6.4 - Gas Exchange Flashcards
What is ventilation?
The pumping of gas into the lungs and removal of stale air
Why does ventilation occur?
To maintain the concentration gradient
Where does ventilation occur?
In the cytoplasm and mitochondria of cells
What does ventilation involve?
An increase in O2 intake and decrease in CO2 in the lungs helps maintain a high concentration of gases between alveoli and capillaries
This allows for faster diffusion
Lungs (3)
- air enters the trachea which branches into bronchi
- both the trachea and bronchioles are protected by rings of cartilage
- they then divide into bronchioles and then alveoli
What are alveoli?
The site of gas exchange
Type I pneumocytes (2)
- extremely thin cells with thin cell walls
- adapted for gas exchange and have a short diffusion pathway
Type II pneumocytes (2)
- secrete a solution containing a surfactant that creates a moist surface to prevent the alveoli sticking by adhesion to itself
- surfactant reduces surface tension
Ribcage movement in inspiration
Upwards and outwards
Diaphragm movement in inspiration
Contracts
Floor of thorax movement in inspiration
Downwards
Chest cavity volume in inspiration
Increases
Internal intercostal muscles inspiration
Relax
External intercostal muscles inspiration
Contract
Pressure in lungs in inspiration
Decreases
Air movement inspiration
In, because atmospheric air pressure is higher than lung air pressure
Ribcage movement in expiration
Downwards and inwards
Diaphragm movement in expiration
Relaxes
Floor of thorax movement in expiration
Upwards
Chest cavity volume in expiration
Decreases
Internal intercostal muscles in expiration
Contract
External intercostal muscles in expiration
Relax
Pressure in lungs in expiration
Increase
Air movement in expiration
Out
