Week 3: Peripheral Nervous System

Question 1

________ are scattered profusely throughout the body. They are biological transducers, in which physical or chemical stimuli create action potentials in nerve endings.

a. General sensory endings
b. Motor endings
c. Peripheral endings
d. Autonomic ganglia

Answer 1

a. General sensory endings

Question 2

_________ are terminal branches of the axon that may either be closely applied to cells or lie freely in the extracellular spaces of connective tissue.

Answer 2

Non-encapsulated endings

Question 3

Sensory receptors respond to (select all that apply):

a. Pain
b. Touch
c. Pressure
d. Temperature

Answer 3

a. Pain
b. Touch
c. Pressure
d. Temperature

Question 4

Which of the following are located in muscles, tendons, and joints?

a. Exteroceptors
b. Interoceptors
c. Proprioceptors

Answer 4

Proprioceptors

where they provide data or information for reflex adjustments of
muscle action and for awareness of position and movement.

Question 5

What is the external diameter (micrometers) of A alpha (AI) fibers?

a. 19 - 24
b. 12-20
c. 10-15
d. 5-15
e. 3-8
f. 1-3

Answer 5

b. 12-20

Question 6

Functionally different sensory endings are supplied by fibers of specific sizes. Why?

Answer 6

Size is important because there is a correlation between fiber diameter and the rate of conduction of the action potential.

Question 7

List the four major groups of non-encapsulated cutaneous sensory endings.

Answer 7

Cutaneous plexuses
Free nerve endings
Merkel endings
Peritrichial nerve endings

Question 8

List the three cutaneous plexuses

Answer 8

1. The subcutaneous plexus
2. The dermal plexus
3. The papillary plexus

Question 9

What are interoceptors?

Answer 9

They are sensory endings found in the viscera (the internal organs in the main cavities of the body). They are adapted for central
conduction which occurs through primary sensory neurons.

Question 10

The ____________ lies within the densely collagenous reticular layer that constitutes the deeper part of the dermis

Answer 10

The dermal plexus

Question 11

What is the external diameter (micrometers) of A beta (IB) fibers?

a. 19 - 24
b. 12-20
c. 10-15
d. 5-15
e. 3-8
f. 1-3

Answer 11

c. 10-15

Question 12

______ are found in the germinal layer (stratum basale) of the epidermis. Axonal branches end as flattened expansions, each being closely applied to a Merkel cell.

Answer 12

Merkel endings

Question 13

What are general sensory endings?

Answer 13

They are biological transducers, in which physical or chemical stimuli create action potentials in nerve endings.

General sensory endings are scattered profusely throughout the body.

The resulting nerve impulses, on reaching the central nervous system (CNS), produce reflex responses, awareness of the stimuli, or both.

These structures respond to stimuli for pain, temperature, touch, and pressure.

Question 14

Which of the following sensory endings are superficially located, such as those in the skin.

a. Exteroceptors
b. Interoceptors
c. Proprioceptors

Answer 14

a. Exteroceptors

These structures respond to stimuli for pain, temperature, touch, and pressure.

Question 15

_____ are cage-like formations of axons that surround hair follicles. A single axon sends branches to many hair follicles, and each follicle is supplied by from 2 to 20 axons.

a. Cutaneous plexuses
b. Free nerve endings
c. Merkel endings
d. Peritrichial nerve endings

Answer 15

d. Peritrichial nerve endings

Question 16

What is the external diameter (micrometers) of B fibers?

a. 19 - 24
b. 12-20
c. 10-15
d. 5-15
e. 3-8
f. 1-3

Answer 16

f. 1-3

Question 17

List the four encapsulated sensory endings.

Answer 17

A. The Ruffini ending
B. The Pacinian corpuscle (or Vater-Pacini corpuscle)
C. Meissner’s tactile corpuscles
D. End bulbs

Question 18

What do proprioceptors provide data for?

Answer 18

Proprioceptors provide data or information for reflex adjustments of
muscle action and for awareness of position and movement.

Question 19

The _______ lies in the loose connective tissue deep to the skin

Answer 19

subcutaneous plexus

Question 20

Where are Ruffini endings found?

Answer 20

Ruffini endings are present in the subcutaneous tissue and dermis of both hairy and glabrous skin.

Question 21

________ consists of a single axon that loses its myelin sheath and is encapsulated by several layers of flattened cells with greatly attenuated cytoplasm.

A. The Ruffini ending
B. The Pacinian corpuscle (or Vater-Pacini corpuscle)
C. Meissner’s tactile corpuscles
D. End bulbs

Answer 21

B. The Pacinian corpuscle (or Vater-Pacini corpuscle)

Question 22

Which of the following are NOT present in the subcutaneous
tissue and dermis of both hairy and glabrous skin.

A. The Ruffini ending
B. The Pacinian corpuscle (or Vater-Pacini corpuscle)
C. Meissner’s tactile corpuscles

Answer 22

C. Meissner’s tactile corpuscles

Question 23

What is the conduction velocity of B fibers (m/sec)?

a. 15-40
b. 5-15
c. 0.5-2.5
d. 10-30
e. 70-120

Answer 23

b. 5-15

Question 24

The _______ lies in the papillary layer of the dermis, immediately beneath the epidermis.

Answer 24

papillary plexus