Question

Select ALL of the following which are TRUE about the parasympathetic nervous system (hint- there are 4):

Group of answer choices

parasympathetic influence causes blood vessels to constrict

preganglionic axons are generally longer than post-ganglionic axons

preganglionic axons emerge from thoracic and lumbar nerves

preganglionic axons secrete Ach; post-ganglionic axons secrete NE

preganglionic neurons emerge from cranial and sacral nerves

both preganglionic and post-ganglionic axons secrete Ach

parasympathetic influence causes an increase in digestive motility and secretions

Answer 1

Correct statements -

• Preganglionic axons are generally longer than post-ganglionic axons
• preganglionic neurons emerge from cranial and sacral nerves
• Both preganglionic and post-ganglionic axons secrete Ach
• parasympathetic influence causes an increase in digestive motility and secretion.

Incorrect statements -

• Parasympathetic influences cause blood vessels to constrict.
• preganglionic axons emerge from thoracic and lumbar nerves
• preganglionic axons secrete Ach; post-ganglionic axons secrete NE

EXPLANATION :

**Parasympathetic nervous system exerts little or no effect on blood vessels. However in coronary arteries they cause vasoconstriction . Salivary glands, genital erectile tissue and gastrointestinal glands are also innervated by parasympathetic system, where they cause vasodilatation.

** Parasympathetic system has two neurons involved in transmission of impulses from their source to effector organ :- preganglionic and post ganglionic

Both preganglionic and post ganglionic have same neurotransmitter - acetylcholine.

Preganglionic axons are longer as they originate from cranial nerves and sacral segments.Whereas post ganglionic axons originate from the ganglia near to the effector organ or from the walls of effector organ.