People who don't believe in mental illnesses think the person with the mental illness is just lying about it. people may not believe in them because it's not like a physical illness where you see the symptoms or you clearly see that the person is sick. it's just the matter of not seeing physical proof of the mental illness.
The alveoli is where the oxygen moves out of the lungs and into the blood. At the same time carbon dioxide moves out of the blood and into the lungs to be exhaled.
