Why is it better that the lungs are spongy rather than empty like a balloon?

Which type of neuroglia is found outside of the brain?

Witch type of microscope is used to view very small cell components like proteins and dna?

An example of internal feedback working to maintain homeostasis is your a. decreased respiration rate when you are studying b. decreased heart rate when you are sad c. increased respiration rate when your muscles need more oxygen d. increased heart rate when your lungs need more oxygen