If sympathetic and parasympathetic neurons both release acetylcholine (ACh), how can they have antagonistic effects? (Check all that apply.)

Question

_____  The target cells of each set of neurons respond differently to the same signal.
_____  Each type of neuron secretes ACh bound to a different co-neurotransmitter.
_____  Sympathetic neurons activate the adrenal gland, causing secretion of epinephrine.
_____  The neurons release different forms of ACh.
_____  Parasympathetic neurons activate the adrenal gland, causing secretion of epinephrine.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
 
Gather Content/Choose Answer
· What do you already know about the sympathetic and parasympathetic systems? What other information is related to the question?
 
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

__X__  The target cells of each set of neurons respond differently to the same signal.
_____  Each type of neuron secretes ACh bound to a different co-neurotransmitter.
__X__  Sympathetic neurons activate the adrenal gland, causing secretion of epinephrine.
_____  The neurons release different forms of ACh.
_____  Parasympathetic neurons activate the adrenal gland, causing secretion of epinephrine.

Clarify Question
· What is the key concept addressed by the question?
        o How can systems that have opposite effects be controlled by the same neurotransmitter?
· What type of thinking is required?
        o This is an analyze question because you have to determine the mechanism of opposite outcomes resulting from the release of the same neurotransmitter (ACh).
 
Gather Content/Choose Answer
· What do you already know about the sympathetic and parasympathetic systems? What other information is related to the question?
         o To solve this problem, you’ll need to know that the sympathetic and parasympathetic systems have opposite physiological effects. For example, activation of the sympathetic system increases heart rate while the parasympathetic system slows it down. While both systems release ACh, the sympathetic system activates the adrenal gland to secrete epinephrine. ACh release in the parasympathetic division slows the heart, increases secretions and activities of the digestive system, while the ACh-mediated release of epinephrine has the opposite physiological effects.
 
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?
        o If you figured out the correct answer, great! If not, where did you go wrong? Did you remember that neurons often release more than one neurotransmitter? That is correct, but these co-transmitters are not bound together (answer B). Did you think that there are different forms of ACh (answer D)? It is true that there are different types of ACh receptors, but only one form of ACh. Were you confused about which division of the autonomic nervous system activates the adrenal gland? It is the sympathetic neurons that activate it, not parasympathetic neurons.