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In what direction does CO2 and 02 diffuse in gas exchange?

CO2 diffuses from plasma to alveolus
O2 diffuses from the alveolus to red blood cells


What is ventilation?

Physical process of breathing in and out


What is gas exchange?

Gas diffusion in alveoli


What is respiration?

The release of energy inside cells


How is a concentration gradient maintained in gas exchange?

Air in the alveolus has a higher concentration of O2 and a lower concentration of CO2 than the blood in the capillary.


What are the properties of type 1 pneumocytes?

They have a thin lining for efficient gas exchange and 0.15um of cytoplasm


What are the properties of type 2 pneumocytes?

They are thick and spherical, secretes fluid ( surfactant)to moisten alveoli, speeding up diffusion and prevents walls sticking together. They make up 5% of surface.


What are the stages of inspiration?

Pressure decreases. Volume increase. Rib cage moves up and out. External intercostal muscles contract and internal intercostal muscles relax. Diaphragm contracts and flattens and abdominal muscles relax.


What are the stages of expiration?

Pressure increases. Volume decreases. Rib cage moves in and down. External intercostal muscles relax and internal intercostal muscles contract. Diaphragm relaxes and domes up. Abdominal muscles contract.


What are the symptoms of lung cancer?

Difficulties with breathing, persisten coughing and coughing up blood. Chest pain. Loss of appetite, weight loss, general fatigue.


What happens in emphysema?

Thin walled alveoli is replaced by a small number of larger air sacs with thicker walls. The surface area for gas exchange is reduced- lungs become less elastic and ventilation is difficult. Phagocytes inside alveoli normally prevent lung infections by engulfing bacteria and producing elastase to kill them inside vesicles.