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The Respiratory System

In this worksheet, students will learn about the respiratory system that allows cells in our body to utilise oxygen breathed in and perform respiration, a chemical reaction that releases the energy needed for our body to perform necessary functions.

'The Respiratory System' worksheet

Key stage:  KS 3

Curriculum topic:  Biology: Structure and Function of Living Organisms

Curriculum subtopic:  Gas Exchange Systems (Breathing)

Difficulty level:  

down

Worksheet Overview

QUESTION 1 of 10

The respiratory system is made of organs that enable us to use oxygen from the air we breathe and remove carbon dioxide, which is poisonous. The oxygen is used in a chemical reaction that takes place in all cells; respiration. For respiration, the respiratory system and the digestive system work together as the oxygen reacts with the glucose provided by food we eat. The products of respiration are water and carbon dioxide and we remove them from our body when we exhale. Take care not to confuse breathing in and out with respiration; breathing is only part of respiration.

The diagram shows the respiratory system in humans.

 

 

The nose and nasal cavity form the first port of entrance of air into our body. The mouth can be used as a secondary entrance when needed. The pharynx is the throat, which is made of muscles and extends from the end of the nasal cavity to the larynx. The larynx is the voice box and connects the pharynx to the trachea (windpipe). The epiglottis is a piece of cartilage that covers the larynx during swallowing to prevent food going down the trachea, which could make us choke. The trachea allows air to pass through to the lungs. It is covered by the epithelium, made of cells that produce mucus, which traps germs, dirt and dust to prevent it going to the lungs. Epithelial cells have hair-like structures on their surface called cilia. Cilia push dirt towards the pharynx. Towards its end the trachea splits into two branches, the left and the right bronchus. Each bronchus leads to a lung. The bronchi keep separating into branches, which in turn separate into smaller branches, the bronchioles that spread throughout the lungs. The lungs are spongy structures made of many capillaries and millions of tiny air sacs, each one called alveolus

 

Gas exchange

Getting oxygen from the air into the blood and removing carbon dioxide is referred to as gas exchange. The alveoli have several adaptations that allow gas exchange to take place with the maximum effect: 

1. They provide a large surface area where gas exchange can take place.

2. Their walls are moist and very thin (one cell thick).

3. They have a lot of tiny blood capillaries passing through them.

 

The diagram shows the structure of the alveoli.

 

 

Blood cells pass through the tiny capillaries around the alveoli. The concentration of oxygen in the blood at that point is much lower than in the alveoli, as we have just inhaled. The mechanism of diffusion allows substances to move from an area of a higher concentration to an area of a lower concentration, therefore oxygen passes through the walls of the alveoli into the blood stream, which takes it to every single cell in the body. At the same time, carbon dioxide brought to the lungs from the rest of the body diffuses into the alveoli so it can be exhaled.

 

Effects of exercise, asthma and smoking

When we exercise our cells need more energy, so more oxygen is taken in to allow a higher rate of respiration. Hard exercise can cause lack of oxygen in the cells. Then the body can go into anaerobic respiration, which produces lactic acid. Lactic acid is toxic, so our heart rate increases to ensure lactic acid is carried away to the liver to be broken down. 

Things like pollen, hair and dust can cause an asthma attack, which means the bronchioles release a chemical called histamine. Histamine causes inflammation of the cells in the airways, so excess mucus is produced and they swell. The airways narrow, which makes it difficult for air to pass through as we breathe. People who suffer from asthma have to use an inhaler, which relaxes the airways and makes breathing easier.

Smoking causes cilia of the epithelial cells to paralyze, which means they are not as effective in removing germs, dust and dirt trapped in the mucus. More mucus is produced and this leads to smoker's cough. A result of this can be chronic bronchitis. Mucus production further increases and the lining of the bronchioles thickens. Eventually, this can lead to emphysema and lung cancer.

What is the name of the chemical reaction that takes place in all cells in our body and uses oxygen and glucose to release energy?

Write one word.

Complete this sentence.

The pharynx extends from the nasal cavity to the _________.

trachea

larynx

bronchus

What is the piece of cartilage that covers the larynx during swallowing?

windpipe

trachea

epiglottis

The epithelial cells produce a substance that traps germs, dirt and dust in order to prevent them entering the lungs. What is the name of this substance?

Write one word.

Towards its end the trachea splits into two branches, the bronchi. What is the singular form of the word 'bronchi'?

bronchus

bronchiole

Complete this sentence.

The lungs are made of millions of tiny air sacs called ________.

bronchioles

alveolus

alveoli

Pick the correct alveoli adaptation for gas exchange.

The alveoli have very thick walls to prevent excess carbon dioxide entering the lungs.

The alveoli provide a restricted surface area for gas exchange to take place.

The alveoli have many blood capillaries around them.

What is the mechanism that allows gas exchange through the walls of the alveoli?

active transport

osmosis

diffusion

During an asthma attack, the bronchioles release a chemical that causes inflammation. What is this chemical?

histamine

carbon dioxide

lactic acid

What structures in the airways are paralyzed by smoking?

bronchioles

bronchi

cilia

  • Question 1

What is the name of the chemical reaction that takes place in all cells in our body and uses oxygen and glucose to release energy?

Write one word.

CORRECT ANSWER
respiration
EDDIE SAYS
The chemical reaction that takes place in all cells in our body and uses oxygen and glucose to release energy is called respiration.
  • Question 2

Complete this sentence.

The pharynx extends from the nasal cavity to the _________.

CORRECT ANSWER
larynx
EDDIE SAYS
The pharynx extends from the nasal cavity to the larynx.
  • Question 3

What is the piece of cartilage that covers the larynx during swallowing?

CORRECT ANSWER
epiglottis
EDDIE SAYS
The epiglottis is made of cartilage and covers the larynx during swallowing to prevent food entering the airways.
  • Question 4

The epithelial cells produce a substance that traps germs, dirt and dust in order to prevent them entering the lungs. What is the name of this substance?

Write one word.

CORRECT ANSWER
mucus
EDDIE SAYS
Epithelial cells produce mucus that traps germs, dirt and dust in order to prevent them entering the lungs.
  • Question 5

Towards its end the trachea splits into two branches, the bronchi. What is the singular form of the word 'bronchi'?

CORRECT ANSWER
bronchus
EDDIE SAYS
We say one bronchus and more than one bronchi. Bronchioles are further branches of the bronchi into the lungs.
  • Question 6

Complete this sentence.

The lungs are made of millions of tiny air sacs called ________.

CORRECT ANSWER
alveoli
EDDIE SAYS
The tiny air sacs in our lungs are called alveoli. Alveolus is just one of the many alveoli, so this option is not correct grammatically.
  • Question 7

Pick the correct alveoli adaptation for gas exchange.

CORRECT ANSWER
The alveoli have many blood capillaries around them.
EDDIE SAYS
The alveoli have several adaptations that allow gas exchange to take place with the maximum effect:
1. They provide a large surface area where gas exchange can take place.
2. Their walls are moist and very thin (one cell thick).
3. They have a lot of tiny blood capillaries passing through them.

The last option is correct.
  • Question 8

What is the mechanism that allows gas exchange through the walls of the alveoli?

CORRECT ANSWER
diffusion
EDDIE SAYS
Gas exchange in the alveoli takes place by diffusion.
  • Question 9

During an asthma attack, the bronchioles release a chemical that causes inflammation. What is this chemical?

CORRECT ANSWER
histamine
EDDIE SAYS
During an asthma attack, the bronchioles release histamine, a chemical that causes inflammation.
  • Question 10

What structures in the airways are paralyzed by smoking?

CORRECT ANSWER
cilia
EDDIE SAYS
Cilia in epithelial cells are paralyzed by smoking.
---- OR ----

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