Natural Selection describes how species have evolved differentially, but it is descriptive, non-mechanistic. What mechanisms does Nature use to accomplish this feat? One known way in which ancient natural forces affect development, phylogeny and physiology is through gravitational effects that have evolved as mechanotransduction, seen in the lung, kidney and bone, linking as molecular homologie...

Growing literature suggests important sex-based differences in outcome following traumatic brain injury (TBI) in animals and humans. Progesterone has emerged as a key hormone involved in many potential neuroprotective pathways after acute brain injury and may be responsible for some of these differences. Many studies have utilized supraphysiologic levels of post-traumatic progesterone to revers...

Physiology in microgravity is a challenging field of research because of limited resources. Though humans have been in space for 50 years most meaningful data has been collected only within the last 15 years. While expensive studies with small sample sizes make obtaining and interpreting data difficult, some general conclusions about the human physiological response to microgravity can be drawn...

Owing to multiplanar imaging capabilities and excellent tissue characterization, MRI can facilitate definitive diagnosis of benign conditions of the female pelvis. The purpose of this chapter is to review the spectrum of common benign conditions of the female pelvis and to illustrate the MRI features of these conditions, with an emphasis on the key imaging characteristics to suggest accurate di...

Anatomic and Physiologic Considerations Nerve fibers subserving the sense of smell have their cells of origin in the mucous membrane of the upper and posterior parts of the nasal cavity (superior turbinates and nasal septum). The entire olfactory mucosa covers an area of about 2.5 cm2 and contains three cell types—the olfactory or receptor cells (which number between 6 and 10 mil l ion in each ...