1. The respiratory system
Respiration
The respiratory system

2. Respiration
Organisms must exchange oxygen and carbon dioxide with the environment.
Will look at plants and photosynthesis in ecosystems, and we have looked at cellular respiration
We are now moving to the more macro level of systems including circulation (as most systems do not work in isolation).
Will also look at blood in detail and at the circulation system, of plants as they too are organisms.

3. Exchanging gases with the environment
READ 8.1 on pg 130
Diffusion – you should only need to read and refresh here
Look at the extension exercise – note reason why people in higher altitude areas need more haemoglobin and red blood cells.
Extension exercise – need more haemoglobin and red blood cells due to the lower levels of atmospheric oxygen

4. What do we already know??
Draw me a picture of a torso showing the lungs
~ label your diagram as much as you can
~ can you describe what happens in inspiration and expiration

5. Bronchi receives oxygen rich blood from the pulmonary aorta.
Trachea (windpipe):
~2.5cm diameter
~11-12 cm long
~divides L & R Bronchi
~kept open by soft C shaped rings of cartilage
Bronchi receives oxygen rich blood from the pulmonary aorta.
Alveoli receives oxygen poor blood from the Pulmonary artery.
Trachea lined by cartilage so they can expand when food goes down the gullet next to it and puts pressure on it.
Bronchi (plural), Bronchus (single)
Alveoli receives oxygen via gas exchange through thin membranes of the alveoli /capillary walls.

6. Lungs
Surrounded by two thin sheets of tissue called the pleural membranes
~inner one covers the lungs
~outer one lines the thoracic cavity
There is a narrow space between the membranes called the pleural cavity – it contains fluid
This fluid is a surfactant – a compound that lowers the surface tension of a liquid.
The fluid acts as a lubricant so that the two membranes can slide over one another smoothly as we breathe in and out.

7. The overall respiration process
As we breathe in air through either the mouth or the nasal passages the diaphragm moves downwards and flattens out, which increases the size of the thoracic cavity.
The intercostal muscles
contract causing the ribs to
swing out further
expanding the thoracic
cavity sideways

8. Continued…
The increase in space means that the pressure becomes negative inside and allows us to draw air into the lungs.
Inhalation is an active process and requires energy.
Exhalation is passive and is a result of the recoiling of the thorax.

9. Tidal volume: The volume of air moved in and out with each breath
Tidal volume: The volume of air moved in and out with each breath. It varies depending upon demand or need for oxygen ie. Exercising vs resting
Vital capacity: This is the total amount of air that we can move in and out of our lungs.
Facts:
~ we breathe in about half a litre at rest.
~ Males usually breathe between 4-5 litres and females a little lower.
~ Airways are affected by things such as smoking, by affecting the surfactant (fluid) in the lungs that keeps the alveoli from collapsing
~ If the airways are affected, can result in thickening or reducing number of alveoli making lungs less efficient in gas exchange.

10. Breathing
Is actually controlled by the brain which registers the amount of carbon dioxide in the blood.
If it is too high we could die, therefore the brain tells the body to increase the respiration rate to help rid the cells of the carbon dioxide.
You will need to make a table and note all parts of the respiration system including the function
Larynx, Trachea, nasal passages (sinuses/nasal cavity/turbinates), bronchi, bronchioles, alveoli, capillaries, diaphragm, intercostals
Structure
location
function
pharynx
Back of throat
Channels air to lungs and food to stomach
Larynx