Solution. 1  This species has a 2â charge on it, so it is an anion. Anions are named using the stem of the element name with the suffix -ide added. 2  Because this species has no charge, it is an atom in its elemental form. This is cobalt. 3  In this case, there is a 2+ charge on the atom, so it is a cation.
1. 2. 3. The walls of the alveoli are composed of a single layer of flattened epithelial cells, as are the walls of the capillaries, so gases need to diffuse through just two thin cells. The alveoli walls are kept moist by water diffusing from the surrounding cells.he walls of the alveoli are composed of a single layer of flattened epithelial cells, as are the walls of the capillaries, so gases need to diffuse through just two thin cells. The alveoli walls are kept moist by water diffusing from the surrounding cells.
76. alveolar sac. A cluster of alveoli located at the end of each alveolar duct in the lungs; each of the alveoli is a tiny, thin-walled, capillary-rich sac, lined by a simple squamous epithelium, where the exchange (diffusion) of oxygen and carbon dioxide (and other less important gases) takes place.he squamous epithelial cell forming the alveolar wall and through whose cell membranes and cytoplasm the exchange of oxygen and carbon dioxide (and other less important gases) takes place; collectively they cover 95% of the alveolar surface area.