6.4 Gas Exchange Flashcards
What are alveoli?
All bronchioles end with alveoli, which are air sacks, where gas exchange with blood occurs. The oxygen levels stay high in the alveoli, so that the oxygen diffuses into the blood and vice versa with CO2.
What are alveoli mainly made of?
Type 1 and Type 2 pneumocytes.
What do type 1 pneumocytes do?
They are flat & thin cells that minimize diffusion distance to capillaries.
Which pneumocyte can differentiate, which can’t?
Tyoe 2 can, type 1 cannot.
What is the purpose of the fluid on the alveoli?
It’s easier for oxygen to diffuse across the membrane when dissolved in a liquid.
What do type 2 pneumocytes do?
They secrete a surfactant, which breaks the surface tension of the fluid on the alveoli, because otherwise the alveoli might not inflate as much.
How is the size of different alveoli managed?
Alveoli with smaller SA have a higher surfactant density, so they inflate faster, until they have the same surfactant density as larger alveoli and then they inflate at the same rate.
What is the name of the muscles between the ribs?
Intercostal muscles
What happens during inhalation?
The diaphragm contracts (downwards), the external intercostal muscles contract, so the volume of the lungs increases, which decreases the pressure in the lungs and thus air rushes in.
What happens during exhalation?
the diaphragm relaxes, the intercostal muscles contract, so the volume decreases, which increases the pressure and air rushes out. Also, the abdominal muscles contract and push the diaphragm upwards.
What causes emphysema?
The alveolar walls get damaged, which causes the alveoli to lose elasticity and, and thus the walls can rupture, making holes, which decreases SA for gas exchange. The chemicals in smoking often irritate the alveolar walls.
What is tidal volume? What is the ventilation rate?
Tidal volume= volume of air you get into lungs during one breath
Ventilation rate= breaths per minute
both increase during excercising
