Peripheral Nervous System Flashcards

Flashcards covering the key topics in the Peripheral Nervous System, including sensory receptors, nerve structure, cranial and spinal nerves, nerve plexuses, motor endings, and reflex arcs.

What are the four main components of the Peripheral Nervous System (PNS)?

Sensory receptors, afferent nerves, efferent nerves, and motor endings.

What is the function of sensory receptors in the PNS?

To respond to changes in the environment (stimuli) and initiate graded potentials.

Name the five classifications of sensory receptors based on the type of stimulus they respond to.

Mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, and nociceptors.

How are exteroceptors classified based on location and stimulus?

Located at or near the body surface, respond to external stimuli (touch, pressure, pain, temperature, special senses).

How are interoceptors/visceroceptors classified based on location and stimulus?

Internal, respond to internal stimuli (viscera, blood vessels, etc.) such as stretch, pain, temperature, and chemical changes.

What is the function of proprioceptors, and where are they located?

Respond to internal stimuli related to body position; located in skeletal muscles, tendons, joints, and ligaments.

What is the main difference between simple and complex sensory receptors?

Simple receptors are modified dendritic endings of sensory neurons; complex receptors involve multiple cell types and sensory organs (e.g., eyes, ears).

List the three connective tissue wrappings of a nerve.

Endoneurium, perineurium, and epineurium.

What is the difference between sensory/afferent nerves and motor/efferent nerves?

Sensory nerves carry information to the CNS, while motor nerves carry information from the CNS.

How many pairs of cranial nerves are there, and where do they primarily serve?

There are 12 pairs of cranial nerves, mostly serving the head and neck.

List the three things to know for each cranial nerve.

Name, Roman numeral, Type (Sensory or Motor), and Primary function

I

Olfactory: Sensory, Smell

II

Optic: Sensory, Vision

III

Oculomotor: Motor, Eye movements

IV

Trochlear: Motor, Eye movements

V

Trigeminal: Mixed, Face, chewing

VI

Abducens: Motor, Eye movments

VII

Facial: Mixed, Taste, glands, expressions

VIII

Vestibulocochlear: Sensory, Hearing, balance

IX

Glossopharyngeal: Mixed, Taste, swallowing & salivary

X

Vagus: Mixed, Pharynx, larynx, viscera

XI

Accessory: Motor, Neck & upper back

XII

Hypoglossal: Motor, Tongue

How many pairs of spinal nerves are there, and where do they exit the spinal column?

31 pairs, exiting through intervertebral foramina.

What type of nerves are spinal nerves, and how are they formed?

All spinal nerves are mixed type, formed by dorsal and ventral roots of the spinal cord.

What are the dorsal and ventral rami of spinal nerves, and what do they serve?

Dorsal rami serve the skin and muscles of the posterior trunk; ventral rami form networks (plexuses) for the anterior body.

What is a nerve plexus?

A plexus is a network formed by multiple ventral rami that give rise to individual spinal nerves.

Name the four spinal nerve plexuses.

Cervical, brachial, lumbar, and sacral.

What is the major function of the cervical plexus, and which nerve is of particular importance?

Primarily cutaneous nerve innervation of the neck and shoulder; the phrenic nerve, which supplies the diaphragm, is especially important.

What is the function of the brachial plexus?

Gives rise to virtually all nerves that innervate the upper limbs.

Name four major nerves that arise from the brachial plexus.

Axillary, radial, median, and ulnar nerves.

What are the major branches of the lumbar plexus responsible for innervating?

Descend to innervate the anterior and medial thigh.

Which areas do the branches of the sacral plexus serve?

Buttocks, lower limbs, pelvic structures, and perineum.

What is the sciatic nerve, and which areas does it innervate?

The thickest and longest nerve in the body, it innervates the posterior thigh and supplies all of the lower limb except the anteromedial thigh.

Define dermatomes and their significance.

Cutaneous branches of each spinal nerve that innervate all areas of the skin.

Where can ACh and NE be found as neurotransmitters?

ACh is the neurotransmitter in SOMATIC NS, and ACh or NE in the AUTONOMIC NS

What is the key difference between parasympathetic and sympathetic nerves?

Parasympathetic nerves are for routine daily activities and relaxation ("rest and digest"), while sympathetic nerves are for vigorous exercise and emergency response ("fight or flight").

What are the components of the reflex arc?

Receptor, sensory/afferent neuron, integration center (usually with an interneuron), motor/efferent neuron, and effector.

What are the typical classifications of Reflex Activity?

Somatic (activate skeletal muscle) and Autonomic (activate visceral effectors)