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The Heart
By: Emma, Miki, Álvaro &
María
1. What is the heart?

The human heart is a muscular organ
that provides a continuous blood
circulation through the cardiac cycle
and is one of the most vital organs in
the human body.
3. The structure of the heart.
 It is enclosed in a double-walled sac called the

pericardium. The outer wall of the human heart is
composed of three layers. The outer layer is called
the epicarduim. The middle layer is called the
myocardium and is composed of muscle which
contracts. The inner layer is called the endocardium
and is in contact with the blood that the heart pumps.
It has four cavities, two superior atria and two
inferior ventricles. The atria are the receiving
cavities and the ventricles are the discharging
cavities.
3. Functioning

Blood without oxygen flows through the heart in one
direction, entering through the superior vena cava
into the right atrium and is pumped through the
tricuspid valve into the right ventricle before being
pumped out through the pulmonary valve to the
pulmonary arteries into the lungs. It returns from
the lungs through the pulmonary veins to the left
atrium where it is pumped through the mitral valve
into the left ventricle before leaving through the
aortic valve to the aorta.
Functioning 2
 The function of the right side of the heart is to

collect blood without oxygen, in the right atrium,
from the body, and pump it, by the right ventricle, to
the lungs.
The left side of the heart is in charge of collecting
blood with oxygen from the lungs into the left atrium.
From the left atrium the blood moves to the left
ventricle which pumps it out to the body through the
aorta.
4. Picture of the heart.
5. Some facts.

The human heart has a mass of between 250 and 350 grams and is
about the size of a fist. It is located between the vertebal column and
the sternum.

The adult heart pumps 9120 liters of blood each day.

Blood is about 78% water.

Blood takes about 20 seconds to circulate throughout the entire
vascular system.

Most heart attacks accur between the hours of 8 and 9 of the morning.

The human heart can create enough pressure that it could squirt blood
at a distance of ten metres.
6. Why blood is red?


Red blood cells, encased in blood vessels, color the
blood. Since there are about 35 trillion of these tiny,
round, flat discs circulating in one's body at any one
time, their sheer number necessarily lends their red
color to the blood.
Red blood cells have a life expectancy of
approximately four months, before they are broken
up, primarily in the spleen, and are replaced by new
red blood cells. New cells are continuously generated
to replace the old cells that have past their prime,
and have been destroyed to make room for the
younger generation.
7. Bibliography
 www.wikipedia.com
- Structure.
- Functioning.
– The Heart
www.interestingfacts.com
 www.coolquiz.com
 www.youtube.com
– The Circulatory Song.

THE END
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