6.4 Gas exchange Flashcards
What does ventilation maintain?
Ventilation maintains the concentration gradient necessary for passive diffusion.
What is ventilation?
Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.
What is gas exchange?
All organisms absorb one gas form the environment and release a different one.
What is respiration?
The controlled release of organic compounds to form ATP.
Explain why a ventilation system is needed to maintain a concentration gradient.
A ventilation system is needed to maintain a concentration gradient within the alveoli so that diffusion can diffuse into the air sacs and diffuse carbon dioxide out.
What are pneumocytes?
Pneumocytes are alveolar cells.
What do pneumocytes do?
Pneumocytes line the alveoli and comprise the majority of the inner surface of the lungs.
What is the function of Type 1 Pneumocytes?
Type 1 pneumocytes are involved in gas exchange between alveoli and capillaries. They are extremely thin and minimise gas diffusion distances.
What is the function of Type 2 pneumocytes?
Type 2 pneumocytes are responsible for the secretion of pulmonary surfactant. This creates a moist surface that reduces surface tension. This prevents sides of alveoli from adhering to each other.
What is the function of the pulmonary surfacant?
The pulmonary surfactant creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other.
What are the features of Type 1 Pneumocytes?
Type 1 pneumocytes are extremely thin alveolar cells adapted to carry out gas exchange. They are flattened cells. Most cells in the epithelium are type 1 pneumocytes.
What are the features of Type 2 pneumocytes?
Type 2 pneumocytes are rounded cells. 5% of cells in epithelium are type 2. They secrete a fluid which coats the inner surface of the alveoli.
What happens during inhalation?
In inhalation:
- The diaphragm moves downwards and flat.
