Circulatory System

Last Updated: December 11, 2023

Featured Image

Table of Contents

The circulatory system is a system within the body comprising blood vessels that carry blood toward and away from the heart. Oxygenated blood is then distributed to organs and tissues around the body from the heart. 

What is the Circulatory System?

The circulatory system, also known as cardiovascular system, has multiple functions, but the main one is to provide oxygen, nutrients, and hormones to muscles, tissues and organs throughout the body. 

Removing waste is also another part, specifically from cells and organs, so that the body can dispose of it.

Anatomy of the Circulatory System

The anatomy of the circulatory system has several parts, including the heart and blood vessels. 

  • The heart: A muscular organ responsible for pumping blood throughout the body. Many pathologies or disease states can affect the heart, which will be mentioned in later sections. 
  • Blood vessels: They contain arteries, veins and capillaries. There are three main types of arteries; elastic retries, muscular arteries, and arterioles. They all appear similar, though they have slightly different functions. 
  • Both arteries and veins can be described as superficial or deep. Superficial meaning is closer to the body’s surface, and deep meaning is further away. Examples include the jugular vein and the pulmonary artery. 
  • Blood: Oxygen rich blood contains red and white blood cells, plasma, and platelets. 

Circulatory System Control of Blood Pressure and Volume

Blood flow refers to movement through a vessel, tissue, or organ. It usually has some unit of time attached to it. Blood flow can be changed by the volume it is flowing in, leading to either an increase or decrease in pressure. 

Arterial Blood Pressure

Arterial blood pressure, or blood pressure in the arteries, has a few distinct components. They are systolic and diastolic pressures, pulse pressure, and mean arterial pressure (MAP).

Systolic Blood Pressure

Systolic pressure, or the top number read on a blood pressure monitor, is the pressure of the heart at work. This work happens when the heart is contracting, trying to move blood throughout the different areas. 

Diastolic Pressure

The diastolic pressure is the lower number or the bottom number. It refers to the blood pressure when the heart is relaxing and resting. The difference between the systolic and diastolic pressure is the pulse pressure. 

The mean arterial pressure (MAP) is then the average pressure of blood in the arteries. There is a specific calculation that is done to calculate this. 

Influences on Changes in Blood Pressure and Blood Volume

Five variables can influence blood flow and blood pressure. They are cardiac output, compliance, the viscosity of the blood, the volume of the blood, and blood vessels' length and diameter.

  • Cardiac Output: Cardiac output is the unit of time directed towards blood flow per minute. Factors influencing cardiac output include sympathetic stimulation, whether hormonally or through other measures. 
  • Compliance: Compliance is the ability of the diameter of a tube to expand to accommodate more volume. The greater the compliance, the more effectively it can expand without resistance. Resistance is the opposition to flow. 
  • Viscosity: Viscosity can cause resistance as it refers to the thickness of a substance. The thicker a substance is, the more it will resist flow. Lastly, blood vessels' length and diameter can influence blood flow and pressure. 
  • Length: The longer the vessel, the greater the resistance and the lower the flow. 
  • Diameter: The wider the diameter, the less resistance there is. 

Interaction of the Circulatory and Respiratory Systems

The circulatory system, as previously mentioned, supports the respiratory system as it brings blood to and from the lungs. The exchange of nutrients and oxygen and removing carbon dioxide are key. 

Air moves in and out of the lungs through structures such as the trachea, bronchi, and bronchioles. Pulmonary circulation happens when blood moves in and out of the lungs through the pulmonary arteries and the veins that connect it to the heart. 

First, veins carry deoxygenated blood to the heart. The pulmonary arteries carry deoxygenated blood from the heart to the lungs. The pulmonary veins carry oxygenated blood back to the heart to be distributed to the body. 

Certain activities speed up this process, such as in exercise. When exercising, the muscles work harder. Therefore, the body uses more oxygen and produces more carbon dioxide.

The skeletal muscle pump is an example of a critical mechanism that promotes blood returning to the heart during exercise. When the muscles can contract with enough force, the blood vessels are compressed in the muscle tissue. This causes blood to return to the heart. 

Circulatory System Disorders Common in Children

Circulatory disorders can occur in children. Typically, they result from improper development and can range from less severe to life-threatening. Serious congenital heart defects are typically noticed soon after birth or during the first few months of life. 

Signs and symptoms can include pale gray or blue lips, rapid breathing, swelling in the legs and other areas, and shortness of breath during feedings. There are three categories that congenital heart defects can be divided into. 

The first is altered connections in the heart or blood vessels. There are also congenital heart valve problems and a combination of heart defects. 

An example of altered connections in the heart or blood vessels would be patent ductus arteriosus. This is a connection between the lung and the body’s main artery, the aorta. It is open while the baby is in the mother’s womb. 

However, it is expected to close a few hours after birth. In some cases, it does stay open. It leads to an incorrect blood flow between the two arteries. 

There is also transposition of the great arteries, a rather complex condition that leaves the two main arteries in the heart reversed. 

It is quite rare, and there are two types: one is complete, and the other is Levo-transposition. Symptoms for the latter may not be noticed right away. 

Common Circulatory System Disorders in Adults

Circulatory system or cardiovascular diseases are rather common. They are the leading cause of death globally. 

An estimated 17.9 million people died from cardiovascular diseases in 2019; of these deaths, 85% were due to heart attack and stroke. In addition, three-quarters of these deaths occur in low and middle-income countries. 

Heart attacks occur when blood flow to the heart is reduced or severely blocked. The blockage can be due to various things, such as a buildup of fat, cholesterol, and other substances in the heart. Specifically, it blocks the coronary arteries from the heat. 


On the other hand, a stroke occurs when a blockage happens in the brain and thus impacts the blood supply. It can also happen due to a blood vessel in the brain bursting. A stroke can cause parts of the brain to be damaged or even die. 

A stroke also can lead to lasting brain damage, long-term disability, and death. Just like with a heart attack, an awareness has been developed about what to do when someone is suspected of having a stroke. 

Quick treatment is critical for stroke; therefore, calling an ambulance as soon as possible is the best course of action. 

Genetic Components of Circulatory System Disorders

Many cardiac conditions can be inherited. These included arrhythmias, congenital heart disease, cardiomyopathy, and high blood pressure. Coronary artery disease is another condition that can run in families, leading to heart attack, stroke, and heart failure. 

Genetics can influence the risk of heart disease as they can control many aspects of the cardiovascular system. This can range from the strength of the blood vessels to how cells in the heart can communicate. 

A mutation or variation in a single gene can affect the likelihood of developing heart disease. For instance, genetic mutations can alter how particular proteins work so that the body processes cholesterol differently, increasing the likelihood of blocked arteries. 

Thus, when a family member is diagnosed with heart disease or a heart disorder, other family members are strongly encouraged to undergo screening for risk factors and early-stage disease. 

Medical screening is especially encouraged for family members of a sudden cardiac death victim. If relatives of the deceased are thought to carry an inherited disorder, treatments such as drug therapies and implantable devices are available.

The more common inherited conditions include atrial fibrillation, Brugada syndrome, Long and short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia. 

Atrial fibrillation is the most common form of arrhythmia or irregular heart rhythm that can increase the risk of stroke. 

This is because it can often lead to blood clots in the heart. The first-line treatment for atrial fibrillation is a beta-blocker, which makes the heart work less to pump blood. It does so by lowering heart rate. 

How Stress Affects Cardiovascular System

Some stress levels are useful, though constant stress can influence well-being and impact heart health. Heart disease is a potential stress-related problem. This is because stress can lead to high blood pressure, characterized by blood pressure consistently greater than 140/90 mmHg. 

This can pose a risk of heart attack and stroke. Stress can contribute to cardiovascular disease risks such as smoking, overeating, and a lack of physical activity. 

According to a 2017 study in The Lancet journal, chronic stress is associated with an increased risk of cardiovascular disease

Using images of part of the brain involved with fear and stress, links were found between stress and cardiovascular disease episodes. Brain activity was studied along with bone marrow activity and artery inflammation

This is a cause for concern as two in three employees say work is a significant source of stress, according to a report from the American Heart Association Center for Workplace Health Research & Evaluation. 

Job stress can result from long working hours, physical strain, and high demand or job insecurity. Annual expenditures on work-related stress are estimated to be at $190 billion. 

While the cost of poor mental health is estimated at $211 billion annually, this number includes lost productivity and absence from work. 

How to Improve the Health of the Circulatory System

Healthy circulation allows for oxygenated blood to flow through the body. Poor circulation happens when flow is hindered or disrupted by factors that slow it down, such as plaque buildup, blood clots, or narrow blood vessels. 

Poor circulation can affect the body by leading to symptoms of pain, numbness, tingling, or cold in parts of the body with poor circulation. Typically these body parts are legs, hands, fingers, feet, and toes. Therefore, several things can be done to combat poor circulation.

Improving the health of your circulatory system is essential for overall well-being. Here are five ways to help boost your circulatory health, including yoga:

Regular Exercise

Engaging in aerobic exercises such as walking, swimming, or cycling for at least 30 minutes a day can strengthen your heart and improve circulation.

Yoga can be a great way to improve blood circulation by boosting blood flow and leading to improvement in yoga practice. The asanas, or movements, stretch the muscles and connective tissues, thus facilitating blood circulation. 

Specific asanas involve positions that expand the chest and rib cage. These allow for space to open up around the heart. Poses such as camel, wheel, bridge and dancer promote these heart openings. 

Healthy Diet

Consuming a diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats can support circulatory health. Foods that are particularly good for circulation include those high in omega-3 fatty acids, like salmon, and antioxidant-rich berries.


Drinking plenty of water is crucial for maintaining blood volume and allowing for smooth blood flow throughout your body. Aim for at least 8 glasses a day, or more if you are exercising or in a hot climate.

Quit Smoking

Smoking is a major risk factor for circulatory problems as it damages the walls of blood vessels and increases the risk of atherosclerosis. Quitting smoking can significantly improve circulatory health.

Stress Management

Chronic stress can lead to high blood pressure and heart strain. Yoga and meditation are excellent for reducing stress. Regular practice can help lower stress hormones, reduce inflammation, and improve circulation.

Incorporating these practices into your routine can lead to significant improvements in circulatory system health. 

However, it's always best to consult with a healthcare provider before starting any new health regimen, especially if you have pre-existing health conditions.


Circulatory System: Anatomy and Function

About Stroke | cdc.gov

Congenital heart defects in children - Symptoms and causes - Mayo Clinic

Poor Circulation: Symptoms, Causes and Treatment

Aerobic vs. Anaerobic Exercise: Differences & Benefits | BistroMD

Circulatory system - Wikipedia 


The contents of this article are provided for informational purposes only and are not intended to substitute for professional medical advice, diagnosis, or treatment. It is always recommended to consult with a qualified healthcare provider before making any health-related changes or if you have any questions or concerns about your health. Anahana is not liable for any errors, omissions, or consequences that may occur from using the information provided.