5Environmental Response and Homeostasis
In Chapters 1–4, we learned that in living organisms, membranes separate cellular content from the external environment, traits and genes are passed to the next generation by proliferation and reproduction, and metabolism helps in sustenance. Using vertebrates as examples, this chapter deals with environmental responses and homeostasis, which are important attributes differentiating animate objects from inanimate ones. Organisms have the ability to appropriately respond to changes in their external environment, such as temperature, atmospheric pressure, and osmotic pressure, in order to maintain homeostasis of their internal environment. To use this ability to the greatest extent possible, the nervous and endocrine systems function together in a concerted manner, both temporally and spatially. This chapter seeks to study the complexities and wonders of life by understanding the mechanisms underlying homeostasis.