Human Anatomy and Physiology : Help with Parasympathetic Postganglionic Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #1 : Parasympathetic Nervous System

Which of the following statements is true concerning the autonomic nervous system?

Possible Answers:

The autonomic nervous system is voluntarily controlled

Both the sympathetic and parasympathetic divisions use epinephrine

Parasympathetic postganglionic neurons are found closer to the effector than sympathetic postganglionic neurons

The cranial nerves are considered part of the autonomic nervous system

Only the parasympathetic division has signals originating from the spinal cord

Correct answer:

Parasympathetic postganglionic neurons are found closer to the effector than sympathetic postganglionic neurons

Explanation:

The autonomic nervous system can be divided into the sympathetic and parasympathetic nervous systems. Although both divisions have target organs and tissues, the parasympathetic postganglionic neurons are usually much closer to the effector organ than sympathetic postganglionic neurons.

The autonomic nervous system is under involuntary control, while the somatic nervous system is under voluntary control. Only sympathetic postganglionic neurons use epinephrine; most autonomic neurons use acetylcholine. Both divisions include neurons that originate from the spinal cord. The cranial nerves have both sensory and motor functions, meaning that they can be involved in either somatic or autonomic innervation.

Example Question #6 : Peripheral Nervous System

Which cranial nerves are part of the visceral efferent parasympathetic in the peripheral nervous system (PNS)?

Possible Answers:

III, VII, IX, and XI

VII, IX, and X

III, VII, IX, and X

III, VII, VIII, and IX

VII and IX

Correct answer:

III, VII, IX, and X

Explanation:

The cranial nerves that are part of the visceral efferent parasympathetic in the PNS are III, VII, IX, and X. Cranial nerve III (oculomotor) travels to the ciliary ganglion and supplies the pupil of the eye for constriction. Cranial nerve VII (facial) travels to the pterygomandibular and submandibular ganglion and supplies the lacrimal and salivary glands. Cranial nerve IX (glossopharyngeal) travels to the otic ganglion and supplies the Parotid gland. Lastly, cranial nerve X (vagus) travels to the Prevertebral plexus and thoracic plexus in order to supply the gut, heart, and enteric system.

Example Question #7 : Peripheral Nervous System

Atropine is a molecule that is an antagonist to muscarinic cholinergic receptors. Based on your knowledge of autonomic nervous system physiology, how would you expect the pupils to respond to topical administration of atropine?

Possible Answers:

You will observe mydriasis (pupil dilation)

The iris sphincter muscles would experience a relaxed paralysis

The iris sphincter muscles would experience a contracted paralysis

There will be no change in pupil size because the pupils do not have muscarinic receptors

You will observe miosis (pupil constriction)

Correct answer:

You will observe mydriasis (pupil dilation)

Explanation:

The pupillary sphincter muscles contain muscarinic cholinergic receptors that help the eyes to respond to parasympathetic tone. When this parasympathetic signal is blocked (antagonized) via atropine, you will observe a "sympathetic response" at the level of the pupil. In this scenario, you would observe the sympathetic response of pupil dilation. Hint: "aTROP'ine" and "seeing a TROPical setting" both cause your pupils to dilate nice and wide!

Example Question #8 : Peripheral Nervous System

Which of these is a feature of the parasympathetic nervous system?

Possible Answers:

Parasympathetic stimulation causes dilation of blood vessels in the skin of the limbs

Some parasympathetic fibers pass through the paravertebral ganglia, others synapse there

The parasympathetic nervous system does not involve the spinal cord or spinal nerves

Some parasympathetic fibers leave the CNS by specific cranial nerves

Correct answer:

Some parasympathetic fibers leave the CNS by specific cranial nerves

Explanation:

The parasympathetic nervous system conserves energy and is thus know as the "rest and digest" system. It slows heart rate, increases salivation, lacrimation, urination, deification, digestion, and sexual arousal. The nerves of the parasympathetic system arise in the CNS. Specific nerves include cranial nerves, including the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve.

In the sympathetic nervous system some sympathetic fibers pass through the paravertebral ganglia, and others synapse there.

Example Question #1 : Help With Parasympathetic Postganglionic Physiology

Which of the following nerves carries parasympathetic nerve fibers?

Possible Answers:

Sympathetic trunk

Vagus nerve

C3, C4, and C5 spinal nerves

White ramus communicans

Correct answer:

Vagus nerve

Explanation:

The vagus nerve (CNX) provides the heart and digestive tract with parasympathetic ("rest and digest") control.

Cranial nerves with associated parasympathetic activity include CN III, VII, IX, and X. The sympathetic trunk and the white ramus communicans are associated with the sympathetic nervous system. 

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