3.1.1 Exchange surfaces – Ventilation and gas exchange Flashcards
(13 cards)
In which structure of the mammalian breathing system does gas exchange take place at?
The alveolus/alveoli
How is a short diffusion distance produced at the alveoli?
- The alveoli are only one cell thick
- The alveoli are made up of thin, flat squamous epithelial cells
How is a steep diffusion gradient produced at the surface of the alveoli?
- Ventilation maintains a high concentration of oxygen and low concentration of carbon dioxide at the alveoli.
- A good blood supply maintains a high concentration of carbon dioxide and low concentration of oxygen in the blood capillary
Which substance prevents the alveoli from drying out?
Surfactant (a watery fluid).
Why does having millions of alveoli increase the exchange of gases?
It increases the surface area of the exchange surface.
Which 2 sets of muscles are involved in ventilation?
Diaphragm and intercostal muscles (external and internal).
What is ventilation?
Ventilation is the inhalation (breathing in) and exhalation (breathing out) of air.
During inhalation what happens to the external intercostal muscles and the diaphragm?
They contract.
During inhalation what happens to the rib cage and shape of the diaphragm?
- The rib cage moves up and out.
- The diaphragm flattens and moves down.
During inhalation what happens to the volume and pressure of the thoracic cavity?
It increases in volume and decreases in pressure.
During exhalation what happens to the external intercostal muscles and the diaphragm?
They relax.
During exhalation what happens to the rib cage and diaphragm?
- The rib cage moves in and down.
- The diaphragm becomes dome shaped.
During exhalation what happens to the volume and pressure of the thoracic cavity?
It decreases in volume and increases in pressure.
