BMS11004 WEEK 1 - WEDNESDAY, THURSDAY

Question 1

outline main role of neurons

Answer 1

excitable cells conducting impulses, to integrate and relay info within neural circuit

Question 2

outline main role of glial cells

Answer 2

supporting cells, surround neurons, glue, maintain homeostasis, protection, assist neural function

Question 3

explain what neural circuits are

Answer 3

join together to form neural systems
made up of neurons and glial cells

Question 4

what does nissel staining show

Answer 4

distinguish between neurons and glia, stains cell nucleuolus. darker circles are glial cell nucleolus, dark circles with surrounding purple are neurons
bind to negative charge (so bind to RNA) so only stain soma
neuron has nissl bodies allowing visualisation of variation in size, density and distribution

Question 5

name the 4 main compartments of a neuron

Answer 5

1. soma/perikaryon
2. dendrites
3. axon
4. presynaptic terminal

Question 6

what does golgi (camillo) stain do

Answer 6

small % silver chromate to show soma, processes
doesn’t show all neurons - unknown why
Cajal used this to map out parts of brains and neurons

Question 7

name 3 components of cytoskeleton

Answer 7

microtubules, microfilaments, neurofilaments

Question 8

what are microtubules

Answer 8

longitudinally down neurites, hollow tube composed of polymers of tubulin

Question 9

what is axon hillock

Answer 9

thick lump bit at top of axon

Question 10

what is role of axons initial segment

Answer 10

important specialised area in generation of AP

Question 11

what are axon collaterals

Answer 11

branches off main bit of axon (often at right angle), targets other neurons

Question 12

what do axons with “many levels” have

Answer 12

high levels of divergence of signals - wider spread of signals, instead of just relay between 2

Question 13

do axons have ribosomes

Answer 13

no rough ER (no ribosomes, no RNA so wont show on nissel stain)

Question 14

give the length and diameter of axons

Answer 14

length: <1mm to >1m
diameter: 1um-25um

Question 15

what is immunohistochemistry relating to axons

Answer 15

using antibodies (proteins specific to proteins) which may recognise sodium channel, then secondary antibody specific to primary antibody, with fluroescent secondary antibodies “tags”
very high v/gated Na+ channel density in axon initial segment as needed to activate AP

Question 16

give key features of presynaptic terminals

Answer 16

no microtubules, vesicles, many mitochondria, specialised receptor proteins on membrane, often branching to allow signal amplifications

Question 17

outline boutons en passent

Answer 17

“buttons in passing”, terminals placed along an axon

Question 18

what is axoplasmic transport

Answer 18

movement of material down axon, as cytoplasm of axon doesn’t have ribosomes so axon proteins need to be synthesised in soma and shipped down axon

Question 19

what is fast axoplasmic transport for and how far do they move

Answer 19

radioactive amino acids, 1000mm per day

Question 20

what is anterograde axoplasmic transport

Answer 20

move from soma to terminal
vesicles have proteins, eg: kinesin bound to them and use ATP to help them ‘walk’ microtubule down to temrinals

Question 21

what is retrograde axoplasmic transport

Answer 21

move from terminal to soma, eg: by dyenin
can be manipulated to study brain connection
inject tracer into muscle, taken up by presyn terminals and move back via dyein to soma. take samples and see where tracers are to find soma

Question 22

outline dendritic arbour

Answer 22

dendritic trees made from dendritic branches, allowing signal convergence (gathering signals from different axons and integrating to send to soma)

Question 23

give roles of dendritic spines, what happens with abnormalities or if not being used

Answer 23

isolate chemical reactions, plasticity, abnormalities can cause cognitive impairment, if less activity coming from synaptic terminal then dendritic spine lost

Question 24

name a nissl stain, and what it stains

Answer 24

cresyl violet
neurons, glia and cytoarchitecture

Question 25

what can electron microscopes study

Answer 25

synapses and organelles

Question 26

name 4 methods of structural neuronal classification

Answer 26

number of neurites dendritic geometry connection/projection axon length

Question 27

give 2 methods of classifying neurons by gene expression

Answer 27

underlying structural differences defines NT expression: inhibitory/excitatory

Question 28

neuronal classification: name 3 categories by neurites number

Answer 28

unipolar, bipolar, multipolar

Question 29

neuronal classification: explain unipolar

Answer 29

peripheral process is part axon too, small area for receiving inputs, reliable info relays includes pseudounipolar

Question 30

neuronal classification: what is pseudounipolar

Answer 30

eg: dorsal root ganglion, 1 neurite out of some that splits and has peripherally projecting and central projections. when sensing stimuli, peripheral sends info straight from peripheral to central

Question 31

neuronal classification: outline bipolar

Answer 31

one dendrite come off one side, axon off other. only has small dendritic area at end so less area for receiving synaptic input (but highly specialised function), reliable relay of info eg: retinal bipolar cells

Question 32

neuronal classification: outline multipolar

Answer 32

still only one axon can branch or have collaterals, but has dendrites coming off all sides of soma, with dendritic arbour receives around 150,000 contacts high level of convergence most of brains neurons eg: cerebellar purkinje cell

Question 33

dendritic geometry classifications- explain stellate cell

Answer 33

star shaped dendritic arbours

Question 34

dendritic geometry classifications- explain pyramidal cells

Answer 34

distinct atypical (long process coming off soma, splitting into tree) and basal (coming off around soma) dendritic trees pyramidial shaped soma allow integration of info

Question 35

explain what classification by neuron projections mean

Answer 35

classify neurons depending on whereabouts they project (sensory, motor, interneurons)

Question 36

neuronal projections classification- explain sensory

Answer 36

SNS- afferent carry sensory signal to CNS, efferent carry motor from CNS to skeletal muscle ANS- afferent carry sensory signal from internal organ to CNS, efferent carry motor from CNS to internal organ

Question 37

outline what sympathetic efferent nerves are, where do they project from/to

Answer 37

autonomic motor nerves, project from CNS in lumar and thoracic spinal cord region

Question 38

outline what parasympathetic efferent nerves are/do

Answer 38

autonomic motor nerve, project from brain and sacral region of spinal cord

Question 39

explain afferent+efferent

Answer 39

afferent = toward CNS efferent = away from CNS

Question 40

outline what interneurons are

Answer 40

largest class, dont leave CNS, integrate neural activity in brain structure, stay in structure alongside soma IN COMPARISON, to: relay/projection neurons connect brain regions, axons leaving soma area to go somewhere else in the nervous system

Question 41

explain knock-out gene-expression

Answer 41

manipulating neurons to genetically fluoress specific colour based on their gene expression use genetics for mapping projections eg: using GFP

Question 42

name 3 cell body shape classifications

Answer 42

ovoid fusiform triangular

Question 43

what are golgi type 1/2

Answer 43

golgi type 1 = long axon golgi type 2 = short axon

Question 44

what are glia

Answer 44

fills in space around neurons, can proliferate during life

Question 45

name glial cells involved in homeostasis, for CNS, PNS and ENS

Answer 45

CNS = astrocytes PNS = satellite cells ENS = enteric cells

Question 46

what is ENS

Answer 46

enteric nervous system, around gut

Question 47

what glial cells are myelinating cells in CNS and PNS

Answer 47

CNS = oligodendrocytes PNS = schwann cells

Question 48

what glial cells are phagocytic in CNS and PNS

Answer 48

CNS = microglia PNS = schwann cells and macrophages

Question 49

outline role of astrocytes

Answer 49

regulate chemical content of extracellular space (maintain ion level, pick up excess NT, actively remove NT via specialised proteins in membranes) buffer extracellular potassium forms BBB neurovascular coupling to change blood supply to neuron fence in neurons, cuff around NoR, ensheathe synapse and dendrite

Question 50

outline structure of astrocytes

Answer 50

tripartite synapse NT receptors which trigger electrical/biochem events within cell spatial domains unique GFAP markers for immunohisochemistry (allowing neurons to be identified, green tag)

Question 51

what is role of astrocytes in glycogen/glucose involvement

Answer 51

when not enough glucose an astrocyte act as glycogen store, breakdown glycogen to ATP for 5-10min supply needed for fuelling ion movement, walking kinesin along microtubule metabolise glycogen and supply lactate have processes surrounding blood vessels to take up glucose and convert to glycogen if needed

Question 52

explain role of microglia

Answer 52

macrophages of CNS, phagocytosis, tissue survelliance, when in inactive form can sense apoptois and become activated, then phagocytic allows BBB- immunologically privileged site

Question 53

outline structure of microglia

Answer 53

small rod shaped soma, with many extending symmetrical processes to search for infection

Question 54

what is a current research focus on microglia

Answer 54

potential harmful role for neurodegenerative disease, roles in cell death regulations

Question 55

outline function of oligodendrocytes

Answer 55

form CNS axon myelin sheath

Question 56

outline structure of oligodendrocytes

Answer 56

single sheet of ODC membranes wraps around 40-50 axon can have 15-30 priocesses extending from soma

Question 57

outline role of schwann cells

Answer 57

form PNS myelin sheath via oligo cytoplasms wrap multiple time around axon and cytoplasm being squeezed out of layers via compaction maintains contact with glial cells for nourishment guide axonal regeneration post damage (why only occur in PNS)