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Exploring the Complexities of the Circulatory System: Anatomy, Functions, and Health Implications

Jul 9, 2022

What Is The Circulatory System?

In conjunction with the cardiovascular system, the circulatory system functions to aid in illness prevention maintain a core body temperature and supply the proper chemical equilibrium for the body to attain homeostasis or a state of equilibrium among all its systems.

You must be wondering about what is the circulatory system made up of. It is made up of the following circulatory system organs.

  • Heart
  • Blood 
  • Veins
  • Arteries 

Refer to the above-given circulatory system diagram to understand the parts of the circulatory system.

The Heart And Its Role



The heart is a vital circulatory system organ. It is located towards the middle of the chest and is roughly the size of two adult palms. The heart keeps the functions of the circulatory system constant because of its constant pumping.

Wall of The Heart

The heart wall is made up of three layers:

  • The epicardium is the outside layer of the heart wall
  • The myocardium is the intermediate (and muscular) layer
  • The endocardium is the innermost layer


The heart is divided into four compartments: the right and left atria and the right and left ventricles. They form the interior cavity of the heart. The four chambers are crucial in circulation. 

The atria collect blood from the veins, whereas the ventricles expel blood from the heart. The ventricles’ myocardial layers are thicker than the atria because they must be stronger to conduct this pumping action.


The Arteries And Their Role 

Arteries are vessels that transport blood out from the heart. There are three layers to the artery walls: 

  • Tunica intima (inner)
  • Tunica medium (middle)
  • Tunica external (outer)

Typically, the middle layer is the thickest. It is a smooth muscle that regulates blood flow by changing the size of the artery.


Arteries are classified into three categories. The arteries further get smaller and smaller as they move away from the heart. 

1. Elastic arteries

The elastic arteries are the pulmonary arteries and the aorta. They get blood straight from the heart and must be elastic to handle the rise and constriction of blood with each heartbeat. 


The aorta is the essential artery in the body. The right ventricle delivers blood containing carbon dioxide to the lungs via the pulmonary arteries. They are the only arteries in the body that conveys deoxygenated blood.

2. Muscular arteries 

The muscular arteries transport blood from the elastic arteries to the rest of the body. They are formed of smooth muscle that may contract and expand when blood flows through them. Muscular arteries include the coronary and the femoral arteries.


3. Arterioles

The arterioles are the tiniest arteries and transport blood from the muscle arteries to the capillaries. The capillaries unite the arteries that carry blood away from the heart with the veins that carry blood back to the heart.

The quantity of material exchange determines the number of capillaries in a bodily system. Because their biological systems require a lot of nutrients and oxygen, the liver, skeletal muscle, and kidney all contain a lot of capillaries. One part of the eye with no capillaries in the cornea.

The Veins And Their Role


Through veins, blood returns to the heart. Blood flows from the capillaries into the venules, the tiniest veins. The veins grow in size as the blood gets closer to the heart. Veins, like arteries, contain three layers of wall termed as:

  • Tunica media 
  • Tunica intima
  • Tunica externa. 

There are some significant distinctions between arteries and veins:

  • The walls of veins have far less connective tissue and smooth muscles.
  • Vein walls are narrower than artery walls.
  • Veins have lower pressure and may accommodate more blood than arteries.

The veins contain around 70% of the body’s total blood supply at any given moment.

The above-given circulatory system diagram will help you understand the role of veins properly. 


The veins have valves and little bits of tissue that ensure blood flows in the proper direction. The medium and big veins’ valves keep blood moving towards the heart. These valves ensure that gravity does not incorrectly draw blood into the legs and arms.

The heart contains four valves which are as follows: 

  • The tricuspid valve connects the right ventricle to the right atrium. 
  • The mitral valve (bicuspid valve) connects the left ventricle to the left ventricle.
  • The pulmonic valve connects the right ventricle to the pulmonary artery. 
  • The aortic valve is a valve that connects the left ventricle to the aorta.

The Blood And Its Role


Almost everything in the body is transported by blood. It is an important circulatory system organ. It transports hormones, nutrition, oxygen, antibodies, and other vital substances throughout the body. The blood is made up of four major components.

The circulatory system diagram will help you understand the type of blood cells in the circulatory system.


Plasma accounts for approximately 55% of the blood. Plasma is responsible for the fluidity of blood. Plasma circulates blood cells throughout the body via the circulatory system. It also transports nutrition, hormones, antibodies, and waste products. Plasma is made up of the following elements:

  • Salts
  • Sugars 
  • Proteins 
  • Fats 
  • Water 

Red blood cells

Red blood cells are also known as erythrocytes. They account for 40 to 45 per cent of the amount of blood. Because these cells lack a nucleus, they may readily alter form as they travel through the body’s arteries and veins.

Haemoglobin is a kind of protein found in RBCs. It transports oxygen from the lungs to the remainder of the body while returning carbon dioxide to the lungs. The carbon dioxide is expelled.

White blood cells

White blood cells are commonly known as leukocytes. They make up only 1% of the blood. They defend the body against infection. There are five kinds of white blood cells.

  • Neutrophils 

 Neutrophils are among the immune system’s first cells that activate when microbes such as viruses or bacteria enter the body. They go to the infection site, consuming the germs and releasing enzymes that destroy them. Neutrophils also stimulate the activity of other immune cells.

  • Lymphocytes

Lymphocytes are further of two types:

  1. B lymphocytes (B cells): B lymphocytes produce antibodies.
  2. T lymphocytes (T cells): T lymphocytes control other immune cells and attack infected cells and malignancies
  • Basophils

Basophils help with “immune monitoring.” This implies they can help discover and eliminate some developing cancer cells. During an allergic reaction or an asthma attack, basophils also release histamine in their granules, which is vital.

  • Eosinophils

Eosinophils are white blood cells that are part of the immune system and help fight sickness and infection when functioning appropriately. However, having an excessive number of activated eosinophils may lead to disease pathogenesis and a self-perpetuating loop of damage and inflammation in various chronic disorders.

  • Monocytes

A kind of immune cell that is produced in the bone marrow. They flow through the blood to tissues throughout the body, where it matures into a macrophage or dendritic cell. Macrophages surround and destroy germs, and material, eliminate dead cells, absorb foreign and increase immune responses.

  • Platelets

Platelets, also known as thrombocytes, are fragments of cells. Platelets are required for blood clot formation. They adhere to a wounded blood artery lining, forming the foundation for a clot. This helps to halt the bleeding and promotes healing.

Functions Of The Circulatory System 

The lungs’ thin membranes absorb oxygen when breathed, allowing oxygen to enter the circulation. The body produces carbon dioxide as it utilises oxygen and processes nutrients, which your lungs release when you exhale.

The circulatory system functions due to continual pressure from the heart and valves located throughout the body. This pressure keeps veins carrying blood to the heart and arteries transporting blood away from the heart. 

Three kinds of circulation take place in the human body:

  • Pulmonary circulation: This portion of the cycle transports oxygen-depleted blood from the heart to the lungs and then back to the heart.
  • Systemic circulation: This is the section that transports oxygenated blood from the heart to various body regions.
  • Coronary circulation: This form of circulation supplies oxygenated blood to the heart, allowing it to operate effectively.

Symptoms of Inadequate Circulation

The symptoms of inadequate circulation system function are as follows:

  • Pain in chest
  • Feeling faint
  • Dyspnea 
  • Weakness, pain or numb extremities
  • Swallowing in limbs
  • Irregular heartbeat
  • Palpitations
  • Fatigue

The symptoms vary according to the kind of cardiovascular problem. Peripheral arterial disease, for example, can cause leg and foot symptoms such as:

  • Cramps in legs while resting or walking
  • Cold legs or feet
  • Change the colour of the leg
  • Change in thickness or colour of toenail
  • Hair on feet and legs
  • Non Healing ulcers on the feet and legs


The normal function of the circulatory system is essential to your survival. Blood arteries transport oxygen-rich blood to the lungs. The heart then sends oxygen-rich blood to the remainder of the body via arteries. Your veins assist your body in eliminating waste. Excessive blood pressure, atherosclerosis, and high cholesterol can all impact your circulatory system’s health. Every student must learn about the circulatory system in depth so that they can gain knowledge about the subject and score more in the exams.

Circulatory System


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