1. Preliminary PDHPE Core 2: The Body in Motion The Respiratory System

2. - Structure and function
Respiratory System
- Structure and function
In order to function, all body cells require oxygen which is delivered via the blood. It is the role of the respiratory system to supply oxygen to the blood and to remove carbon dioxide and waste products from the blood.
KEY TERMS:
Nose Lungs Larynx
Mouth Bronchus Alveoli
Pharynx Bronchiole Trachea

3. Structure
Function
Nose
The nose has a sticky surface and is covered with tiny hairs called cilia which trap dust particles. These will be moved towards the nose entrance to be sneezed out.
Mouth
Air moves into the mouth and the nose where it is warmed, filtered and humidified.
Pharynx
The pharynx is the throat. It carries food as well as air. Food continues down to the oesophagus. Air continues down to the trachea. The epiglottis is a flap which stops any food going down the trachea.
Larynx
The larynx is the voice box. It plays a large role in the production of human speech. As the air expelled from the lungs moves past, the vocal cords vibrate which produces sound.
Trachea
The trachea is also called the windpipe. It is the major airway to the lungs and is strengthened by cartilage rings. It moves down into the chest where it divides into the two bronchi.

4. Structure
Function
Lungs
There are two lungs which are cone-shaped and made of elastic tissue. They are protected by the sternum, ribs and spine. Along with the circulatory system, they play a role in gas exchange and the transport system
Bronchus
Two bronchus extend from the trachea. One bronchus goes to each lung.
Bronchiole
Once in the lungs, the bronchus divide into smaller branches called bronchioles
Alveoli
Bronchioles continue to divide until they end in tiny sacs called alveoli. They are elastic, thin-walled structures which are covered densely in capillaries containing blood. They play a major role in gaseous exchange.

5. Carbon Dioxide (CO2 Breathed out)
Respiration:
Respiration is the process by which the body takes in oxygen and removes carbon dioxide. Respiration uses oxygen as a vital ingredient to free energy from food and can be characterised by the following equation:
Glucose (from food)
Oxygen (O2 breathed in)
Carbon Dioxide (CO2 Breathed out)
Energy
Water

6. When humans breathe in (inhale), oxygen enters the respiratory system through the mouth and the nose. The inhaled breath then passes through the larynx (where speech sounds are produced) and the trachea, which is the main tube entering the chest cavity.
In the chest cavity , the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes further divide into many smaller tubes (bronchioles) , which connect to tiny air sacs called alveoli.
There are over 600 million of these sponge like alveoli in a healthy human lung. Oxygen inhaled into the lung passes through the thin wall of the alveoli and into the blood stream. At the same time, poisonous carbon dioxide passes back into the lung through the wall of the alveoli.

7. Inspiration: Expiration:
Respiratory System
- Lung Function (inspiration, expiration)
Inspiration:
Inspiration is breathing in. The diaphragm contracts, the ribs move up and out a little which enlarges the chest cavity. Because the chest is bigger, the pressure within the lungs decreases. The air moves from an area of high pressure to low pressure so the air is drawn into the lungs.
Expiration is breathing out. The diaphragm and ribs return to their at-rest state which decreases the size of the chest cavity. Thus the pressure inside the lungs is now high, so air is forced out of the lungs.
Expiration:

8. ‘Control of the breathing action is done by the muscular diaphragm, which lies across the bottom of the chest cavity. The diaphragm’s job is to help pump the carbon dioxide out of the lungs and create a space to allow oxygen to flow into the lungs. The ability to make use of atmospheric oxygen and remove poisonous carbon dioxide from the body is one that not only keeps human beings alive, but it can have a significant impact on the body’s ability to move efficiently.’
Question: What impact does respiratory efficiency have upon athletic performance?

9. Respiratory System
- Exchange of gases (internal, external)
‘Gas exchange occurs between the alveoli of the lungs and the blood in the capillaries. As mentioned before, a substance moves from an area of high concentration to an area of low concentration.
The alveoli in the lungs have a high level of oxygen whilst the blood in the capillaries have a low level of oxygen. Thus the oxygen in the alveoli moves across into the blood in the capillaries. It is then delivered back to the heart to undergo systemic circulation.
The blood in the capillaries has a high level of carbon dioxide whilst there is a low level of carbon dioxide in the alveoli. Thus the carbon dioxide in the blood moves across into the alveoli. It is then moved back through the respiratory system to be exhaled.’

10. Lung function
Respiration is the exchange of gases between the cells, blood and atmosphere. It involves four processes:
• pulmonary ventilation (breathing)—movement of air from the atmosphere into the alveoli
• pulmonary diffusion—exchange of oxygen and carbon dioxide between the lungs and the blood
• transport of respiratory gases—transportation of oxygen and carbon dioxide between the lungs and the tissue cells of the body via the blood
• internal respiration—exchange of gases between the blood capillaries and the tissue cells.

11. practical application
Heart rate test
As a class, participate in approximately 15 minutes of continuous aerobic exercise, such as bicycle riding, jogging or swimming.
Tasks
1 Describe the changes in heart rate and respiratory rate that you observed from the start of the activity until you reached a comfortable pace.
2 Compare how you felt just after starting the activity with how you felt after 10 minutes.
3 Explain what happened to your heart rate and respiration rate when you sprinted or went up a hill.
4 Explain how you felt immediately after ceasing activity.
5 Calculate how long it took for your heart rate and respiration rate to return to normal.