Answer:
Valence electrons, or the electrons that are farthest from the nucleus.
Answer:
The function of the pleura is to allow optimal expansion and contraction of the lungs during breathing. The pleural fluid acts as a lubricant, allowing the parietal and visceral pleura to glide over each other friction free. This fluid is produced by the pleural layers themselves.
Human red blood cells are formed mainly in the bone marrow and are believed to have an average life span of approximately 120 days<span>.</span>
