A classic, life science-themed fluid dynamics scenario is blood flow through a constriction. Physics teachers traditionally ask students if the pressure experienced by the blood in the constriction is greater, lesser, or the same as before the constriction. The conventional approach to resolving this question calls upon the equation of continuity, as well as the Bernoulli equation. Biological systems, however, experience a resistance to flow, and a consequential pressure drop, that is often better described by Poiseuille's law. Within this apparent conflict, which approach is correct? This paper argues that Poiseuille's law is the more appropriate choice for most biological examples and encourages a Poiseuille-first approach to teaching fluid dynamics in classes designed for life science majors.