Cardiovascular System

The cardiovascular system is an organ system that permits blood to circulate and transport nutrients, oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homoeostasis.

It is divided into two main parts:

Heart: The heart is a muscular organ which pumps blood through the blood vessels of the circulatory system.

Blood vessels: Blood vessels transport blood throughout the human body. There are three major types of blood vessels: arteries (carry blood away from the heart), capillaries (enable exchange of water and chemicals between the blood and the tissues) and veins (carry blood from the capillaries back toward the heart).

The lymphatic system is connected with the cardiovascular system both structurally and functionally.


The cardiovascular system has two distinct circulatory paths:

  • Pulmonary circulation
  • Systemic circulation

The right side of the heart pumps blood to the lungs (pulmonary circulation). In the lungs blood gets oxygenated from the air sacs. At the same time, carbon dioxide diffuses into the air sacs and is exhaled into the atmosphere.

The left side of the heart pumps blood into the systemic circulation which supplies to the rest of the body. In the tissues, blood releases oxygen and nutrients and collects carbon dioxide and wastes.

The cardiovascular system continuously pumps blood to all parts of the body. Its functioning is regulated continuously to maintain adequate blood supply. In the absence of adequate blood supply, tissue damage and cell death will result.

Cardiovascular function declines with age. Diseases affecting the cardiovascular system are called cardiovascular disease.

Topics in this section

Blood vesselsArteries and arteriolesCapillaries and sinusoids
Veins and venulesControl of blood vessel diameterCapillary exchange
The heartStructure of the heartFlow of blood through the heart
Blood supply to the heart (Coronary circulation)Electrical conduction system of the heartFactors affecting heart rate
Cardiac cycleHeart soundsElectrical changes in the heart during cardiac cycle
Cardiac OutputFactors Affecting Stroke VolumeFactors Affecting Cardiac Output
Blood pressureFactors determining blood pressureControl of blood pressure
PulseCirculation of BloodPulmonary circulation
Systemic or General Circulation Major blood vesselsVena Cavae
Circulation in the head and neckCirculation in the upper limbCirculation in the thorax
Circulation in the abdomenHepatic portal systemCirculation in the pelvis and lower limb
Fetal circulationAging and the cardiovascular systemShock
Thrombosis and ischemia