The heart is a muscular organ located in the chest between the lungs. It pumps blood through the circulatory system, supplying oxygen and nutrients to tissues and removing waste. The heart has four chambers - two upper atria and two lower ventricles - separated by valves that ensure blood flows in only one direction. It works continuously to circulate blood through two circuits: the pulmonary circuit through the lungs and systemic circuit through the body. Valves between the chambers prevent backflow of blood as it is pumped from the atria to ventricles and out of the heart.

2. Introduction
The heart is a muscular organ in humans and
other animals too. The work of this heart is to
pump the blood through the blood vessels of
the circulatory system. This blood provides
oxygen to the body and removes metabolic
wastes. It is located in between the lungs an
the middle compartment of the chest.
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3. Location
The heart is located in
between the lungs an the
middle compartment of the
chest. Heart is typically the
size of a fist
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4. Importance of Heart
Heart is to pump the blood
through the blood vessels of
the circulatory system. This
blood provides oxygen to the
body and removes metabolic
wastes. It is located in
between the lungs an the
middle compartment of the
chest.
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5. Functions of Heart
Main functions of the heart can be
summarised as follows :
• Right - Hand Side of the Heart
Right hand side of the heart receives
de-oxygenated blood from the body
tissues into the right atrium.
• Left - Hand Side of the Heart
Left-hand side of the heart receives
oxygenated blood from the lungs into
the left atrium.
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6. Working
In humans, mammals and birds are divided into four
chambers. They are upper left and right atria and lower
left and right ventricles. Commonly the right atrium and
ventricles are referred together as the right heart and
their left counter parts as the left heart. Fish in contrast
have two chambers on atrium and a ventricle, while the
reptiles have three chambers. In a active heart blood
flows one way through the heart due to heart valves,
which prevent the back flow.
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7. The heart is enclosed in a protective
sack, the pericardium, which also
contains a small amount of fluid. The
valve of the heart is made up of
three layers they are epicardium,
myocardium and endocardium. The
heart pumps blood with a rhythm
determined by a group of pace
making cells in the Sino atrial node.
It generate a current that causes
contraction of the heart, travelling
through the atrio ventricular node
and along the conduction system of
the heart.
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8. Blood flow
The heart receives blood flow in oxygen
from the systemic circulation, which enters
the right atrium from the superior and
inferior vena cavae and passes to the right
ventricle. It is pumped into the pulmonary
of circulation, and then through the lungs
and where it receives oxygen and gives of
carbon dioxide. The heart has four valves
which separate its chambers. One valve
lies between each atrium and ventricle,
and one valve rests at the exit of each
ventricle. The valves between atria and
ventricles are called the atrio ventricular
valves.
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9. Between the right atrium and the right ventricle is the tricuspid valve. The
tricuspid valve has three cups, which connect to chordae tendinae and
three papillary muscles named the anterior, posterior, and septal muscles,
after their relative positions. The mitral valve lies between the left atrium
and left ventricle. It is also known as the bicuspid valve.
The papillary muscles extend from the walls of the heart to valves
by cartiligagenous connections called cadre tendinae. These muscles
prevent the valves from falling too far back when they close. During the
relaxation phase of the cardiac cycle, the papillary muscles are also
relaxed and the tension on the cadre tendineae is slight. As the heart
chambers contact, so do the papillary muscles. This creates tension in the
cardae tendineae.
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10. Advantages
Pumps the blood
Transports the blood to every part of the body.
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11. Disadvantages
Cannot be replaced
Very sensitive part.
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