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.
What can internal intercostal muscles do during exercise/coughing/sneezing?
They can contract to help push air out forcefully.
What is a spirometer?
A spirometer is a device used to measure lung volume.
How does it work?
A person using a spirometer breathes in and out of the airtight chamber, causing it to move up and down, leaving a trace on a graph which can then be interpreted.
What is total lung capacity?
How is total lung capacity calculated?
total volume of air in lungs.
vital capacity + residual volume
What is vital capacity?
Maximum volume of air that can be exchanged by breathing
What is tidal volume?
Volume of air breathed in or out in one breath
What is inspiratory reserve volume?
(IRV)
Extra air breathed in over and above the tidal volume
What is expiratory reserve volume?
(ERV)
Extra air breathed out over and above the tidal volume
What is residual volume?
The volume of air that remains in the lungs even after forced expiration
What is breathing rate?
(BR)
Number of breaths taken/min
What is ventilation rate?
(VR)
The total volume of air breathed in or out in 1 min
How to calculate VR?
Breathing rate x Tidal volume (TV)
How to calculate breathing rate?
VR/TV
