Video Transcript
In the human heart, why is the wall
of the left ventricle thicker than that of the right ventricle? Option (A) the left ventricle is
adapted to push blood at high pressure to the lungs. Option (B) the left ventricle is
adapted to push blood at high pressure around the body. Option (C) the right ventricle only
stores the blood it receives from the body and does not need to push it out of the
heart. Or option (D) the right ventricle
is adapted to push blood at low pressure around the body.
Your heart is vital to keeping you
alive. It pumps blood full of nutrients,
gases, chemical messengers, and more throughout all of your body. It is made of special muscle tissue
called cardiac muscle tissue. Let’s look at the diagram of the
heart.
First, note that when we talk about
the left side of the heart, we show what happens on the right of the diagram. And when we talk about the right
side of the heart, we show what happens on the left of the diagram. This is because we draw it as if we
are looking at the heart of a person standing in front of us.
Let’s review the structure of the
heart. Numbers one and two refer to the
right and left atria, or singular atrium. These are the chambers of the heart
that receive blood from veins. Blood is then pumped from the atria
to the ventricles. The left ventricle is labeled as a
three and the right ventricle as a four in this diagram.
Let’s now consider the right side
of the heart specifically. The vena cava is a vein numbered as
five, which delivers deoxygenated blood to the right atrium from the rest of the
body. Deoxygenated blood is represented
as blue in our diagram. This deoxygenated blood then leaves
the heart through the pulmonary artery, numbered as six. From there, the blood flows to the
lungs to become oxygenated.
Now let’s look at the left side of
the heart. The pulmonary vein, labeled as
seven, delivers oxygenated blood from the lungs to the left atrium. Oxygenated blood is represented
here in red. The oxygenated blood will then
leave the heart through the aorta, labeled as eight, to be delivered to the rest of
the body.
The diagram shows a simplified
version of the human double circulatory system. The circuit of blood flowing from
the aorta through the body and back to the heart via the vena cava is called the
systemic circuit, whereas the circuit in which the blood flows from the pulmonary
artery to the lungs and back to the heart through the pulmonary vein is called the
pulmonary circuit.
Since the blood in the systemic
circuit must travel all the way throughout the body, it needs to leave the heart at
a higher pressure. In contrast, the blood coming from
the right side of the heart only has to travel to the lungs. This is the reason why the wall of
the left ventricle is typically thicker than that of the right ventricle. It needs more muscular force to
contract to push the blood out under high pressure.
We now know that the correct answer
to our question is (B). The left ventricle is adapted to
push blood at high pressure around the body.
