If blood transports hormones throughout the body, how do they communicate with specific targets?

Question

A.  Special gateway valves in the blood vessels direct hormones to their target tissues.
B.  Special carrier proteins "walk" along microtubule tracts to deliver the hormones to their targets.
C.  Axonal pathfinding mediates the delivery of hormones to their specific targets.
D.  Only target tissues have receptors that allow them to receive the signal.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about hormones? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  Only target tissues have receptors that allow them to receive the signal.

Clarify Question
What is the key concept addressed by the question?
        · How do hormones target part of the body?
What type of thinking is required?
            o This is an analyze question because you have to consider each answer for accuracy in describing how hormones deliver their signals to the appropriate target tissues.

Gather Content
What do you already know about hormones? What other information is related to the question?
        · Hormones deliver their signals through the bloodstream. As blood travels to all tissues, why don’t the hormones equally affect all tissues? It is because only tissues which express the receptors for the hormone will allow the hormone to bind and transmit the signal inside the cell.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · There are no special gateway valves in blood vessels to direct hormones to their target tissues. This would not work since multiple hormones are diffuse across all the blood, so it would be impossible to shunt blood with one hormone one direction and another hormone to another tissue. As blood flows rather quickly, there is no need for carrier proteins to move along microtubule tracks to deliver hormones. Axonal pathfinding and transport only deals with neural tissue and hormones can affect all tissue types. Thus, the answer must be that only target tissues have receptors that allow them to receive the signal.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
       · Answering this question correctly depended upon understanding that differential expression of receptors is how hormones communicate with specific targets. If you got the answer correct, wonderful! If not, which answer did you choose? Did you know that hormones bind to receptors but not realize that receptors for specific hormones are only expressed in specific tissues?