood
•  Left ventricle pumps the blood through aorta into the body
• The aorta divides into arteries, arterioles finally to capillaries and thereby supplies oxygenated blood to various parts of the body
•  From there deoxygenated blood is collected by veinules which join to form veins and finally vena cava and pour blood back into the heart
•  Arteries are the blood vessels which carry blood away from the heart to various organs of the body
•  Since the blood emerges from the heart under high pressure
• Veins collect the blood from various organs and bring it back to the heart. They do not need thick walls, instead they have valves that ensure that the blood flows only in one direction i.e. from organs to heart

Components of the human circulatory system

The components of the human circulatory system are:

• The heart is a mesodermally formed organ, located in the chest area, between two lungs, slightly tilted to the left. It has the size of a folded fist
• Blood vessels include our arteries, blood vessels and capillaries
• Blood is the interconnected tissue that includes the fluid matrix, plasma and structural components

The Heart

The human heart is a muscular organ situated in the middle of the chest – somewhat to one side of the sternum (breastbone). It sits between your lungs and is encased in a Double circulation walled sac called the pericardium. The pericardium serves to secure the heart and anchor it inside the chest. An adult heart weighs 250-350 g and is often said to be of the size of a fist. 

The human heart has four chambers: two upper chambers (the atria) and two lower ones (the ventricles). The right chamber and right ventricle make up the “right heart” and the left chamber and left ventricle make up the “left heart.” Partition between the right and left auricles is called “interauricular septum” and between right and left ventricles is “inter ventricular septum”.

The heart functions as the pump in the circulatory system. Thus, it maintains a continuous flow of blood throughout the body.

The Blood Vessels

The vessels are an organisation of pathways. It is through these pathways that blood goes all through the body. The two essential kinds of veins in the body’s circulatory system are arteries and veins.

Arteries

• Arteries are veins that transport oxygenated blood from the heart to different body parts
• They are thick, versatile and are isolated into a little organisation of veins called vessels
• Pulmonary arteries transport deoxygenated blood to the lungs

Veins

• Veins are vessels that transport deoxygenated blood towards the heart from different body locations
• They are thin and lie near the outer layer of the skin

Capillaries

• Capillaries form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins)

Blood

• Blood is the body’s liquid connective tissue and it forms an essential part of the human circulatory system
• Its primary function is to carry supplements, chemicals, minerals and other fundamental nutrients to various body parts. 
• Platelets, blood plasma, proteins and other minerals (like sodium, potassium and calcium) comprise human blood

Blood is made of

Plasma

The plasma consists of water (90% & above) inorganic substances. In the plasma RBCs, WBCs and blood platelets float. Inorganic salts (09%) are also present. The organic substances are glucose, amino acids, proteins, hormones, digested and waste excretory products. The blood proteins (7%) are fibrinogen, albumin, globulin and prothrombin.

Red blood cells (RBC)/ Erythrocytes

Red blood cells are predominantly engaged with shipping oxygen, supplements and different substances to different pieces of the body. These blood cells eliminate waste from the body.

The number of RBCs is about 5.5 million in 1 ml of blood. The total number of RBC is about 30 billion. Each RBC is a biconcave disc-like structure devoid of nucleus. The mammalian erythrocytes do not possess nuclei, mitochondria and endoplasmic reticulum. The lifespan of a RBC is 120 days.

White blood cells (WBC)/ Leukocytes

They are true cells. The number of leukocytes is comparatively fever i.e. one ml of blood contains 5000 – 10000 leukocytes in humans. Their life span is 1 to 2 days. The total number of WBCs is about 75 millions. These are large in size and contain nuclei. 

White platelets are particular cells that work as a body’s protection system. They help form immunity by battling off microbes and harmful microorganisms.

Platelets/ Thrombocytes

Platelets are produced from giant cells called megakaryocytes. These are small and without nuclei. Their numbers vary from 0.15 to 0.45 million in 1ml of blood. Their normal life span is one week. The process of clotting is called coagulation. These help in blood clotting at the site of injury by liberating thromboplastin or thrombokinase that ultimately form in soluble microscopic threads of fibrin. 

Circulatory system disorders

• High Signal (High Blood Pressure): High blood pressure is the name of the most important sign (120/80). At this rate 120 torr (millimetres of mercury pressure) is systolic or pump pressure and 80 torr is diastolic or resting pressure. If repeated testing of the vital secret sign is 140/90 (140 over 90) or more it indicates high blood pressure. Significant high blood pressure results in heart disease and affects vital organs such as the brain and kidneys

• Coronary Artery Disease (CAD): Commonly referred to as atherosclerosis, affects the arteries that supply blood to the intestinal muscle. It is caused by the accumulation of calcium, fat, cholesterol and fibrous tissue, which narrows the lumen of the arteries

• Angina: Also called ‘angina pectoris’. Symptom of severe chest pain.It appears when there is not enough oxygen at the risk of heart failure. Angina is possible for men and women of any age but it is most common in the middle middle-aged and older. Occurs due to circumstances affecting blood flow

• Aneurysms: Aneurysms occur when the artery wall becomes weak and stretchy. A weak area can explode as blood travels through a vein. Aneurysms can affect any artery, but aorta aneurysms, abdominal aorta aneurysms and brain aneurysms are the most common

• Plaque deposits: High cholesterol and diabetes can cause fats and other substances that accumulate in the blood. These substances form deposits called plaques on the walls of the artery. This condition is atherosclerosis, or narrowing of the arteries. Atherosclerosis increases the risk of blood clots and stroke, arterial coronaria, coronary artery disease (and other arterial diseases), heart attacks and kidney disorders

• Venous Disease: Venous diseases often affect the arteries within the lower body. Complications such as chronic venous insufficiency and varicose veins occur when blood cannot flow back into the intestines and into the arteries of the leg. Deep vein thrombosis (DVT), an internal grume, can cause life-threatening embolism

Conclusion

Our circulatory system plays a critical role in keeping you alive. Our veins help our body get rid of waste products. Conditions like high blood pressure, high cholesterol and atherosclerosis can affect the health of our circulatory system. If you have one of these conditions, talk to our healthcare provider about steps you can take to protect our cardiovascular health.