Preganglionic neurotransmitter in sympathetic division of autonomic nervous system is: March 2013
**Core Concept**
The autonomic nervous system (ANS) is a complex system controlling involuntary functions, divided into sympathetic and parasympathetic divisions. The sympathetic division is responsible for the 'fight or flight' response, whereas the parasympathetic division promotes 'rest and digest' activities. Neurotransmitters play a crucial role in transmitting signals between neurons.
**Why the Correct Answer is Right**
The preganglionic neurons in the sympathetic division release acetylcholine (ACh) as their primary neurotransmitter. This is in contrast to the postganglionic neurons, which release norepinephrine (NE) or epinephrine (Epi). The release of ACh from preganglionic neurons triggers a cascade of events, ultimately leading to the release of NE or Epi from postganglionic neurons. This complex process is mediated by various receptors, including muscarinic and nicotinic receptors.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately represent the primary neurotransmitter released by preganglionic neurons in the sympathetic division.
**Option B:** This option is incorrect because it is associated with the parasympathetic division, not the sympathetic division.
**Option C:** This option is incorrect because it is associated with the postganglionic neurons in the sympathetic division, not the preganglionic neurons.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the neurotransmitters released by preganglionic and postganglionic neurons in the sympathetic division are different. This knowledge is crucial for understanding various clinical scenarios, such as the effects of certain medications on the ANS.
**Correct Answer: C. Acetylcholine**