The Circulatory System 

A flow chart, like this one, shows how a process begins and ends, and the steps in between.

The process can be of almost any kind, from manufacturing a tire to creating an advertisement.

Therefore, learning how to describe and explain a process in English is important.

It's important for teachers, engineers, and people who provide customer support.

One process that we are all familiar with is our body's circulatory system.

This system provides oxygen throughout the body and eliminates carbon dioxide, which is a waste product.

If something goes wrong with this system, we need to repair it quickly, or we die.

So it's important to understand it and keep it functioning properly.

What does the circulatory system do?It provides oxygen to the body and eliminates carbon dioxide.

It provides oxygen to the body and eliminates carbon dioxide.

It’s important to keep it functioning properly, or we will die.

First, the most important requirement for the system to work is a supply of air.

Without fresh air with sufficient oxygen, the process won't keep us healthy and alive.

So the process begins by breathing in air, which happens when the lungs expand and draw in air.

Once inside the lungs, oxygen in the air is exchanged for carbon dioxide in the blood.

This exchange happens when blood cells release carbon dioxide and absorb oxygen.

This blood is now oxygenated blood, which means it carries oxygen.

What kind of air is require to keep us healthy and alive? fresh air with sufficient oxygen

To summarize, the process begins by inhaling air and oxygenating the blood.

The oxygenated blood in the lungs then flows back to the heart.

The C02 which came from the blood is exhaled, and the next cycle begins? 

Where does the oxygenated blood go?back to the heart

To stay healthy and alive, we need fresh air with sufficient oxygen.

This happens when the lungs contract.

Note that the blood in the lungs flows in a loop from the heart.

The blood which enters the loop from the heart carries carbon dioxide.

Once the carbon dioxide is exchanged for oxygen, the blood continues through the loop and exits into the heart.

The oxygenated blood is then pumped to the rest of the body.

What happens to the oxygenated blood after flows to the heart ? it's pumped to the rest of the body

As you can see, everything depends on the flow of blood to and from the heart.

So how does the heart do this?

First, the heart, which is a muscle, has 4 chambers.

From one chamber, blood is pumped to the lungs.

This is the blood that carries carbon dioxide.

When the oxygenated blood from the lungs comes back to the heart, it enters another chamber.

This chamber is called the left atrium.

What does the blood pump to the lungs carry? it carries CO2

From the left atrium, the oxygenated blood is pumped into another chamber, the left ventricle.

The left ventricle then pumps the blood into the aorta, which is the largest artery in the body.

From the aorta, the oxygenated blood passes through a network of smaller  arteries throughout the entire body, including the brain.

Blood returns to the heart through a system of veins and enters the upper right  chamber, the right atrium.

Now that we understand a little about the circulatory system we can ask what it needs to operate.

Of course it can't operate without energy.

This energy is supplied by another system, the digestive system, which gets energy from food.

And of course these systems need to be supported and controlled.

Our skeletal system provides support, and our muscular system provides control and movement.

Without support and movement, we couldn't get the food that we need for energy.

Only plants can do this because they have a completely different system, which gets energy directly from the sun.

What life forms get energy directly from the sun? plants

To summarize, the human body is like a huge, complex factory.

The language we use to describe how it functions is the same language we use to describe almost any industrial process.

The vocabulary is different, but the processes, flows and logical relationships are almost identical.

Think of some familiar process in your life or job and see if you can describe and explain it in English.

Plants get energy directly from the sun by using photosynthesis.