Cells of the Nervous System 1 & 2

Question 1

neurons

Answer 1

are excitable cells
conduct impulses
integrate and relay info in a neural circuit

Question 2

glia

Answer 2

supporting cells, found around neurons
maintain homeostasis
protection
assist neural function

Question 3

Nissl (franz) staining

Answer 3

allows to distinguish between neurons and glia
nucleolus of all cells stained
neurons have Nissl bodies
- allows visulaisation of variation in size, density and distribution of neurons
if only nucleolus stained = glia
if area around nucleolus is stained too = neuron
highlight rRNA
dye binds to negatively charged things e.g. nucleotides

Question 4

The soma

Answer 4

nucleus
organelles for protein synthesis and processing: ribosomes, RER, Golgi
mitochondria = dense in neurons, movement of ions requires energy

Question 5

4 major components of neuron

Answer 5

1 - cell body, soma, perikaryon 
2 - dendrites
3 - axon
4 - presynaptic terminal
dendrites and axons = neurites = any process coming off a neuron

Question 6

Golgi (camillo) staining

Answer 6

silver chromate

small % stained - only highlights some neurons - randomly

Question 7

cytoskeleton (internal scaffolding)

Answer 7

microtubules - longitudinally down neurites, hollow tube made of polymers of tubulin
microfilaments - polymers of actin, longitudinally and membrane associated
both dynamically regulated - polymerisation and depolymerisation
neurofilaments = long protein molecules, wound together - very strong

Question 8

axon segments

Answer 8

axon hillock - wide part that attaches to soma
axon inital segment - specific ion channels, where action potentials are generated
axon collaterals - branches
axon terminal/terminal bouton

Question 9

features of axon

Answer 9

no RER or free ribosomes
different membrane composition
<1mm to >1m in length
1 micrometer to 25 micrometer in diameter - affects speed of conduction

Question 10

immunohistochemistry

Answer 10

specific primary antibodies bind to protein of choice, secondary one binds to primary and it fluoresces.

Question 11

presynaptic terminals

Answer 11

specialisation of terminal cytoplasm: no microtubules, synaptic vesicles, specialsed proteins or mitochondria
synaptic cleft
terminal arbour - lots of presynaptic terminals at end of axon
boutens en passent

Question 12

axoplasmic transport

Answer 12

moving things down axon, can be slow or fast
fast - radioactive amino acids, 1m a day, uses microtubules, kinesis and ATP
anterograde transport = moving down cell
retrograde transport = moving up cell, by dyenin

Question 13

manipulating axoplasmic transport

Answer 13

allows visualisation of cells

using antero/retrograde labelling, inject dye ino spinal cord - taken up by terminals and transported around body

Question 14

dendrites

Answer 14

branches form dendritic trees (arbours)
structure to function relationship - convergence = how many different synaptic inputs is one neuron dealing with
can have thousands of synapses
dendritic spines = increase surface area
plasticity - structure vs activity - can take in spines if not used
abnormalities = cognitive impairment

Question 15

staining methods

Answer 15

nissl stains
golgi stains
immunohistochemistry
live imaging of fluorescent dye - genetic or injected
electron microscope - synapses and organelles
retrograde tracers - HRP, find cell body location

Question 16

types neuron classification

Answer 16

1 - number of neurites
2 - dendritic geometry
3 - connections

Question 17

number of neurites classification

Answer 17

(axon or dendrites)
unipolar/pseudopolar
bipolar
multipolar

Question 18

unipolar / pseudopolar

Answer 18

splits in 2 e.g. dorsal root ganglion
peripheral process is part of axon too
small area for receiving synaptic input - highly specialised function
relay info reliably

Question 19

bipolar

Answer 19

e.g. retina - little integration, small area for recieving synaptic input
highly specialised for function
reliable relay of info

Question 20

multipolar

Answer 20

bigger tree = more integration
majority of neurons in brain
large area for reciving input
high levels of convergence

Question 21

dendritic geometry

Answer 21

pyramidal

stellate

Question 22

pyramidal geometry

Answer 22

distinct apical and basal dendritic trees, pyramidal shaped soma
common in cerebral cortex and hippocampus

Question 23

stellate geometry

Answer 23

star shaped dendritic arbour e.g. layers in neocortex

Question 24

connections in:

sensory

Answer 24

periphery —-> CNS

afferent

Question 25

connections in: | motor

Answer 25

ventral horn ----> peripheral | efferent

Question 26

interneuron connections

Answer 26

``` largest class, only in CNS relay or projection neurons - connect brain regions local interneurons - neighbouring cells - short axons - process info in local circuits ```

Question 27

nerve glue

Answer 27

glia fills space around neurons extracellular space of 20nm between glia and neurons can proliferate throughout life, neurons cant be replaced

Question 28

homeostatic myelinating phagocytic cells in: CNS

Answer 28

``` homeostatic = astrocytes myelinating = oligodendrites phagocytic = microglia ```

Question 29

homeostatic myelinating phagocytic cells in: PNS

Answer 29

``` homeostatic = satellite cells myelinating = Schwann cells phagocytic = schwann cells and macrophages ```

Question 30

homeostatic cells in: | ENS

Answer 30

enteric glia

Question 31

astrocytes

Answer 31

control environment surrounding neurons, have spacial domains contains unique marker - GFAP - glia fibrillary acidic protein, only expressed by astrocytes also - buffer extracell potassium and form part of blood brain barrier

Question 32

subtypes of astrocytes

Answer 32

``` fibrous protoplasmic radial glial cells - developmental muller cells - retina bergmann glia - cerebellum ependymal cells - line ventricles and central cord ```

Question 33

astrocytes as fuel suppliers

Answer 33

they supply fuel and add protection to brain glycogen stores of brain contain 5-10 mins supply metabolise glycogen and supply lactate endfeet take up glucose - help keep controlled environment

Question 34

tripartite synapse

Answer 34

terminates neuronal activity recycles neurot to presynaptic terminals, prevents over excitation asrocytes have receptors too

Question 35

microglia

Answer 35

macrophages of CNS, approx 15% of CNS glial cells neural development - growth factors, help neurons grow phagocytosis - apoptosis, clear debris oligodendrocyte myelination synaptic pruning however not always beneficial e.g. in neurodegenerative diseases

Question 36

oligodendrocytes

Answer 36

myelinating oligo form myelin sheaths of CNS axons insulate and change electrical activity can have 15-30 processes from cell body to myelin sheath

Question 37

schwann cells

Answer 37

form myelin sheaths of PNS | one schwann cell provides one myelin segment to a single axon

Question 38

myelin sheath

Answer 38

formation - process of oligodendrocyte cytoplasm wraps many times around axon cytoplasm squeezed out of layers by compaction maintain contact with glial cells for nourishment function - insulate and create nodes of ranvier enabling saltatory conduction