Consider this microscopic image of bacteria. mc005-1.jpg which bacterial shape is shown in the image?

hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: