3.1.1 Exchange Surfaces Flashcards
(3) Examples of nutrients
Mineral ions, vitamins, amino acids
(2) Examples of excretory products
CO2, nitrogenous compounds
What are secretory products?
Anything released from the cell that isn’t a waste product.
What are the features of a good gas exchange system?
1) Large surface area
2) Thin barrier
3)Good blood supply
How does a large surface area help?
How?
More space of molecules to pass through.
Usually done through folding and projections
How does a thin barrier help?
Reduce diffusion distance.
How does a good blood supply help?
Maintains a steep concentration gradient..
(2) What does ventilation do?
Ensures that:
* Concentration of O2 in the air of alveolus remains higher than that in the blood.
* Concentration of CO2 in alveoli remains lower than that in the blood.
What is perfusion?
The movement of blood across the internal side of the exchange surface.
What does perfusion do?
It constantly takes O2 away to the tissues and brings CO2 to be excreted.
Why do gas exchange surfaces need to be moist?
For O2 and CO2 to diffuse across them in solution.
Where are alveoli located?
In clusters at the ends of terminal bronchioles.
(2) What is the epithelia lining of the alveoli made of?
- Type 1 - Squamous alveolar epithelial cells.
- Type 2 - Septal cells = large epithelial cells responsible for production of surfactant.
(5) What is the process of inspiration?
- Diaphragm contracts to move down and become flatter - displaces the digestive organs downwards.
- External intercostal muscles contract to raise the ribs.
- Volume of chest cavity is increased.
- The pressure in the chest cavity drops below the atmospheric pressure.
- Air is moved into the lungs.
(5) What is the process of expiration?
- Diaphragm relaxes and is pushed up by displaced organs underneath.
- External intercostal muscles relax and the ribs fall.
- Volume of the chest cavity decreases.
- Pressure in lungs increases and rises above the pressure in the surrounding atmosphere.
- Air is moved out the lungs.
