© boardworks ltd 20061 of 28 learning objectives © boardworks ltd 2006 1 of 28 learning objectives...

© Boardworks Ltd 20061 of 28

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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

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.


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.


The role of the blood

As well as controlling body temperature, one of the basic roles of the blood is as a transporter and it is through this function that the oxygen, glucose and waste products are all transported around the body.

Key TermsGlycogen: the main form of carbohydrate storage, which is converted into glucose as needed by the body to satisfy its energy needsLactic Acid: a mild poison and waste product of anaerobic respirationGaseous Exchange: the process where oxygen is taken in from the air and exchanged for carbon dioxide.


Make sure you understand the process of gaseous exchange and that aerobic respiration is with oxygen. Knowing activities that require aerobic respiration is also vital

It is crucial that you are able to identify the difference between aerobic and anaerobic exercise and respiration. You should be able to give good examples of activities for both

© boardworks ltd 20061 of 28 learning objectives © boardworks ltd 2006 1 of 28 learning objectives...

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