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Introduction to the Cardiovascular System

Description of the cardiovascular system

The cardiovascular system, also known as the circulatory system, is one of the eleven major organ systems in the human body. It is arguably the most important organ system in the human body, as the heart and blood vessels are located to circulate blood, oxygen, and nutrients throughout our body.

Diagram of the circulatory system showing the path blood takes from the body to the lungs and back, with color-coded routes for oxygen-poor blood in blue and oxygen-rich blood in red. The diagram includes a detailed illustration of the heart and a human figure with labeled blood vessels.

Key Parts/Organs:

Heart -

The heart is the main organ of the cardiovascular system. The heart consists of different structures like chambers and valves.

Function: Controls the rhythm and speed of the heart rate and maintains the blood pressure. It works with other organ systems such as the nervous and endocrine system to control the speed of the heart rate.

Chambers -

The chambers are structures of the heart to manage the heartbeat and blood flow throughout the body. The heart consists of 4 chambers: right atrium, right ventricle, left atrium, left ventricle.

Function: Chambers are used to help recirculate blood by pumping the deoxygenated blood to the lung and pumping oxygenated blood to throughout the body.

Valves -

The valves are made of flaps of tissues called leaflets and are located between the chambers. The heart consists of 4 types of valves: tricuspid, pulmonary, mitral, aortic. The tricuspid, pulmonary, and aortic valves have three leaflets whereas the mitral valve only has two leaflets.

Function: Valves manage the blood flow by opening and closing to help blood flow through the chambers and then throughout the body.

Blood Vessels -

Blood vessels help circulate blood throughout the body and are connected to the heart. There are three main types of blood vessels: arteries, veins, capillaries.

Function of arteries: Arteries carry oxygenated blood from the heart to the body.

Function of veins: Veins carry the deoxygenated blood to the heart, which the chambers will pump the blood to the lungs to get re-oxygenated.

Function of capillaries: Capillaries attach the arteries and veins and are used to transfer oxygen, nutrients, and waste.

Diagram of the four heart chambers with labels, showing oxygen-poor blood in blue and oxygen-rich blood in red. The four chambers are right atrium, right ventricle, left atrium, and left ventricle, with the heart's structure and blood flow pathways depicted.
Labelled diagram of the inside of a human heart showing the aorta, pulmonary trunk, aortic valve, left atrium, bicuspid (mitral) valve, left ventricle, ventricular septum, left ventricle, pulmonary valve, right ventricle, tricuspid valve, inferior vena cava, right atrium, superior vena cava.
Diagram of the human heart showing the right and left atria, right and left ventricles, aorta, pulmonary artery, pulmonary vein, superior and inferior vena cava, and valves including the mitral, aortic, pulmonary, and tricuspid valves.
Diagram of the human circulatory system showing blood vessels, including lungs, heart, vena cava, and aorta. An inset explains blood vessel types with labels for artery, arteriole, capillaries, venule, and vein.

Sources and Images Citation:

National Cancer Institute . “NCI Dictionary of Cancer Terms.” National Cancer Institute, Cancer.gov, 2019, www.cancer.gov/publications/dictionaries/cancer-terms/def/circulatory-system.

Cleveland Clinic. “Heart: Anatomy and Function.” Cleveland Clinic, Cleveland Clinic, 26 Jan. 2024, my.clevelandclinic.org/health/body/21704-heart.

Cleveland Clinic. “Chambers of the Heart.” Cleveland Clinic, Cleveland Clinic, 20 May 2022, my.clevelandclinic.org/health/body/23074-heart-chambers.

Cleveland Clinic. “4 Heart Valves: What They Are and How They Work.” Cleveland Clinic, 2022, my.clevelandclinic.org/health/body/17067-heart-valves.

Cleveland Clinic. “Blood Vessels.” Cleveland Clinic, 9 July 2021, my.clevelandclinic.org/health/body/21640-blood-vessels.

Images from Cleveland Clinic, CC BY-SA 4.0.

Valve Image from Wikimedia Common, CC BY-SA 4.0.

Published on June 17, 2025

Introduction to the Cardiovascular System