Dr Gawad Physiology Course Online Exams - Ans Introduction, Autonomic Ganglia

The autonomic nervous system differs from the somatic nervous system in having a connector neuron (preganglionic neuron) that comes outside the central nervous system and a postganglionic neuron that supplies the organ. This is in contrast to the somatic nervous system, which does not have this type of connector neuron. The autonomic nervous system is responsible for regulating involuntary bodily functions, such as heart rate, digestion, and breathing, while the somatic nervous system controls voluntary movements of skeletal muscles.

The sympathetic preganglionic nerve fibers are myelinated nerve fibers. These fibers originate at the autonomic ganglia and relay in the sympathetic chain. They show minimal divergence in the autonomic ganglia, meaning that they have a more direct and specific pathway compared to other nerve fibers.

The autonomic ganglia do act as distributing centers, as they receive signals from the preganglionic fibers and transmit them to the postganglionic fibers. There are indeed three types of autonomic ganglia: sympathetic ganglia, parasympathetic ganglia, and enteric ganglia. The chemical transmitter used by the autonomic ganglia is not acetylcholine, but rather norepinephrine for sympathetic ganglia and acetylcholine for parasympathetic ganglia. The preganglionic fibers do not pass through the autonomic ganglia without relay, as they synapse with the postganglionic fibers within the ganglia. Therefore, the correct answer is "None of the above."

The flexion of the arm following a painful stimulus is not an autonomic reflex action. Autonomic reflex actions are involuntary and controlled by the autonomic nervous system, which regulates bodily functions such as heart rate, digestion, and urination. The flexion of the arm in response to pain is a somatic reflex action, controlled by the somatic nervous system, which governs voluntary movements.

The autonomic ganglia are not relay stations for all preganglionic fibers passing through them. While they do serve as relay stations for some preganglionic fibers, not all fibers pass through the ganglia. Some preganglionic fibers bypass the ganglia and synapse directly with postganglionic neurons. Therefore, this statement is not true.