1. Respiratory System Students learn about: STUDENTS LEARN TO:
Structure and function
Analyse the various aspects of lung function through participation in a range of physical activities
Lung function (insiration, expiration)
Exchange of gases

2. The Respiratory System - Overview
The respiratory system refers to the set of organs that allows a person to breath.
This includes the:
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli.
These organs combine to allow for the exchange of oxygen and carbon-dioxide between the air in your lungs and your blood.
You will learn the structure and function of the respiratory system along with how gas is exchanged both externally and internally.
You will also participate in various practical activities where you monitor the response of this system to physical activity and learn to explain why these changes occur in relation to contributing to movement efficiency.
The respiratory system is obviously connected with the circulatory system and should be considered together.
Together they are called the cardiorespiratory or cardiovascular system.

3. Structure and Function
The structure of the respiratory system greatly enhances its ability to achieve its function.
The function of the system is to enable the transfer of oxygen into the blood and the removal of carbon-dioxide out of the blood.

4. Structure of the Respiratory System
The respiratory system consists of the following organs:
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli.
These organs combine to allow gas exchange
to occur between the lungs and the
circulatory system.

5. Structure of the Respiratory System cont…
Nasal cavity
Air travels through and is warmed
The small hairs in the cavity remove any small particles, such as dust or bugs.
Pharynx
Is where the nasal cavity and the oral cavity combine
Allows for the movement of air, food and liquid (the epiglottis is used to close off the air way when swallowing).
Larynx
Also known as the voice box, is used to make sound and to talk.
Trachea
Main air pipe that brings air down to the lungs.
The trachea then spits into two (2) main bronchi or bronchus, which continue to branch down to bronchioles.
These bronchioles bring the air to the alveoli which have a very large porous surface (has pores or holes in it for the exchange of gas), which are lined with fluid.
Each alveoli is surrounded by a mesh of capillaries to allow for gas exchange into the circulatory system.

6. Function of the Respiratory System
Allows us to breath and promote gas exchange with the circulatory system.
Achieved by having a large surface area caused by the alveoli.
This allows for a large area where gas can be exchanged. During gas exchange oxygen is transferred to the circulatory system, while carbon-dioxide is removed.
When exercise increases – the depth of breath increases. The number of aveoli being used for gaseous exchange increases – meaning the amount of oxygen transferred to the blood and carbon dioxide being removed increases.
The respiratory system will also increase the breathing rate allowing for a faster change of gas inside the lungs, which increases the amount of gas exchange per minute allowing for higher delivery of oxygen to the working muscle.
This improves movement efficiency of the muscles.

7. Lung Function - Inspiration
Lung function is to enable respiration
In order to achieve this your lungs must use inspiration and expiration.
Inspiration (inhale)
Many muscles are contracted:
Diaphragm
Intercostals
Pectorals
Causes a decrease in air pressure within the lungs.
This forces air from the atmosphere to move into the lungs to balance the pressure.
As the air comes into the body it is warmed by the blood vessels close to the surface in the respiratory system and moistened by the mucus lining the walls. This helps to increase gas exchange and makes breathing more comfortable.

8. Lung Function - Expiration
Expiration (exhale)
The body increases the pressure in the lungs in order to push air out of the lungs
Complete emptying of the lungs does not happen as this would cause a suction to occur, which would make it difficult to inspire again.
The trachea, bronchi and bronchioles are kept open by cartilage - ensures the airway stays open
Expiration is achieved through the elastic properties of the lungs and thoracic cage, as well as contraction of the intercostal muscles.
This increases the air pressure in the lungs pushing the air out into the atmosphere.
During exercise or physical activity, the lung function is to increase the respiratory rate in order to increase the volume of air moving in and out of the lungs per minute.
The volume of air inspired and expired also increases in response to physical activity in order to increase the oxygen absorbed through the alveoli and carbon-dioxide expelled from the body.

9. Exchange of Gases - External
EXTERNAL RESPIRATION
De-oxygenated (no oxygen) blood travels in the capillaries to the alveoli, where carbon- dioxide diffuses out of the blood and into the alveoli.
At the same time, oxygen that has been brought into the alveoli through inspiration diffuses across the alveoli membrane and into the capillaries. This is external respiration
This results in oxygenated blood being taken away from the lungs, back to the heart where it gets pumped around the body for use, while the carbon-dioxide is expired into the atmosphere.

10. Exchange of Gases - Internal
INTERNAL RESPIRATION
The internal exchange of gases occur between the capillaries that encase cells, for us particularly muscle cells, and the cell itself.
The oxygenated blood is brought to the muscle, where oxygen is taken out of the blood and transferred to the muscle tissue, while at the same time carbon-dioxide is taken out of the muscle cell and brought into the blood.
Oxygen is transported through the blood attached to haemoglobin, and travels in the muscle attached to myoglobin. 
The exchange of gases across the membranes of the capillary and the muscle is referred to as diffusion and is known as internal respiration
The carbon-dioxide is then taken to the lungs via the heart in order to remove the carbon- dioxide and receive oxygen again (external respiration).

11. Gaseous Exchange - Diagram