Bio Nerve Question

[FutureDoc01]

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Which of the following cell types most likely contain adrenergic receptors( respond to epinephrine)?

A. Chromaffin cells
B. Sympathetic Post ganglionic neurons
C. Parasympathetic post ganglionic neurons
D. Cardiac Muscle


Why is the answer D and not B. I'm probably making this harder than it needs to be....

 

[PiBond]

sympathetic postganglionic neurons respond to ACh (as do parasympathetic post ganglionic neurons) and thus have cholinergic receptors. the heart responds to epi by increasing its rate and force of contraction

 

[ilovemcat]

sympathetic postganglionic neurons respond to ACh (as do parasympathetic post ganglionic neurons) and thus have cholinergic receptors. the heart responds to epi by increasing its rate and force of contraction

All pre-ganglionic neurons release ACH (acetycholine) and respond to Cholinergic receptors. Only the post-ganglionic neurons of the sympathetic system release norepinephrine/epinephrine which bind to adrenergic receptors. Both norepinephrine/epinephrine are released from the adrenal medulla (above the kidney), hence the name of the receptor they bind to.

 

[RogueUnicorn]

.

 

[AliDeLaLouisa]

The adrenergic receptors (or adrenoceptors) are a class of G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline (norepinephrine) and adrenaline (epinephrine). Although dopamine is a catecholamine, its receptors are in a different category.
Many cells possess these receptors, and the binding of an agonist will generally cause a sympathetic response (e.g. the fight-or-flight response). For instance, the heart rate will increase and the pupils will dilate, energy will be mobilized, and blood flow diverted from other non-essential organs to skeletal muscle. The question causes you to think what would happen? heart reate increase--> Cardiac muscles. Yes this a paart of the sympathetic system.....

 

[kentavr]

Let's say you didn't know all the right stuff above. Didn't you see pulp fiction or any other movie with direct injection to the heart? What they administer? EPI. Here is your answer. I guess in MCAT all tools are good. (if they are right) 🙂

 

[RogueUnicorn]

preganglionic is not even in the answer choices, why is it being brought up? plenty of neuronal tissue contain catecholamine receptors, and there's evidence that there are adrenergic receptors in SNS preganglionic cells... no need to complicate the issue.

 

[kentavr]

gujuDoc, sorry for confusion, my comment was addressed to topic starter. I have no objections to your explanations except, that asthma is not a good example. In asthma the stimulation of the heart rate by epi actually considered as a side effect. so it is not recommended for use in asthma. If I am not mistaken all inhalers with epi will be out of market by 2011. You probably confused asthma with anaphylactic shock where epinephrine is used. Such as acute allergic reactions, insect bites reactions etc. However, even there, the heart rate is a side effect: Vasoconstrictor and Bronchodilator are two main properties of EPI used in this case. I hope all that is beyond the MCAT.