UNIT 1 – Area of Study 1

Body Systems & Human Movement

THE RESPIRATORY SYSTEM

THE RESPIRATORY SYSTEM

The function of the respiratory system is to :Breath in air from the environment.Transfer oxygen into the blood.Remove carbon-dioxide from the

blood.Return air back to the environment.Create speech ( as air is moved out over

the larynx )

THE RESPIRATORY SYSTEM The pathway of air from the environment to the

lungs is as follows

1. NOSE & MOUTH – air is breathed in through the nose & mouth.

2. PHARYNX – air passes through the throat.

3. LARYNX – air passes over the larynx ( or voicebox ).

4. Air travels down the TRACHEA (or windpipe)

5. Air branches into the LEFT BRONCHUS & RIGHT BRONCHUS.

6. The bronchi divide into smaller BRONCHIOLES.

7. At the and of the bronchioles are the ALVEOLI ( tiny air sacs ) where the transfer of gases takes place.

THE RESPIRATORY SYSTEM

TRACHEA

LEFTBRONCUS

BROCHIOLES

RIGHTBRONCUS

THE MECHANICS OF

BREATHING INSPIRATION :

DIAPHRAGM contracts & flattens to make the chest

cavity bigger.

The DIAPHRAGM muscle contracts & flattens, whilst the INTERCOSTAL muscles raise the thorax and sternum out.

The chest cavity is now bigger which lowers the pressure in the lungs to less than that of the environment.

Air is drawn into the lungs ( as gases will always move from higher pressure to lower pressure areas ).

THE MECHANICS OF

BREATHING EXPIRATION :

The DIAPHRAGM muscle relaxes and forms a dome shape, whilst the INTERCOSTAL muscles relax to lower thorax and sternum in. The chest cavity is now smaller which raises the pressure in the lungs to more than that of the environment.

Air is drawn out of the lungs ( as gases will always move from higher pressure to lower pressure areas ).

DIAPHRAGM relaxes to make the chest cavity smaller.

LUNG VOLUMES VITAL CAPACITY– the max amount

of air that can be breathed out after a max inspiration.

TIDAL VOLUME – the amount of air breathed in and out with each breath.

INSPIRATORY RESERVE VOLUME – the max amount of air that can be breathed in on top of a normal inspiration.

EXPIRATORY RESERVE VOLUME – the max amount of air that can be breathed out after a normal expiration.

RESIDUAL VOLUME – the amount left in the lings after a max forced expiration.

TOTAL LUNG CAPACITY – residual volume plus vital capacity.

LUNG VOLUMES VITAL CAPACITY– the max amount

of air that can be breathed out after a max inspiration.

TIDAL VOLUME – the amount of air breathed in and out with each breath.

INSPIRATORY RESERVE VOLUME – the max amount of air that can be breathed in on top of a normal inspiration.

EXPIRATORY RESERVE VOLUME – the max amount of air that can be breathed out after a normal expiration.

RESIDUAL VOLUME – the amount left in the lings after a max forced expiration.

TOTAL LUNG CAPACITY – residual volume plus vital capacity.

RESIDUAL VOLUME

GASEOUS EXCHANGE

Gaseous exchange occurs because of differences in concentration or pressure levels.

Gases will always move from an area of high concentration or pressure to an area of low concentration or pressure.

GASEOUS EXCHANGE

When air is breathed in and arrives at the alveoli it has a high concentration of oxygen.

The capillaries surrounding the alveoli have blood with a low concentration of oxygen.

Therefore oxygen will diffuse from the alveoli into the capillaries and combine with haemoglobin in the red blood cells.

ALVEOLI CAPILLARIES O2

O2

O2

O2

O2 O2

O2

O2

O2 O2

CAPILLARY

GASEOUS EXCHANGE

When oxygenated blood arrives at the muscle it has a high concentration of oxygen.

The working muscle has a low concentration of oxygen.

Therefore oxygen will diffuse from the capillaries into the muscle cells.

CAPILLARIES MUSCLE TISSUE O2

O2

O2

O2

O2 O2

O2

O2

O2 O2

CAPILLARY

GASEOUS EXCHANGE

The working muscles will produce a waste product called carbon-dioxide ( CO2 )

The working muscle builds up a high concentration of CO2.

The capillaries arriving at the muscle will have a low concentration of CO2.

Therefore CO2 will diffuse from the muscle into the capillaries.

( only about 20 % of CO2 is carried by the haemoglobin – the rest is dissolved in the plasma or in the form of a bicarbonate ion )

MUSCLE TISSUE CAPILLARIES CO2

CO2

CO2

CO2

CO2

CO2 CO2

CO2

CO2

CO2 CO2

CAPILLARY

GASEOUS EXCHANGE

The blood arriving back at the lungs has a high concentration of CO2.

The alveoli have a low concentration of CO2.

Therefore CO2 will diffuse from the capillaries into the alveoli so it can be breathed out.

CAPILLARIES ALVEOLI CO2

CO2

CO2

CO2

CO2

CO2 CO2

CO2

CO2

CO2 CO2

CAPILLARY

RESPONSES TO EXERCISE

The acute responses of the respiratory system to exercise are :

Increased respiratory rate from 15 at rest to 40-50 during exercise.

Increased tidal volume from 0.5 litres at rest to 2.5 litres during exercise.

Increased ventilation ( RR X TV ) from 6 or 7 litres at rest to about 125 litres during exercise.

Increased lung diffusion ( alveoli to blood )

Increased O2 uptake ( amount of O2 used by body per minute ) – VO2 max is the maximum amount of oxygen that can be consumed and is a measure of a person’s aerobic capacity.

REVISION QUESTIONS1. The function of the respiratory system is to :

A/ pump blood around the body.B/ regulate hydration levels.C/ extract oxygen from the air.D/ all of the above.E/ none of the above.

2. At rest, the average adult would breathe approximately:A/ 35 times per minute.B/ 25 times per minute.C/ 15 times per minute.D/ 5 times per minute.

3. The pathway from the environment to the lungs is as follows:A/ pharynx - larynx - trachea - bronchi - bronchioles - alveoli.B/ trachea - pharynx - bronchi - larynx - bronchioles - alveoli.C/ alveoli - bronchioles - bronchi - trachea - pharynx - larynx.D/ larynx - pharynx - trachea - bronchi - bronchioles - alveoli.

REVISION QUESTIONS4. Ventilation is:

A/ the amount of air breathed in one minute.B/ tidal volume multiplied by respiratory rate.C/ the amount of air per breath multiplied by the number of breaths per minute.D/ all of the above.E/ none of the above.

5. The major muscles used in respiration are the:A/ diaphragm and abdominals.B/ diaphragm and intercostals.C/ Abdominals and intercostals.D/ trapezius and peroneus longus.

6. During expiration the diaphragm:A/ contracts and flattens.B/ relaxes and flattens.C/ contracts and becomes dome shape.D/ relaxes and becomes dome shape.

REVISION QUESTIONS7. The volume of air remaining in the lungs after a forced max. expiration is the:

A/ expiratory reserve volume.B/ tidal volume.C/ residual volume.D/ vital capacity.

8. The exchange of gas in the lungs takes place between which two structures ?A/ capillaries and muscle cellsB/ capillaries and alveoliC/ arteries and veinsD/ veins and alveoli

9. The exchange of gas at the muscle takes place between which two structures ?A/ capillaries and muscle cellsB/ capillaries and alveoliC/ arteries and veinsD/ veins and muscle cells