THE CIRCULATORY SYSTEM
The circulatory system is an organ system that passes nutrients (such as amino acids and
electrolytes), gases, hormones, blood cells, , etc. to and from cells in the body to help fight
diseases and help stabilize body temperature and pH to maintain homeostasis. This system
may be seen strictly as a blood distribution network, but some consider the circulatory
system as composed of the cardiovascular system, which distributes blood,[1] and the
lymphatic system,[2] which distributes lymph. While humans, as well as other vertebrates,
have a closed cardiovascular system (meaning that the blood never leaves the network of
arteries, veins and capillaries), some invertebrate groups have an open cardiovascular
system. The most primitive animal phyla lack circulatory system. The lymphatic system, on
the other hand, is an open system.
The main components of the human circulatory system are the heart, the blood, and the
blood vessels. The circulatory system includes: the pulmonary circulation, a "loop" through
the lungs where blood is oxygenated; and the systemic circulation, a "loop" through the rest
of the body to provide oxygenated blood. An average adult contains five to six quarts
(roughly 4.7 to 5.7 liters) of blood, which consists of plasma, red blood cells, white blood
cells, and platelets. Also, the digestive system works with the circulatory system to provide
the nutrients the system needs to keep the heart pumping.
Two types of fluids move through the circulatory system: blood and lymph. The blood,
heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and
lymph vessels form the lymphatic system. The cardiovascular system and the lymphatic
system collectively make up the circulatory system.
TYPES OF CIRCULATION
Pulmonary circulation
The pulmonary circulation is the portion of the cardiovascular system which transports
oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood
back to the heart.
Oxygen deprived blood from the vena cava enters the right atrium of the heart and flows
through the tricuspid valve into the right ventricle, from which it is pumped through the
pulmonary semilunar valve into the pulmonary arteries which go to the lungs. Pulmonary
veins return the now oxygen-rich blood to the heart, where it enters the left atrium before
flowing through the mitral valve into the left ventricle. Also, oxygen-rich blood from the left
ventricle is pumped out via the aorta, and on to the rest of the body.
Systemic circulation
Systemic circulation is the portion of the cardiovascular system which transports
oxygenated blood away from the heart, to the rest of the body, and returns oxygen-
, depleted blood back to the heart. Systemic circulation is, distance-wise, much longer than
pulmonary circulation, transporting blood to every part of the body except the lungs.
Coronary circulation
The coronary circulatory system provides a blood supply to the heart. As it provides
oxygenated blood to the heart, it is by definition a part of the systemic circulatory system.
Heart
View from the front, which means the right side of the heart is on the left of the diagram
(and vice-versa)
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the
human heart there is one atrium and one ventricle for each circulation, and with both a
systemic and a pulmonary circulation there are four chambers in total: left atrium, left
ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the
right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor
in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery
to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives
newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into
the strong left ventricle to be pumped through the aorta to the tissues of the body.
Closed cardiovascular system
The cardiovascular systems of humans are closed, meaning that the blood never leaves the
network of blood vessels. In contrast, oxygen and nutrients diffuse across the blood vessel
layers and enters interstitial fluid, which carries oxygen and nutrients to the target cells,
and carbon dioxide and wastes in the opposite direction. The other component of the
circulatory system, the lymphatic system, is not closed.
The circulatory system is an organ system that passes nutrients (such as amino acids and
electrolytes), gases, hormones, blood cells, , etc. to and from cells in the body to help fight
diseases and help stabilize body temperature and pH to maintain homeostasis. This system
may be seen strictly as a blood distribution network, but some consider the circulatory
system as composed of the cardiovascular system, which distributes blood,[1] and the
lymphatic system,[2] which distributes lymph. While humans, as well as other vertebrates,
have a closed cardiovascular system (meaning that the blood never leaves the network of
arteries, veins and capillaries), some invertebrate groups have an open cardiovascular
system. The most primitive animal phyla lack circulatory system. The lymphatic system, on
the other hand, is an open system.
The main components of the human circulatory system are the heart, the blood, and the
blood vessels. The circulatory system includes: the pulmonary circulation, a "loop" through
the lungs where blood is oxygenated; and the systemic circulation, a "loop" through the rest
of the body to provide oxygenated blood. An average adult contains five to six quarts
(roughly 4.7 to 5.7 liters) of blood, which consists of plasma, red blood cells, white blood
cells, and platelets. Also, the digestive system works with the circulatory system to provide
the nutrients the system needs to keep the heart pumping.
Two types of fluids move through the circulatory system: blood and lymph. The blood,
heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and
lymph vessels form the lymphatic system. The cardiovascular system and the lymphatic
system collectively make up the circulatory system.
TYPES OF CIRCULATION
Pulmonary circulation
The pulmonary circulation is the portion of the cardiovascular system which transports
oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood
back to the heart.
Oxygen deprived blood from the vena cava enters the right atrium of the heart and flows
through the tricuspid valve into the right ventricle, from which it is pumped through the
pulmonary semilunar valve into the pulmonary arteries which go to the lungs. Pulmonary
veins return the now oxygen-rich blood to the heart, where it enters the left atrium before
flowing through the mitral valve into the left ventricle. Also, oxygen-rich blood from the left
ventricle is pumped out via the aorta, and on to the rest of the body.
Systemic circulation
Systemic circulation is the portion of the cardiovascular system which transports
oxygenated blood away from the heart, to the rest of the body, and returns oxygen-
, depleted blood back to the heart. Systemic circulation is, distance-wise, much longer than
pulmonary circulation, transporting blood to every part of the body except the lungs.
Coronary circulation
The coronary circulatory system provides a blood supply to the heart. As it provides
oxygenated blood to the heart, it is by definition a part of the systemic circulatory system.
Heart
View from the front, which means the right side of the heart is on the left of the diagram
(and vice-versa)
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the
human heart there is one atrium and one ventricle for each circulation, and with both a
systemic and a pulmonary circulation there are four chambers in total: left atrium, left
ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the
right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor
in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery
to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives
newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into
the strong left ventricle to be pumped through the aorta to the tissues of the body.
Closed cardiovascular system
The cardiovascular systems of humans are closed, meaning that the blood never leaves the
network of blood vessels. In contrast, oxygen and nutrients diffuse across the blood vessel
layers and enters interstitial fluid, which carries oxygen and nutrients to the target cells,
and carbon dioxide and wastes in the opposite direction. The other component of the
circulatory system, the lymphatic system, is not closed.
