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Compare Features of the Circulatory System

In this worksheet, students will 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.

The systems in the body all work together. The gaseous exchange system, the digestive system and excretory system all interact with the circulatory system in order to keep us alive. For example, during digestion, food is broken down by the stomach and small intestine. Water and dissolved food molecules are absorbed into the blood in capillaries. The glucose from the food is used for respiration, as well as oxygen from the gaseous exchange system.

Another example is the kidney. The blood passes through the kidneys where it is filtered at high pressure. The kidney selectively reabsorbs useful materials such as glucose, salt ions and water. Waste products such as urea are expelled from the body via the excretory system. 

 

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 the pulmonary circuit. The pulmonary circuit is where blood is transported between the lungs and 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, which 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 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 by the contraction (or squeezing) of the ventricles. 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 - 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 it to 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, so veins don't need to have thick, strong, elastic walls. Instead, 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.

The bicuspid and tricuspid valves are really important - they make sure that blood travels the correct way. The blood flowing into the ventricles is prevented from flowing back into the atrium. Tricuspid valves are found between the right atrium and ventricle, whereas the bicuspid valve is found between the left atrium and ventricle. ​

The semilunar valves are found between the aorta and left ventricle, and between the pulmonary artery and the right ventricle. The valves stop blood from flowing back into the ventricles. So you can see that without these valves, blood wouldn't be able to travel the right way!


Gas Exchange

The lungs are well 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 through 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 through the pulmonary artery, to be exhaled.

This goes to show how the circulatory system and gaseous exchange system work together!

 

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, allowing 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.

What is the difference between the systemic and pulmonary circuit? 

 

Column A

Column B

The systemic circuit
Is the route that takes blood from the heart to th...
The pulmonary circuit
Is the route that takes blood from the heart to th...

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

 

Describe the adaptations of capillaries. 

Column A

Column B

The systemic circuit
Is the route that takes blood from the heart to th...
The pulmonary circuit
Is the route that takes blood from the heart to th...

Locate the tricuspid and bicuspid valves. 

 

Add pic 364774574

 

 

 

 

 

 

 

A

B

C

D

The respiratory system and the circulatory system interact with one another.

The alveoli allow gas exchange to occur - they have several adaptations. 

 

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

 

Image of gas exchange in alveolus

A

B

C

D

Capillaries form part of the circulatory system and alveoli form part of the gas exchange system. 

 

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

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

Explain the role of semilunar valves. 

They allow blood in the heart to move in any direction

They allow blood to flow into the ventricles

They stop blood from flowing back into the ventricles

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

Oxygen concentration is lower in the aorta

Oxygen concentration is higher in the aorta

Oxygen concentration is lower in the pulmonary artery

Oxygen concentration is higher in the pulmonary artery

The bicuspid and tricuspid valves are found in the heart.

 

What is the difference between the bicuspid and tricuspid valves?

The tricuspid valve is found between the left atrium and ventricle

The tricuspid valve is found between the right atrium and ventricle

The bicuspid valve is found between the right atrium and ventricle

The bicuspid valve is found between the left atrium and ventricle

How does the human circulatory system interact with the digestive, gaseous exchange and excretory systems? 

Column A

Column B

Digestive system
The blood carries oxygen to cells for respiration ...
Gaseous exchange system
The blood travels through the kidneys with urea be...
Excretory system
The blood carries nutrients around the body
  • Question 1

What is the difference between the systemic and pulmonary circuit? 

 

CORRECT ANSWER

Column A

Column B

The systemic circuit
Is the route that takes blood fro...
The pulmonary circuit
Is the route that takes blood fro...
EDDIE SAYS
Remember that our blood flows in a double circulatory system! This means that the blood flows through the heart twice in a complete cycle. It also means that oxygenated and deoxygenated blood don't mix. The pulmonary circuit deals with any blood that goes between the heart and the lungs, and the systemic circuit is for any other blood. These two circuits work together to ensure our cells have enough oxygen for respiration, as well as getting rid of waste materials.
  • Question 2

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

 

Describe the adaptations of capillaries. 

CORRECT ANSWER
EDDIE SAYS
The body really is an amazing organism! Every part of it is carefully adapted to fulfill its function. Being thin allows capillaries to exchange gases and nutrients really quickly, making them super efficient at their job!
  • Question 3

Locate the tricuspid and bicuspid valves. 

 

Add pic 364774574

 

 

 

 

 

 

 

CORRECT ANSWER
B
C
EDDIE SAYS
This was a hard question - how did you get on with it? The tricuspid valve can be found between the right atrium and ventricle, whereas the bicuspid valve is found between the left atrium and ventricle.
  • Question 4

The respiratory system and the circulatory system interact with one another.

The alveoli allow gas exchange to occur - they have several adaptations. 

 

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

 

Image of gas exchange in alveolus

CORRECT ANSWER
EDDIE SAYS
Well done if you succeeded in filling in all these blanks correctly! Did you remember that the alveoli are moist, which helps the gases to dissolve and therefore pass more easily through into the blood? Without these adaptations, gas exchange would be much slower and the body wouldn't be able to keep up with its demands for respiration.
  • Question 5

Capillaries form part of the circulatory system and alveoli form part of the gas exchange system. 

 

How are capillaries and alveoli similar? 

CORRECT ANSWER
They are both one cell thick
EDDIE SAYS
You may well have been a bit muddled by these two because of their similarities - so it's not a bad idea to spend some time comparing them! Both alveoli and capillaries are extremely thin, allowing gases to pass between them very quickly. This makes them both superbly adapted for their specific functions. They both help to transport oxygen and carbon dioxide, but not glucose - so option three was incorrect. Also, the alveoli are part of the respiratory system, not a part of the blood.
  • Question 6

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
This is a challenging question, so well done if you got it correct! The atriums and ventricles are both parts of the heart but have different purposes. Blood enters the atrium first before it moves into the ventricles.
  • Question 7

Explain the role of semilunar valves. 

CORRECT ANSWER
They stop blood from flowing back into the ventricles
EDDIE SAYS
Veins really need valves otherwise blood can flow backwards! Valves are really important in keeping blood moving in the right direction. Without these valves, many health issues could arise. The semilunar valves are found between the aorta and the left ventricle, as well as between the pulmonary artery and the right ventricle. Their function is to stop blood flowing back into the ventricles. Phew - what a challenging activity this was! You've completed it now and hopefully, you feel a bit more confident on this topic than before you started!
  • Question 8

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

CORRECT ANSWER
Oxygen concentration is higher in the aorta
Oxygen concentration is lower in the pulmonary artery
EDDIE SAYS
These go in pairs, so if you got one right, then it should be easy to find the other correct one! Both of these blood vessels are arteries, so they are transporting blood away from the heart. 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. The pulmonary artery is the only artery that carries deoxygenated blood.
  • Question 9

The bicuspid and tricuspid valves are found in the heart.

 

What is the difference between the bicuspid and tricuspid valves?

CORRECT ANSWER
The tricuspid valve is found between the right atrium and ventricle
The bicuspid valve is found between the left atrium and ventricle
EDDIE SAYS
Well done if you remembered which way round these went! These valves prevent a back flow of blood and ensure the blood flows in the correct direction.
  • Question 10

How does the human circulatory system interact with the digestive, gaseous exchange and excretory systems? 

CORRECT ANSWER

Column A

Column B

Digestive system
The blood carries nutrients aroun...
Gaseous exchange system
The blood carries oxygen to cells...
Excretory system
The blood travels through the kid...
EDDIE SAYS
These different systems interact with one another to allow the body to function. They all depend on the circulatory system to transport these essential substances throughout the body.
---- OR ----

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