交感神经系统节前纤维：

Question

交感神经系统节前纤维：

BlackTom AI · Accepted Answer

The question provided is: '交感神经系统节前纤维：' which asks about the nature or targets of sympathetic preganglionic fibers. However, no answer options were supplied in the data, so there are no alternative statements to evaluate one by one.

To build understanding from first principles: sympathetic preganglionic neurons are cholinergic, meaning they release acetylcholine (ACh) onto nicotinic acetylcholine receptors. The classic site of these synapses is the autonomic ganglia, where ACh binds to neuronal nicotinic receptors on postganglionic neurons. This is the general mechanism by which preganglionic sympathetic fibers influence postganglionic neurons.

A distinctive and notable exception in the sympathetic system is the adrenal medulla. Here, preganglionic sympathetic fibers form synapses directly onto chromaffin cells of the adrenal medulla, which also possess nicotinic receptors. Activation of these receptors leads to release of epinephrine (and some norepinephrine) into the bloodstream, rather than a direct synapse onto a postganglionic neuron.

Given the absence of alternative choices, there is nothing to critique column-wise. If an option list were present, we would evaluate each choice against this framework:
- If an option states that preganglionic sympathetic fibers synapse on autonomic ganglia via nicotinic receptors, that would align with standard physiology.
- If an option claims non-cholinergic transmission (e.g., using a different neurotransmitter) at the ganglionic level, that would be incorrect.
- If an option mentions direct adrenal medulla innervation with nicotinic receptors, that would be correct as a special case of preganglionic sympathetic output.
- Any option suggesting that preganglionic fibers terminate at targets other than ganglia or adrenal medulla (e.g., directly at smooth muscle or heart without a ganglionic relay) would be inaccurate for classic sympathetic pathways.

In summary, the typical depiction is that sympathetic preganglionic fibers are cholinergic and form nicotinic receptor-mediated synapses in autonomic ganglia, with a special adrenal medulla innervation via nicotinic receptors. The adrenal medulla response is a key exception where preganglionic fibers act on chromaffin cells rather than a postganglionic neuron.

PCOL2021（ND）

交感神经系统节前纤维：

View Explanation

Log in for full answers

Similar Questions

The largest number of parasympathetic nervous system fibers are contained in which area of the body?

Question at position 39 The pontine storage center facilitates the storage of urine by enhancing Printed Blank[input]Question Blank 1 of 1[input] activity to keep the internal urethral sphincter contracted.parasympatheticsympathetic

Question at position 44 What causes dry mouth during public speaking or stressful events?Dehydration aloneOverproduction of saliva due to anxietyIncreased sympathetic stimulationIncreased parasympathetic activity

The autonomic nervous system:

Question at position 1 The parasympathetic nervous system's effect on the heart would be __________. Select all that apply.Cardiac output would increaseStroke volume would increaseStroke volume would decreaseCardiac output would decreaseHeart rate would increaseHeart rate would decrease

Question at position 12 True or false: Mr. Gomez's HR was elevated due to sympathetic nervous stimulation trying to increase CO.TrueFalse

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler