Chapter 16, Problem 1RAC

Given these phrases:
(1) neuron cell bodies in the nuclei of cranial nerves
(2) neuron cell bodies in the lateral gray horn of the spinal cord
(T1-L2 and S2-S4)
(3) two synapses between the CNS and effectors
(4) regulates smooth muscle
Which of the phrases are true for the autonomic nervous system?
a. 1,3  b. 2,4  c. 1,2,3  d. 2,3,4  e. 1,2,3,4

Summary Introduction

Introduction:

The autonomic nervous system controls the unconscious movement of the body. It has two important divisions’ sympathetic and parasympathetic divisions. They are present on the preganglionic neuron of the CNS and autonomic ganglia of the PNS. The sympathetic axons travel through the sympathetic chain ganglia to their target cell. A ganglion is nerve cell bodies which are connected to one another in a series and form plexus.

Answer to Problem 1RAC

The correct answer is option (e) 1,2,3,4.

Explanation of Solution

Explanation/justification for the correct answer:

Option (e).1,2,3,4. All the given option is true for autonomic nervous system. The axon of the parasympathetic preganglionic neuron cell bodies is present in the cranial nerves. The lateral gray horn is a motor neuron fiber of the spinal cord that connects two sides of cord, dorsal and ventral ganglia. There are two synapses between the CNS and effectors Ach at the first synapse and Ach or norepinephrine at the second synapse. It helps in regulating smooth muscle contraction. So, the correct answer is option (e).

Explanation for incorrect answer:

Option (a).1,3. This option is not appropriate because the statement second and fourth is also true. The lateral gray horn from T1 − L2 is present in the sympathetic division and S2- S4 is located in the parasympathetic division. The sympathetic division of the ANS helps in regulating smooth muscle contraction.

Option (b).2,4. This option is not correct because the axon of the parasympathetic preganglionic neuron cell bodies is present in the nuclei of cranial nerves of the CNS which helps in regulating the ANS activity. There are two synapses one at the end of each neuron, first in the CNS and second in the ganglion.

Option (c).1,2,3. This is an invalid option because the fourth statement is also correct, the sympathetic division of the autonomic nervous system helps in regulating the contraction of the smooth muscle of the target organ.

Option (d).2,3,4. This option is not appropriate because the first statement is also true, The lateral gray horn from T1−L2 is present in the sympathetic division and S2-S4 is located in the parasympathetic division.