Final answer:
The two types of cellular communication that involve hormones but don't enter the bloodstream are autocrine and paracrine signaling. Autocrine signaling occurs within the same cell, while paracrine signaling acts on nearby cells.
Step-by-step explanation:
The two types of cellular communication that involve hormones but don't enter the bloodstream are autocrine and paracrine signaling.
Autocrine signaling occurs when a cell releases a signaling molecule that binds to receptors on its own cell surface, leading to a response within the same cell. An example of autocrine signaling is the secretion of interleukin-1 (IL-1) by immune cells, which then bind to receptors on the same immune cells, inducing an inflammatory response.
Paracrine signaling, on the other hand, involves the release of signaling molecules that act on nearby cells. These molecules diffuse through the extracellular matrix and elicit quick, localized responses. An example of paracrine signaling is the release of growth factors by cells to promote the growth and development of neighboring cells.