The circulatory system, also known as the cardiovascular system, circulates blood to transport nutrients, oxygen, and hormones while maintaining homeostasis. It comprises the heart, blood, and blood vessels, including pulmonary and systemic circulation, with arteries carrying oxygenated blood away from the heart and veins returning deoxygenated blood. Proper circulation is essential for overall health, as poor blood flow can lead to serious medical conditions like blood clots and heart disease.

1. Blood, Heart and
Circulation

4. The circulatory system, also called the
cardiovascular system or the vascular
system, is an organ system that
permits blood to circulate and
transport nutrients (such as amino
acids and electrolytes), 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 homeostasis. The study of the blood
flow is called hemodynamics. The study of
the properties of the blood flow is
called hemorheology.

6.  The essential components of the human
cardiovascular system are
the heart, blood and blood vessels. It
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, accounting for
approximately 7% of their total body
weight.

7. Relative
percentages of
cardiac output
delivered to
major organ
systems

9. Arteries are blood vessels that carry blood away from the
heart.. The effective arterial blood volume is that extracellular
fluid which fills the arterial system. Arteries form part of
the circulatory system. They carry blood that is oxygenated
after it has been pumped from the heart. Arteries also aid the
heart in pumping blood. Arteries carry oxygenated blood away
from the heart to the tissues, except for pulmonary arteries,
which carry blood to the lungs for oxygenation. There are
two unique arteries. The pulmonary artery carries blood from
the heart to the lungs, where it receives oxygen. It is unique
because the blood in it is not "oxygenated", as it has not yet
passed through the lungs. The other unique artery is
the umbilical artery, which carries deoxygenated blood from a
fetus to its mother.
Arteries

11. Veins
Veins are blood vessels that carry blood toward
the heart. Most veins carry deoxygenated blood
from the tissues back to the heart; exceptions are
the pulmonary and umbilical veins, both of which
carry oxygenated blood to the heart. In contrast to
veins, arteries carry blood away from the heart.
Veins are less muscular than arteries and are often
closer to the skin. There are valves in most veins to
prevent backflow. The largest veins in the human
body are the venae cavae. These are two large
veins which enter the right atrium of the heart from
above and below.

14. Heart
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 different
organs of the body.

16. The circulatory system of the lungs is the portion of the
cardiovascular system in which oxygen-depleted blood is
pumped away from the heart, via the pulmonary artery, to
the lungs and returned, oxygenated, to the heart via
the pulmonary vein.
Oxygen deprived blood from the superior and inferior vena
cava enters the right atrium of the heart and flows through
the tricuspid valve (right atrio-ventricular valve) into the right
ventricle, from which it is then pumped through the pulmonary
semilunar valve into the pulmonary artery to the lungs. Gas
exchange occurs in the lungs, whereby CO2 is released from
the blood, and oxygen is absorbed. The pulmonary vein
returns the now oxygen-rich blood to the left atrium.
A separate system known as the bronchial circulation supplies
blood to the tissue of the larger airways of the lung.
lungs

18. How circulatory system works????
Blood circulation starts when the heart relaxes between
two heartbeats: blood flows from both atria (the upper
two chambers of the heart) into the ventricles (the lower
two chambers) which then expand. The following phase
is called ejection period, which is when both ventricles
pump the blood into the large arteries. In the systemic
circulation, the left ventricle pumps oxygen-
rich blood into the main artery (aorta). The blood travels
from the main artery to larger and smaller arteries into
the capillary network. There the blood releases
oxygen, nutrients and other important substances and
takes on carbon dioxide and waste substances. The
blood, which is now low in oxygen, is now collected
in veins and travels to the right atrium and into the right
ventricle.

19. Now pulmonary circulation starts: The right ventricle
pumps blood that carries little oxygen into
the pulmonary artery, which branches off into
smaller and smaller arteries and capillaries. The
capillaries form a fine network around the
pulmonary vesicles, grape-like air sacs at the end of
the airways. This is where carbon dioxide is released
from the blood into the air contained in the
pulmonary vesicles and fresh oxygen enters the
bloodstream. When we breathe out, carbon dioxide
leaves our body. Oxygen-rich blood travels through
the pulmonary vein and the left atrium into the left
ventricle. The next heart beat starts a new cycle
of systemic circulation.

23. Causes of poor blood circulation
Eating too much junk food which usually leads to being
overweight is also a prime reason. Work related issues,
such as sitting too long at a computer for years can cause
these problems. Especially if you don't take regular breaks
or exercise a few times a week There are several medical
conditions that slow down or block blood circulation . One
of the most dangerous is formation of a blood clot. A
blood clot will stop or inhibit blood flow from one part of
your body to the remaining areas, causing a stroke or
severe damage to your arteries. Other causes of poor
blood circulation include Raynaud's Disease, where
arteries that supply oxygen-rich blood narrow; heart
disease; and deep vein thrombosis..

24. Benefits of proper circulation…
Having an increase in blood flow and
circulation to areas of your body helps
promote cell growth and organ function.
Your skin also benefits from an increase in
blood circulation. Healthy skin is better
able to fight off bacteria and infection that
it may come in contact with. When your
heart pumps at full force, your heart rate
lowers, heart muscles relax and your blood
pressure flows evenly and smoothly.