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 vessels
    • Control of blood vessel diameter
    • Blood supply
    • Internal respiration
    • Cell nutrition
  • Heart
    • Position
    • Structure
    • Flow of blood through the heart
    • Blood supply to the heart
    • Conducting system of the heart
    • The cardiac cycle
    • Cardiac output
  • Blood pressure
    • Control of blood pressure (BP)
  • Pulse
  • Circulation of the blood
    • Pulmonary circulation
    • Systemic or general circulation
      • Aorta
      • Portal circulation
  • Summary of the main blood vessels
  • Shock
  • Diseases of blood vessels
    • Atheroma
    • Arteriosclerosis
    • Thromboangiitis obliterans (Buerger’s disease)
    • Polyarteritis nodosa
    • Aneurysms
    • Venous thrombosis
    • Varicose veins
    • Tumors of blood and lymph vessels
  • Thrombosis, embolism and infarction
  • Odema
    • Ascites and effusions
  • Diseases of the heart
    • Cardiac failure
      • Right-sided (congestive) cardiac failure
      • Left-sided or left ventricular failure
    • Disorders of heart valves
    • Ischemic heart disease
      • Angina pectoris
      • Myocardial infarction
    • Rheumatic heart disease
      • Rheumatic fever
    • Infective endocarditis
      • Acute infective endocarditis
      • Subacute infective endocarditis
    • Cardiac arrythmias
      • Asystole
      • Fibrillation
      • Heart block
    • Congenital abnormalities
      • Patent ductus arteriosus
      • Atrial septal defect
      • Coarctation of the aorta
      • Fallot’s tetralogy
  • Disorders of blood pressure
    • Hypertension
      • Essential hypertension
      • Secondary hypertension
      • Pulmonary hypertension
    • Hypotension