Heart, the human pumping beast
Heart, the human pumping beast obrnB
The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system. [1] The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. [2] In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest. [3]
In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. [4][5] Commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. [6] Fish, in contrast, have two chambers, an atrium and a ventricle, while reptiles have three chambers. [5] In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. [3] The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium. [7]
The
heart
is a muscular organ in most animals, which pumps
blood
through the
blood
vessels of the circulatory system. [1] The pumped
blood
carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. [2] In humans, the
heart
is approximately the size of a closed fist and
is located
between the lungs, in the middle compartment of the chest. [3]
In humans, other mammals, and birds, the
heart
is divided
into four chambers: upper
left
and
right
atria and lower
left
and
right
ventricles. [4][5]
Commonly
the
right
atrium and ventricle
are referred
together as the
right
heart
and their
left
counterparts as the
left
heart
. [6] Fish,
in contrast
, have two chambers, an atrium and a ventricle, while reptiles have three chambers. [5] In a healthy
heart
blood
flows one way through the
heart
due to
heart
valves, which
prevent
backflow. [3] The
heart
is enclosed
in a protective sac, the pericardium, which
also
contains a
small
amount of fluid. The wall of the
heart
is made
up of three layers:
epicardium
, myocardium, and
endocardium
. [7]