Efficient Gas Exchange in the Lugns Flashcards
The Respiratory System (18 cards)
How does a large surface area allow for efficient gas exchange?
The alveoli give the lungs a huge internal surface area, so that large amounts of gases can be exchanged in a relatively short time.
How many alveoli are there?
Estimates of the number of alveoli in the lungs vary considerably, but there are hundreds of millions of them
What is the total surface area of alveoli?
they probably have a total surface area of 50–80 m2 – about one-third the area of a tennis court
How do thin walls allow for efficient gas exchange?
The membrane that forms the wall of the alveolus is very thin, so that gas molecules do not have far to travel when moving into or out of the blood.
How thick is the alveoli wall?
The wall has only one layer of cells and is only 1 micrometre (1 µm, or 1/1000 of a millimetre) thick.
Why is the positioning of the lungs important?
The lungs are positioned deep inside the body to prevent excessive evaporation of the fluid that covers the respiratory surfaces
How does a moist lining allow for efficient gas exchange?
It is important that the membrane of the alveolus be covered by a thin layer of moisture because gases can diffuse into and out of the blood only when they are dissolved in fluid.
How does blood supply allow for efficient gas exchange?
Each alveolus is well supplied with blood vessels, so that as much blood as possible is close to the air in the alveolus.
Why is the continuous flow of blow important?
The continuous flow of blood helps to maintain a difference in concentrations of oxygen and carbon dioxide between the blood and the air in the lungs.
How is lung volume changed?
By movements of the respiratory muscles, so that air is made to flow into and out of the lungs
How does constant air flow allow for efficient gas exchange?
Constant changing of the air in the alveoli helps to ensure that there is always a concentration gradient of oxygen and carbon dioxide between the air and the blood.
What is needed for diffusion of gases?
For diffusion of gases into and out of the blood, there must be a concentration gradient
What is a concentration gradient?
A difference in gas concentration between the air in the alveoli and the blood in the capillaries.
How is the concentration gradient for oxygen and carbon dioxide maintained?
- Constant flow of blood through capillaries
- Movement of air into/out of alveoli as we breathe in and out.
Describe the flow of blood through the capillaries
As the blood flowing through the capillaries around each alveolus picks up oxygen and loses carbon dioxide, it is replaced by more blood being pumped into the capillaries
How does constant flow of blood through the capillaries maintain the concentration gradient?
This ‘new’ blood is low in oxygen and high in carbon dioxide, so the concentration gradient is maintained
Describe the movement of air into/out of the alveoli as we breathe
The air that has picked up carbon dioxide from, and lost oxygen to, the blood is replaced by ‘new’ air with each breath.
How does the movement of air into and out of the alveoli as we breathe maintain the concentration gradient?
The ‘new’ air is low in carbon dioxide and high in oxygen.
