Microanatomy: Neural Tissue: The Peripheral Nervous System

Question 1

CNS arises from

Answer 1

Ectoderm

Question 2

PNS arises from

Answer 2

Neural crest

Question 3

Ectomesenchyme

Answer 3

o Neural crest-derived mesenchymal structures

Question 4

Neural crest contributes to formation of

Answer 4

o Cranial and spinal nerves
o Ganglia
o Motor and sensory nerve endings

Question 5

Types of neurons

Answer 5

• Multipolar
• Bipolar
• Unipolar

Question 6

Multipolar neurons have

Answer 6

• Numerous dendrites

- One axon

Question 7

Bipolar neurons have

Answer 7

2 processes: one dendrite, one axon

Question 8

Unipolar neurons have

Answer 8

One process: axon

Question 9

Afferent neurons

Answer 9

• Sensory

- Convey impulses from receptors into CNS

Question 10

Efferent neurons

Answer 10

• Motor

- Convey impulses from CNS to effector cells

Question 11

Interneuron

Answer 11

• Neurons which connect other neurons

- Majority of neurons are this type

Question 12

Neuroendocrine endings

Answer 12

Sites at which neurohormones are released into interstitial space/capillaries

Question 13

Schwann cells

Answer 13

Serve as support cells in PNS for myelination and for maintaining unique microenvironments for neural processes even for unmyelinated axons

Question 14

Function of myelin

Answer 14

• Insulates axons

- Increases the speed for the action potential in salutatory conduction

Question 15

Salutatory conduction

Answer 15

Increases speed of propagation of nerve impulses in myelinated axons from Node of Ranvier

Question 16

Anterograde transport

Answer 16

• Carries material from perikaryon towards periphery

Question 17

Retrograde transport

Answer 17

• Carries material from axon terminal and dendrites towards perikaryon
• Potential pathway by which some toxins and viruses enter the nervous system at nerve endings

Question 18

Slow axonal transport

Answer 18

• Only anterograde
• Moves tubulin molecules and subunit proteins for filaments
• Does not require ATP

Question 19

Fast axonal transport

Answer 19

• Bi-directionally moves membrane-limited organelles towards synapse via kinesin
• Travel by salutatory motion
• Via dynein
• Requires ATP

Question 20

Neural tissue must be maintained within

Answer 20

a unique microenvironment

Question 21

In PNS microenvironment is established by

Answer 21

blood-nerve barrier

Question 22

in CNS microenviornment is

Answer 22

CSF

Question 23

___ contribute to blood-nerve barrier and help maintain CSF-like interior

Answer 23

Tight junctions