Cardiovascular System

Cardiovascular System

The cardiovascular system is responsible for transporting nutrients and removing gaseous waste from the body. This system is comprised of the heart and the circulatory system. Structures of the cardiovascular system include the heart, blood vessels, and blood. The lymphatic system is also closely associated with the cardiovascular system.

Structures of the Cardiovascular System

The cardiovascular system circulates oxygen and nutrients throughout the body. PIXOLOGICSTUDIO/Science Photo Library/Getty Images


The heart is the organ that supplies blood and oxygen to all parts of the body. This amazing muscle produces electrical impulses through a process called cardiac conduction. These impulses cause the heart to contract and then relax, producing what is known as a heart beat. The beating of the heart drives the cardiac cycle which pumps blood to cells and tissues of the body.

Blood Vessels

Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body. Blood travels from the heart via arteries to smaller arterioles, then to capillaries or sinusoids, to venules, to veins and back to the heart. Through the process of microcirculation, substances such as oxygen, carbon dioxide, nutrients, and wastes are exchanged between the blood and the fluid that surrounds cells.


Blood delivers nutrients to cells and removes wastes that are produced during cellular processes, such as cellular respiration. Blood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells contain enormous amounts of a protein called hemoglobin. This iron-containing molecule binds oxygen as oxygen molecules enter blood vessels in the lungs and transports them to various parts of the body. After depositing oxygen to tissue and cells, red blood cells pick up carbon dioxide (CO2) for transportation to the lungs where CO2 is expelled from the body.

Circulatory System

The circulatory system supplies the body's tissues with oxygen-rich blood and important nutrients. In addition to removing gaseous waste (like CO2), the circulatory system also transports blood to organs (such as the liver and kidneys) to remove harmful substances. This system aids in cell-to-cell communication and homeostasis by transporting hormones and signal messages between the different cells and organ systems of the body. The circulatory system transports blood along pulmonary and systemic circuits. The pulmonary circuit involves the path of circulation between the heart and the lungs. The systemic circuit involves the path of circulation between the heart and the rest of the body. The aorta distributes oxygen rich blood to the various regions of the body.

Lymphatic System

The lymphatic system is a component of the immune system and works closely with the cardiovascular system. The lymphatic system is a vascular network of tubules and ducts that collect, filter, and return lymph to blood circulation. Lymph is a clear fluid that comes from blood plasma, which exits blood vessels at capillary beds. This fluid becomes the interstitial fluid that bathes tissues and helps to deliver nutrients and oxygen to cells. In addition to returning lymph to circulation, lymphatic structures also filter blood of microorganisms, such as bacteria and viruses. Lymphatic structures also remove cellular debris, cancerous cells, and waste from the blood. Once filtered, the blood is returned to the circulatory system.

Cardiovascular Disease

Colored Scanning Electron Micrograph (SEM) of a longitudinal section through a human coronary artery of the heart showing atherosclerosis. Atherosclerosis is the build-up of fatty plaques on the walls of arteries. Here, the artery wall is brown with inner lumen blue. Fatty plaque known as atheroma (yellow) has built-up on the inner wall, and is blocking about 60% of the artery width. Atherosclerosis leads to irregular blood flow and clot formation, which can block the coronary artery resulting in heart attack. Professor P.M. Motta, G. Macchiarelli, S.A Nottola/Science Photo Library/Getty Images

According to the World Health Organization, cardiovascular disease is the leading cause of death for people world-wide. Cardiovascular disease involves disorders of the heart and blood vessels, such as coronary heart disease, cerebrovascular disease (stroke), elevated blood pressure (hypertension), and heart failure.

  • Hypertension: persistently elevated blood pressure (high blood pressure) in the arteries. It is associated with the development of disorders such as atherosclerosis, heart attack, and stroke, and can cause kidney damage.
  • Atherosclerosis: artery walls become hardened due to build up of plaque (fatty deposits). It causes decreased blood supply to tissues and may lead to blood clots, stroke, aneurysm, or heart disease.
  • Aneurysm: a bulging in a weakened area of an artery that could rupture and cause internal bleeding.
  • Coronary artery disease (heart disease): narrowing or blockage in the coronary arteries, which supply blood directly to the heart muscle. Complete blockage of blood flow will cause a heart attack.
  • Stroke: death of brain cells (neurons) due to lack of blood supply.
  • Heart failure: the heart is not able to supply enough blood to body tissues. It is caused by conditions such as hypertension, heart disease, and cardiomyopathy (chronic disease of the heart muscle).

It is crucial that the organs and tissues of the body receive proper blood supply. Lack of oxygen means death, therefore having a healthy cardiovascular system is vital for life. In most cases, cardiovascular disease can be prevented or greatly diminished through behavioral modifications. Individuals wishing to improve cardiovascular health should consume a healthy diet, exercise regularly, and abstain from smoking.