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Compare Features of the Circulatory System

Worksheet Overview

QUESTION 1 of 10

Did you know that your heart beats about 100,000 times a day?! And that it sends about 2,000 gallons of blood around your body?! That’s around the same amount as 16,000 pints of milk!

The cells in our body need a good supply of oxygen and nutrients.  They also need to get rid of waste substances. Our blood carries out both of these functions. The circulatory system consists of blood vessels such as arteries, veins and capillaries and a pump called the heart.

 

Image of the circulatory system

 

 

Blood passes through the heart twice on every full circuit of the body. This is called a double circulatory system. A double circulatory system separates the blood with oxygen from the blood without oxygen. Blood with oxygen is called oxygenated blood. Blood without oxygen is called deoxygenated blood. 

There are two circuits, the systemic circuit and pulmonary circuit. The pulmonary circuit is where blood is transported to and from the lungs, by the heart, whereas the systemic circuit is where blood is transported to the rest of the body.

Each organ of the body is supplied with blood from its own artery.  This blood is oxygenated. Deoxygenated blood is taken away from organs by veins. 

When blood has been pumped out of the left ventricle of the heart, it begins to make its journey around the body in an artery called the aorta.  The blood is rich in oxygen. Oxygen is carried by red blood cells. The oxygen leaves the red blood cells as they pass through the capillaries.  Capillaries are the network of blood vessels which pass in between the cells in the body. As blood leaves the capillaries, it enters veins. Veins return blood to the heart.


 

Arteries

When blood flows out of the heart, it enters the arteries. The blood is at very high pressure because it has been forced out of the heart as the ventricles have contracted (squeezed).  Arteries have very strong walls to be able to cope with the high pressure of the blood flowing through them.  The blood moves through the arteries with every heartbeat.  The thick muscular walls stretch and then bounce back into place because of the elastic fibres in the walls of arteries. 

The lumen is the hollow corridor that blood flows through. Arteries have a small lumen keeping the blood under high pressure.

 

Capillaries 

Arteries divide into smaller blood vessels.  The smallest blood vessels are called capillaries. The function of a capillary is to take nutrients and oxygen to cells and take waste products away. The structure of a capillary helps them do this. Capillaries have very thin walls -  they are only one cell thick. This means that the substances can diffuse in and out very quickly.


 

Veins

 

Image of vein with valves

 

Capillaries eventually join up again and form veins.  By the time the blood gets to the veins, it is at a much lower pressure than it was in the arteries.  Veins don't have thick, strong elastic walls. Veins have valves to stop the blood from flowing backwards. Arteries do not have valves because the force of the heartbeat keeps the blood moving. Veins have larger lumens than arteries because they are under less pressure and this helps the blood to flow more easily.

 

 

Gas Exchange

The lungs are adapted for gas exchange. Breathing involves exchanging gases in the lungs. 

 

Image of the human lungs

 

When you breathe in, oxygen in the inhaled air travels down your trachea, which branches off into bronchi (one branch is called the bronchus). This further divides into bronchioles and eventually, the oxygen diffuses through the tiny alveoli (air sacs) in your lungs into your bloodstream. The oxygen is transported to the heart via the pulmonary vein and then pumped around your body via the aorta from the heart. Carbon dioxide is the waste gas produced by respiration. Carbon dioxide diffuses from cells into the bloodstream and is pumped to the lungs via the pulmonary artery to be exhaled. 

 

Image of alveolus and gas exchange

 

 

The alveoli have a few adaptations that make gas exchange very efficient. They are only one cell thick, making them very thin, which allows gases to pass through easily and quickly. They also have a large surface area, allowing large amounts of gases to be exchanged with each breath.

 

In the following activity, you will compare the features of the circulatory system.

Capillaries have some special features that help them to do their job.

 

Discuss the adaptations of capillaries. 

 

The vena cava is the largest vein in the body. It carries deoxygenated blood back to the heart.

 

How are veins like the vena cava suited to their function? 

 

Image of vein with valves

Veins contain valves which prevent the back flow of blood

Veins have thick muscular walls

Veins are only one cell thick

The largest artery in the body is the aorta.

 

Describe and explain the features of the aorta.

 

Image of the aorta labelled on heart

Veins contain valves which prevent the back flow of blood

Veins have thick muscular walls

Veins are only one cell thick

 

Compare the different structures that help the lungs to function.

 

 
 
.Image of the human lungs

Column A

Column B

Trachea
Directs gases into and out of lungs
Bronchus and Bronchioles
Allow gas to move quickly throughout the lungs
Alveoli
Allow gases to be exchanged very quickly with the ...

Alveoli have several adaptations. 

 

Explain how these adaptations help to make gas exchange very efficient. 

 

Image of gas exchange in alveolus

 

Column A

Column B

Trachea
Directs gases into and out of lungs
Bronchus and Bronchioles
Allow gas to move quickly throughout the lungs
Alveoli
Allow gases to be exchanged very quickly with the ...

How are capillaries and alveoli similar? 

They are both one cell thick

They are both part of the blood

They both help to transport glucose

The body contains three different types of blood vessels - veins, arteries and capillaries.

 

Select the correct features for each of these blood vessels in the table below.

 VeinCapillaryArtery
Contains valves
Contains elastic fibres in blood vessel walls
Large lumen
Small lumen
Walls are one cell thick
Gas exchange occurs here

Compare the heart's chambers -  the right atrium and left ventricle.

The left ventricle has thicker walls than the right atrium because it has to place the blood under higher pressure

Blood enters the atrium before it enters a ventricle

Blood enters the ventricles before it enters the atrium

The right atrium has thicker walls than the ventricles

How does the concentration of oxygen in the blood in the aorta compare to the oxygen concentration found in the pulmonary artery?

Oxygen concentration is low in the aorta

Oxygen concentration is high in the aorta

Oxygen concentration is low in the pulmonary artery

Oxygen concentration is high in the pulmonary artery

What is the difference between the systemic and pulmonary circuit?

Oxygen concentration is low in the aorta

Oxygen concentration is high in the aorta

Oxygen concentration is low in the pulmonary artery

Oxygen concentration is high in the pulmonary artery

  • Question 1

Capillaries have some special features that help them to do their job.

 

Discuss the adaptations of capillaries. 

CORRECT ANSWER
EDDIE SAYS
Being thin allows capillaries to exchange gases and nutrients really quickly, making them super efficient at their job! Did you remember to use the word diffuse to describe the movement of particles between the blood and the cells of the body?
  • Question 2

 

The vena cava is the largest vein in the body. It carries deoxygenated blood back to the heart.

 

How are veins like the vena cava suited to their function? 

 

Image of vein with valves

CORRECT ANSWER
Veins contain valves which prevent the back flow of blood
EDDIE SAYS
It is important to remember that veins carry blood into the heart - the word vein contains the word in! This means that the blood in veins is not under high pressure and so need a bit of help to get it to flow back to the heart. This is why veins have valves - to stop blood flowing backwards. Try to remember: Veins contain Valves!
  • Question 3

The largest artery in the body is the aorta.

 

Describe and explain the features of the aorta.

 

Image of the aorta labelled on heart

CORRECT ANSWER
EDDIE SAYS
Remember: Arteries carry blood Away from the heart. The Aorta is one of the main Arteries. They all begin with the letter A!
  • Question 4
 

Compare the different structures that help the lungs to function.

 

 
 
.Image of the human lungs
CORRECT ANSWER

Column A

Column B

Trachea
Directs gases into and out of lun...
Bronchus and Bronchioles
Allow gas to move quickly through...
Alveoli
Allow gases to be exchanged very ...
EDDIE SAYS
The lungs have different structures that help them to do their job, which is gas exchange. Make sure you know the details of this process. Inhaled air travels into the lungs through the trachea and into the bronchus and then the bronchioles. From there, it passes into the alveoli, where oxygen diffuses into the bloodstream to be transported throughout the body. Carbon dioxide is returned to the lungs in the blood and diffuses into the lungs, via the alveoli, to be breathed out of the body.
  • Question 5

Alveoli have several adaptations. 

 

Explain how these adaptations help to make gas exchange very efficient. 

 

Image of gas exchange in alveolus

 

CORRECT ANSWER
EDDIE SAYS
Did you match them all up correctly? Alveoli are brilliantly adapted for their purpose. They have very thin walls, which allow gases to pass through quickly and this is helped by the fact that they are moist. They are also covered in capillaries, so that gases can diffuse between the lungs directly into the blood stream quickly and easily. Without these adaptations, gas exchange would be much slower and the body wouldn't be able to keep up its demands for respiration.
  • Question 6

How are capillaries and alveoli similar? 

CORRECT ANSWER
They are both one cell thick
EDDIE SAYS
Both alveoli and capillaries are extremely thin, allowing gases to pass through them very quickly by diffusion.
  • Question 7

The body contains three different types of blood vessels - veins, arteries and capillaries.

 

Select the correct features for each of these blood vessels in the table below.

CORRECT ANSWER
 VeinCapillaryArtery
Contains valves
Contains elastic fibres in blood vessel walls
Large lumen
Small lumen
Walls are one cell thick
Gas exchange occurs here
EDDIE SAYS
It is really important to know the difference between these three types of blood vessel. Veins carry blood into the heart, so the blood is not under much pressure. This means that they need valves and a large lumen to make it easier for the blood to flow. Veins have Valves to prevent backflow Capillaries are very thin (one cell thick), allowing quick gas exchange. Finally, arteries have a small lumen and strong muscular walls, which are needed to allow for the high pressure of the blood travelling through them.
  • Question 8

Compare the heart's chambers -  the right atrium and left ventricle.

CORRECT ANSWER
The left ventricle has thicker walls than the right atrium because it has to place the blood under higher pressure
Blood enters the atrium before it enters a ventricle
EDDIE SAYS
The atria (the plural of atrium) and ventricles are part of the heart, but have different purposes. Blood will enter the atrium first before it moves into the ventricles. The walls of the ventricles need to be stronger and thicker than those of the atria because blood leaves the ventricles under high pressure to carry it throughout the body.
  • Question 9

How does the concentration of oxygen in the blood in the aorta compare to the oxygen concentration found in the pulmonary artery?

CORRECT ANSWER
Oxygen concentration is high in the aorta
Oxygen concentration is low in the pulmonary artery
EDDIE SAYS
The aorta transports oxygenated blood from the heart to the rest of the body to be used for respiration, whereas the pulmonary artery transports deoxygenated blood to the lungs to collect more oxygen. This is the only artery that doesn't carry oxygenated blood. Well done - you've completed another activity. How are you feeling about this topic now?
  • Question 10

What is the difference between the systemic and pulmonary circuit?

CORRECT ANSWER
EDDIE SAYS
Did you get them all right? Did you spell systemic correctly? It's just system with -ic added to the end. These two circuits work together to ensure our cells have enough oxygen for respiration, as well as getting rid of waste materials.
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