Cells of the Nervous System 1

Question 1

Neurones supported by?

Answer 1

Neuroglia

Question 2

Abundance of neuroglia compared with neurones?

Answer 2

9:1 neuroglia more abundant

Question 3

Neuronal components? (6)

Answer 3

Cell body
Dendrites
Axon
Axon terminals
Synapse
Neuronal cytoskeleton

Question 4

Neuronal cell body (soma) features?

Consider its high involvement in protein manufacture, packaging and secretion.

Answer 4

Large nucleus and prominent nucleolus
Abundant rough ER and free ribosomes
Well developed Golgi
Large number of mitochondria
Large number of lysosomes
Highly organised cytoskeleton

Question 5

Neuronal dendrite features?

Answer 5

Spread from soma
Branch frequently
Increase surface area of the neurone
Covered in protrusions called DENDRITIC SPINES

Question 6

Difference in diameter further away from cell body between axons and dendrites?

Answer 6

Dendrites = diameter decreases further away from cell body
Axons = diameter does not change no matter how far from cell body

Question 7

Neuronal axon features?

Answer 7

Emerge at axon hillock
Usually only one per cell but may branch extensively after leaving cell body/at target cell
Prominent microtubules and intermediate filaments (neurofilaments)
Can be myelinated or unmyelinated
Consists of 3 domains

Question 8

Function of dendrites?

Answer 8

Input - Major area of reception of incoming information to the cell body

Question 9

Function of axon?

Answer 9

Output - Conducts impulses away from the cell body

Question 10

Where are action potentials generated in the neurone?

Answer 10

Axon hillock

Question 11

Domains of the axon?

Answer 11

Node - consists of Na+ channels
Paranode - next to the node
Juxtaparanode - next to the paranode, consists of K+ channels

Question 12

What do axons form near their target?

Answer 12

Terminal branches

Synaptic terminals - Bouton/Varicosities

Question 13

Features and location of Bouton synaptic terminals?

Answer 13

Large, bulb-like structures at the end of the terminal branches (pre-synaptic knob)

Question 14

Features and location of varicosities (synaptic terminals)?

Answer 14

Swelling-like structures along the axon (multiple in an axon)
Form along smooth muscle so one axon can stimulate contraction of multiple smooth muscle cells

Question 15

How are synaptic vesicles packaged and transported?

Answer 15

Packaged in Golgi and transported by FAST ANTEROGRADE transport

Question 16

Synapse features?

Answer 16

Specialised mechanism for association of synaptic vesicles with plasma membrane (release of neurotransmitters)
Abundant mitochondria

Question 17

Neuronal cytoskeleton components?

Answer 17

Microfilaments
Intermediate filaments
Microtubules

Question 18

Neuronal cytoskeleton functions?

Answer 18

Maintain axon tensile strength

Transport of proteins

Question 19

Types of intracellular transport in neurones?

Answer 19

Fast axonal transport
Anterograde transport - both FAST and SLOW
Fast retrograde transport

Question 20

Fast axonal transport function, mechanism and speed?

Answer 20

Transport of MEMBRANE to different compartments
Vesicles with associated motors move along the axon
100-400mm per day

Question 21

Anterograde transport definition?

Answer 21

Transport of materials needed for neurotransmission and survival away from cell body

Question 22

Fast anterograde transport components, speed, and mechanism?

Answer 22

Synaptic vesicles, transmitters, mitochondria
400mm per day
Moves materials along microtubular network using specific molecular motors - requires ATP

Question 23

What is slow anterograde transport?

Answer 23

Cytoplasmic flow of soluble constituents away from cell body

Question 24

What is fast retrograde transport?

Answer 24

Return of organelles and transport of substances from extracellular space
Uses different molecular motors

Question 25

Anterograde moving vesicles and retrograde moving vesicles, same or different?

Answer 25

DIFFERENT - morphologically and biochemically different

Question 26

Morphological subtypes of neurones?

Answer 26

Pseudounipolar Bipolar Golgi type I multipolar Golgi type II multipolar

Question 27

Location, shape and function of pseudounipolar neurones?

Answer 27

Dorsal root ganglia sensory neurones Two fused axonal processes with a soma branching off Act as a continuous cable carrying action potentials from peripheral receptor organ to central terminal in spinal cord (sensory organ to spinal cord)

Question 28

Shape and location of bipolar neurones?

Answer 28

Two axonal processes extending from central soma | Found in cerebral cortex, retina

Question 29

Features of Golgi Type I multipolar neurones?

Answer 29

Highly branched dendritic trees Long axons Pyramidal cerebral cortex cells - output

Question 30

Features of Golgi Type II multipolar neurones?

Answer 30

Highly branched dendritic trees Short axons Excitatory input to cortical pyramidal cells

Question 31

Functional subtypes of neurones?

Answer 31

Sensory Motor Interneurones

Question 32

Features of sensory neurones?

Answer 32

Commonly pseudounipolar | Conducts impulses from sensory receptors to CNS

Question 33

Features of motor neurones?

Answer 33

Generally multipolar with large soma | Conduct impulses from CNS to effectors (muscles and glands)

Question 34

Features of interneurons?

Answer 34

Cell bodies and processes remain within CNS Make up majority of neurones within CNS Large multipolar or small bipolar

Question 35

Functions of interneurons?

Answer 35

Modification, coordination, integration facilitation and inhibition between sensory input and motor output

Question 36

CNS functional neurone groups?

Answer 36

``` Nucleus Laminae Ganglion Fibre tracts Nerves ```

Question 37

What is a nucleus group of neurones?

Answer 37

Group of UNENCAPSULATED neuronal cell bodies within CNS

Question 38

What are laminae?

Answer 38

Layers of neurones of similar type and function (cerebral cortex/cerebellar grey matter)

Question 39

What is a ganglion?

Answer 39

Group of ENCAPSULATED neuronal cell bodies in the peripheral nervous system

Question 40

What are fibre tracts?

Answer 40

Groups or bundles of axons in the CNS | Mixture of myelinated and unmyelinated

Question 41

What are nerves, functions?

Answer 41

Discrete bundles of axons Often mixed sensory and motor neurones Bring information to CNS from sensory receptors Bring axons from CNS to effector organs