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Answers
Answer:
Heart is present almost at centre in
thoracic cage. It is present behind the
ribs, between two lungs and slightly
inclined on left side.
Size of our heart is equal to one's
own fist and its weight is about 360
gram. It is covered by a double layered
peritoneal membrane. A fluid is present
between two membranes due to which
heart is protected from friction and
mechanical shocks.
Human heart is a muscular organ.
It is made up of involuntary cardiac
muscles. They contract and relax with a
definite rhythm. This is called as beating
of heart.
Internally, heart is divided into left
and right compartments by a vertical
partition. Each of those compartments
is again divided into two chambers.
Thus, in all, heart consists of four
chambers. Upper chambers are called
as atria (singular - atrium) and lower
chambers as ventricles