Nervous System

Question 1

What are the 2 divisions of the nervous system?

Answer 1

central nervous system and peripheral nerves system

Question 2

What are the 2 divisions of the PNS?

Answer 2

sensory/afferent division and motor/efferent division

Question 3

Describe the sensory/afferent division of the PNS

Answer 3

has sensory receptors that detect stimuli (change in internal or external environments)

Question 4

Describe the motor/efferent division of the PNS

Answer 4

• nerves convey impulses away from CNS
• innervates (supplies nerves to) effectors = muscles + glands (endocrine or exocrine)

Question 5

What are the cell types of the nervous system?

Answer 5

• neurons
• neuroglia

Question 6

What do neurons do? Where are they located?

Answer 6

• they conduct impulses
• make up the CNS and PNS
• mostly amitotic (irreplaceable)
  - exceptions for taste, olfaction, and memory

Question 7

Describe the cell body structure of a neuron

Answer 7

• has typical organelles
• RER called Nissl Bodies
• group//clusters in CNS = nuclei (grey matter)
• groups/clusters in PNS = ganglia

Question 8

What are the 2 processes from a neurons cell body called?

Answer 8

dendrites and axons

Question 9

What do dendrites of a neuron do?

Answer 9

they receive incoming messages + relay to cell body

Question 10

What are the parts of an axon in a neuron? What do they do?

Answer 10

• overall, carry impulses away from cell body
• axon hillock: where axon meets cell body
• axon terminal: typically branched with synaptic end bulbs (enlarged tips)

Question 11

Axon terminals may be:

Answer 11

1) myelinated: wrapped in many layers of cell membrane from Schwann cells (PNS) or oligodendrocytes (CNS)
2) unmyelinated: no myelin

Question 12

Describe myelinated axons

Answer 12

• electrical insulation
• gaps in myelin sheath are called Nodes of Ranvier
• myelinated axon bundles in:
  - CNS = tracts (white matter)
  - PNS = nerves

Question 13

What do neuroglia (glial cells) do?

Answer 13

support neuron cells = can undergo mitosis (prone to cancer specifically brain tumour)

Question 14

What are the 2 types of glial cells?

Answer 14

CNS neuroglia and PNS neuroglia

Question 15

What are the 4 types of CNS neuroglia?

Answer 15

• oligodendrocytes
• microglia
• astrocytes
• ependymal - neural epithelia

Question 16

What do oligodendrocytes produce? What are they a subtype of?

Answer 16

they produce myelin around axons and are a subtype of CNS neuroglia

Question 17

What do microglia do? What are they a subtype of?

Answer 17

they are protective, they become phagocytic if detect infected, dead, or damaged neurons (because immune cells can’t enter CNS)
- they are a subtype of CNS neuroglia

Question 18

What do astrocytes do? Where are they located? What are they a subtype of?

Answer 18

• they surround blood capillaries to form part of blood brain barrier (BBB)
• they help control capillary permeability
• they are a subtype of CNS neuroglia

Question 19

What do ependymal (neural epithelia) do? Where are they located? What are they a subtype of?

Answer 19

• they line brain ventricles and central canal of the spinal cord
• they secrete cerebrospinal fluid (CSF) and circulate it by cilia
• they are a subtype of CNS neuroglia

Question 20

What are the 2 subtypes of PNS neuroglia?

Answer 20

• shwann cells
• satellite cells

Question 21

Where are shwann cells do? What are they a subtype of?

Answer 21

• they form myelin around axons in PNS
• they are a subtype of PNS neuroglia

Question 22

Where are satellite cells located? What are they a subtype of?

Answer 22

• they surround neuron cell bodies in ganglia for protection and support?
• they are a subtype of PNS neuroglia

Question 23

What is structural/anatomical neuron classification based on?

Answer 23

based on # of cell processes off of cell body

Question 24

Describe unipolar neurons

Answer 24

• has 1 process that divides into two: central and peripheral
• peripheral end has dendrites (sensory receptors for pain, touch, etc) remainder is axon
• always sensory

Question 25

Describe bipolar neurons

Answer 25

• has 2 processes: 1 axon, 1 process with dendrites
• sensory: retina, nose (olfaction)

Question 26

Describe multipolar neurons

Answer 26

• has 3 or more: 1 axon, many dendrites
• all interneurons and motor neurons

Question 27

What are the functional types of neuron classification? What is it based on?

Answer 27

based on direction of impulse conduction
a) sensory/afferent
b) interneurons
c) efferent/motor

Question 28

Describe sensory/afferent neurons

Answer 28

• mostly unipolar
• from sensory receptors to CNS

Question 29

Describe interneurons

Answer 29

• within CNS (between sensory and motor)
• 99% of neurons (mostly multipolar)

Question 30

Describe efferent/motor neurons

Answer 30

• CNS to effectors (all multipolar)

Question 31

What are the 3 neuron junctions?

Answer 31

1) neuronal junction
2) neuromuscular junction
3) neuroglandular junction

Question 32

Describe neuronal junctions

Answer 32

• neuron to neuron
• can be chemical (use neurotransmitters) or electrical (ions)

Question 33

Describe neuromuscular junctions

Answer 33

• motor neuron to skeletal muscle

Question 34

Describe neuroglandular junctions

Answer 34

• motor neuron to gland

Question 35

What are they 4 most common chemical neuron synapses?

Answer 35

1) presynaptic neuron
2) axon terminal
3) synaptic cleft
4) postsynaptic neuron

Question 36

What are presynaptic neurons?

Answer 36

• a type of chemical neuron synapses
• they bring impulse

Question 37

What are axon terminals?

Answer 37

• a type of chemical neuron synapses
• have synaptic end bulbs: inside the bulbs (presynaptic membrane) are synaptic vesicles containing neurotransmitters

Question 38

What are synaptic clefts?

Answer 38

• a type of chemical neuron synapses
• space between neurons