© boardworks ltd 20061 of 28 the respiratory system © boardworks ltd 2006 1 of 28 these icons...

© Boardworks Ltd 20061 of 28

The Respiratory System


These icons indicate that teacher’s notes or useful web addresses are available in the Notes Page.

This icon indicates that the slide contains activities created in Flash. These activities are not editable.

For more detailed instructions, see the Getting Started presentation.

KS4 Physical Education


Lea

rnin

g o

bje

ctiv

es


Learning objectives

The structures of the respiratory system and their functions

The mechanisms of breathing

How gases are exchanged during breathing

The composition of inhaled and exhaled air

The different measurements of lung capacity and breathing

The effects of exercise on the respiratory system

What is meant by aerobic and anaerobic respiration

The oxygen debt.

What we will learn in this presentation:


The respiratory system


The nasal passages and lungs

Air is drawn into the body via the nose or mouth. There are advantages to breathing through your nose:

Air then travels through the larynx, trachea (windpipe), bronchi (one bronchus to each lung) and bronchioles to the alveoli, where oxygen passes into the bloodstream.

the air is warmed so that it is closer to body temperature

tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli

mucus moistens the air, making it easier for the alveoli to absorb.


When you breathe in:

intercostal muscles between the ribs contract, pulling the chest walls up and out

the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest

the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth.

Mechanisms of breathing – inspiration

Diaphragm contracts and moves down

Intercostal muscles pull ribs

up and out


Mechanisms of breathing – inspiration


Mechanisms of breathing – expiration

When you breathe out:

Intercostal muscles between the ribs relax so that the chest walls move in and down.

The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest.

The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth.

Diaphragm relaxes and bulges up

Ribs move in and down


Mechanisms of breathing – expiration


Gas exchange at the alveoli

The alveoli are bunches of tiny air sacks inside the lungs.

Each individual sack is called an alveolus.

When you breathe in, they fill with air.

The alveoli are covered in tiny capillaries (blood vessels).

Gases can pass through the thin walls of each alveolus and capillary, and into the blood stream.

Gases can also pass from the blood stream, into the alveolus.


Gas exchange at the alveoli


Composition of inhaled and exhaled air

GasAmount in inhaled air

Amount in exhaled air

Oxygen

Carbon dioxide

Nitrogen

Water vapour

17%

3%

79%

Large amount

21%

Very small amount

79%

Small amount

Why does mouth-to-mouth resuscitation work?

What are the main differences between inhaled and exhaled air?


Measuring breathing

Tidal volume is the amount you breathe in and out in one normal breath.

Residual volume is the amount of air left in your lungs after you have breathed out as hard as you can.

Minute volume is the volume of air you breathe in one minute.

Respiratory rate is how many breaths you take per minute.

Vital capacity is the maximum volume of air you can breathe out after breathing in as much as you can.


Measuring breathing


Calculating minute volume

Question

If you breathe 14 times in one minute (respiratory rate) and you breathe 0.5 litres in each breath, what is your minute volume?

Answer:Minute volume = 14 × 0.5 litres

= 7.0 litres

Remember:

You can calculate a person’s minute volume by multiplying the volume of air they breathe in one breath, by their respiratory (breathing) rate.

Minute volume is the volume of air you breathe in one minute.


Breathing during exercise

During exercise the muscle cells use up more oxygen and produce increased amounts of carbon dioxide.

Your lungs and heart have to work harder to supply the extra oxygen and remove the carbon dioxide.

Your breathing rate increases and you breathe more deeply.

Heart rate also increases in order to transport the oxygenated blood to the muscles.


Breathing during exercise

Muscle cell respiration increases – more oxygen is used up and levels of CO2 rise.

The brain detects increasing levels of CO2 – a signal is sent to the lungs to increase breathing.

Breathing rate and the volume of air in each breath increase. This means that more gaseous exchange takes place.

The brain also tells the heart to beat faster so that more blood is pumped

to the lungs for gaseous exchange.

More oxygenated blood gets to the muscles and more CO2 is removed.


Breathing changes during exercise

During rest During exercise

Respiratory rate 14 breaths/ minute 32 breaths/ minute

Volume per breath

0.4 litres 2.4 litres

Minute volume ? ?

Look at these statistics for a 16 year-old athlete:

Calculate the athlete’s minute volumes during rest and exercise.

Rest minute volume = 5.6 litresExercise minute volume = 76.8 litres


The effects of exercise on lung structures

The respiratory muscles (the diaphragm and intercostals) get stronger, so they can make the chest cavity larger.

This larger chest cavity means more air can be inspired, therefore increasing your vital capacity.

More capillaries form around the alveoli, so more gaseous exchange can take place.

In the long-term, regular exercise strengthens the respiratory system.

Gas exchange can now take place more quickly meaning exercise can be maintained

at a higher intensity for longer.


Respiration

Glucose from food is used to fuel exercise.

Respiration is the process that takes place in living cells which releases energy from food molecules.

Waste products, including carbon dioxide, are produced as a result of the chemical reactions. These must be removed and excreted.

glucoseoxygen

energy

respirationOxygen is required to ‘break down’ the glucose to produce energy. This energy is used to make muscles contract.


Aerobic respiration

Aerobic exercise can be maintained for long periods without the performer getting breathless or suffering muscle cramps. Moderate activities like walking, jogging, cycling and swimming use aerobic respiration.

There are two different types of respiration.

When you exercise at a steady, comfortable rate, the cardiovascular system is able to supply the muscles with all the oxygen they need.

Under these conditions, aerobic respiration takes place.

glucose + oxygen energycarbon dioxide

+ + water


Aerobic respiration


Anaerobic respiration

When you exercise at a high intensity, the cardiovascular system cannot supply enough oxygen to the muscles.

Under these conditions, anaerobic respiration takes place.

With no oxygen available, glucose is burned to produce energy and lactic acid.

Lactic acid is a mild poison. As it builds up, it causes muscle pain and eventually cramp.

Short, intense activities like sprinting, weightlifting, jumping and throwing use anaerobic respiration.

glucose energy + lactic acid


Oxygen debt

After anaerobic activity, oxygen is needed to neutralize the lactic acid. This is called an oxygen debt. It is repaid after exercise.

The oxygen reacts with the lactic acid to form CO2 and water.

Rapid and deep breathing is needed for a short period after high intensity exercise in order to repay the debt.

This also helps to remove the carbon dioxide which accumulates in the blood during intense exercise.


Anaerobic exercise


Exam-style questions

1. Describe the passage of oxygen from the nasal passages to the bloodstream.

2. David goes jogging once a week for 45 minutes.

David tries to increase his pace. He finds that he is forced to stop running and breathe hard for several minutes.

a) List two differences between the air that David inhales and the air that he exhales while jogging.

b) What two substances are used by David’s body cells to produce energy? What are the products of this reaction?

c) Explain why David had to stop.

d) How did breathing hard help him to recover?


Can you remember all these keywords?

Larynx

Trachea

Bronchus / Bronchi

Bronchioles

Alveoli

Diaphragm

Intercostal muscles

Oxygen uptake

Tidal volume

Respiratory rate

Minute volume

Vital capacity

Residual volume

Aerobic respiration

Anaerobic respiration

Oxygen debt

Lactic acid

© boardworks ltd 20061 of 28 the respiratory system © boardworks ltd 2006 1 of 28 these icons...

Documents