MICROANATOMY

Detailed explanation-1: -External respiration, also known as breathing, involves both bringing air into the lungs (inhalation) and releasing air to the atmosphere (exhalation). During internal respiration, oxygen and carbon dioxide are exchanged between the cells and blood vessels.

Detailed explanation-2: -External respiration occurs in the alveoli. To fully define external respiration, we need to know which way the gases are diffusing. Oxygen flowing in from the air diffuses from the alveoli into the blood. Carbon dioxide from the blood diffuses into the alveoli where it can be released during exhalation.

Detailed explanation-3: -External respiration occurs as a function of partial pressure differences in oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries.