Cell Communication: Direct, Local, Endocrine Signaling

Hi, everybody. Welcome back. This is Mr. Poser, your AP Biology

teacher and today we are starting Topic 4.1, which is on Cell Communication and

thus, by extension, we are starting Unit 4, which is on Cell

Communication and the Cell Cycle. So the first part of the unit is gonna be about cells communicating,

uh, we're gonna be talking about signals and signal transduction and what that is,

how a cell takes a message from the outside and, uh, does something,

um, in response to that signal. Um, and today we're

gonna be talking about the different ways that those signals can be transmitted. Um,