Video Transcript
What type of body tissue are the
walls of the heart primarily comprised of? (A) Epithelial, (B) nervous, (C)
muscle, or (D) skeletal.
This question is asking about the
main tissue making up the heart. So let’s review the key facts about
the structure and tissues of the heart to answer the question correctly.
The heart is a muscular organ,
which is part of the cardiovascular system. The type of muscle it is made of is
called cardiac muscle, cardiac referring to the heart. This muscle can keep contracting
without tiring, which is important as we rely on it to keep us alive. The heart is located in the chest
between the lungs, and it is responsible for pumping blood all around the body. Amongst other things, the blood
carries oxygen and nutrients to the cells and also removes wastes. In order to deliver these
substances quickly enough for the cells’ needs, the heart has a specialized
structure to make sure it pumps the blood as efficiently as possible. So let’s have a look at this in
more detail.
The heart is made up of four main
types of tissue: muscular, nervous, epithelial, and connective. We can use this diagram to explain
where the tissues are found and understand more about the structure. As you can see, the heart is
divided into two halves by the septum down the middle. Then, each side is divided into two
chambers — the upper atria, or atrium if talking about one, and the lower
ventricles. These chambers are lined by
epithelial cells, which also make up part of the outer layer of the heart. The atria collect the blood as it
enters the heart via the veins. Both atria contract together to
pump the blood into the ventricles, which then contract together to pump the blood
out of the heart.
As you can see, the left ventricle
has a thicker muscular wall than the right, as it has to pump blood under high
pressure all around the body. The right ventricle only has to
pump the blood to the lungs. And if the pressure was too high,
it would damage the delicate capillaries found in the lungs. The atria and ventricles have
valves between them which are mainly made up of connective tissue. These allow the blood to flow from
the atria into the ventricles, but not back again. These are one of the structures to
increase the efficiency of the heart by making sure the blood only travels in one
direction.
Contraction of the muscle of the
heart is controlled by an area of nervous tissue, which you may have heard called
the pacemaker. This is found in the wall of the
right atrium. And its signal is transmitted
across the heart to make sure that it beats rhythmically.
Having reviewed these facts about
the structure of the heart, let us return to the question. It is asking for the main tissue of
this organ. We have learnt that there is
epithelial tissue lining and covering the heart and that nervous tissue regulates
the beating of it. But you can see from the diagram
that the majority of the heart is made up of the special tissue, cardiac muscle.
The correct answer is therefore
(C). The type of body tissue that the
walls of the heart are primarily comprised of is muscle.
