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eBMS1052 > Wk1-3 FOUNDATIONS > Flashcards

Wk1-3 FOUNDATIONS Flashcards

1
Q

ICF ECF concs

A 
ICF= inc K+
ECF= inc Ca2+ and Cl-
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2
Q

describe cytoskeleton of neurons

A 
microtubules= run down neurites,mediate IC transport
neurofilaments = structural support, regulate diameter
microfilaments= actin molecules, link tubules and membrane
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3
Q

what is a neurite

A

projection out of the soma e.g: dendrites and axons

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4
Q

larger diameter=

A

lower resistance, easier transmittance

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5
Q

what is the axon proper

A

axon strand,

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6
Q

2 types of axon travel=

A

fast axoplasmic transport

slow axoplasmic transport

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7
Q

fast axoplasmic transport

A 
proteins travelling down microtubule, 
active process, 
proteins synthesised in soma transported to synapse 
waste from synapse transported to soma, 
1m/day
use kinesin/dynein proteins
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8
Q

anterograde via kinesin protein

A

towards synapse

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9
Q

retrograde via dynein protein

A

towards soma

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10
Q

slow axoplasmic transport

A 
unclear mechanisms (stops and go?)
not simply passive diffusion as it requires energy,
0.1-10mm/day
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11
Q

structure of axon terminals

A

no microtubules
many internal vesicles containing neurotransmitters
protein dense membrane
lots of mitochondria

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12
Q

what is a synapse

A

special connection between 2 neurons

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13
Q

describe chemical synapse

A

electric signal travels down axon
vesicles released in pre-synaptic membrane
travels through synaptic cleft
binds to specialised proteins at post-synaptic membrane
converted to electrical signal

slower than electrical synapses

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14
Q

outline dendrites

A

come off soma
spines protrude off dendrites to receive axonal inputs
dendrite arbor (tree-like structure) affects function

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15
Q

classifications of neurons

A 
number of neurites (uni bi multi polar)
shape and dendrites
connections
axon length
types of neurotransmitters used
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16
Q

what a glia

A

glia support neural function and may be involved in information transmission, some produce myelin (myelinating glia)

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17
Q

what does myelin sheath do

A

prevents ion movements in ICF and ECF
increases axonal conduction velocity
insulator

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18
Q

outline astrocytes

A

most glia in brain fill spaces between neurons and vessels
influence neurone growth and regulate ECF, neurotransmitters, metabolism, blood brain barrier
ensheath smaller molecules

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19
Q

outline microglia

A

remove debris of dead cells
flight response inflammation in brain
specialised immune system in brain

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20
Q

outline ependymal cells

A

epithelium-like cells
line fluid filled vesicles
produce cerebrospinal fluid (CSF) and controls release between brain tissue and ventricles

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21
Q

a higher ratio in nernst/GHK equation =

A

higher charge imbalance = higher ionic equilbrium potential

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22
Q

if a membrane is permeable to only 1 ion, mpot will

A

move towards that ions equilibrium potential

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23
Q

what is an ions equilibrium potentials

A

the voltage that counteracts the conc gradient of an ion.

if mpot = equilibrium pot then no movement of ion

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24
Q

GHK calculates

A

mpot

if you know conc and permeability of all ions involved

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25
Q

outline sodium potassium pump mechanism

A

2 conformations = open to ICF or ECF
ICF conf = bonds ATP and 3Na.

ATP hydrolysed changing conformation

ECF conf = releases Na bonds to 2K

causes dephosphorylation and a second conf change

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26
Q

outline potassium channels

A

membrane is 40x more permeable to K than Na due to K leaky channels
2 pore domain channels help set resting mpot

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27
Q

outline depolarisation

A

threshold potential is crossed causing voltage gated Na channels to open. mpot moves towards Na potential.

28
Q

outline repolarisation

A

when the threshold potential is first reached K channels are told to open too but are slower than Na channels. Na channels close and then most of the K channels are open causing repolarisation

29
Q

outline hyperpolarisation

A

these delayed-rectifier k channels take longer to close causing the mpot to become more negative. after all these are closed the mpot restores with leaky channels. this is also known as the relative refractory period limitng further AP generation

30
Q

what is the absolute refractory period

A

where APs rarely occur

Nav channels remain inactive during hyperpolarisation

31
Q

inactivation of Nav channels stops

A

back propagation

32
Q

outline saltatory conduction

A

AP propagation from jumping to nodes of ranvier. This is where ion channels are concentrated. more frequent gaps & smaller amounts of myelin are more effective in preserving the signal.

33
Q

outline electrical synapses

A

form gap junction of non selective channels
direct electrical coupling between cytosol of 2 neurons
physically close
small and instant
bidirectional
2nd synapse has smaller voltage

34
Q

chemical synapse classification: axon location

A

axo dendritic : synapse attaches to dendrites of other neuron
axo somatic
axo axonic

35
Q

chemical synapse classification: microscopic structure

A

grays type 1: asymmetrical, round vesicles, excitatory

grays type 2: symmetrical, inhibitory, less electron dense

36
Q

chemical synapse classification: by size

A

number and size of 2 neuron synapses indicates strength and importance of signalling.
inc strength = inc mpot = inc active zones present

37
Q

chemical synapse classification: by neurotransmitter

A

amino acids
amines
peptides

38
Q

chemical synapse classification: by effector

A

special example: neurotransmuscular junction which specialises in connection from motor neurons to muscle fibres

39
Q

outline neurotransmitter synthesis

A

made in neuron it belongs to

  • amino acids available in neuron are packaged
  • GABA and amines require enzymes
  • peptides packed in granules in nucleus and transported
40
Q

outline neurotransmitter release

A

Cav channels in active zones open when AP reaches.
Ca floods axon terminals triggering neurotransmitter release.
Na Ca exchanger pulls 1 Ca out of terminal for 3 Na

41
Q

outline neurotransmitter binding

A

2 methods

ionotropic: ligand gated channel on post synaptic membrane specific to neurotransmitter
metabotropic: linked with ion channels. acts through a second messenger. broader, distributed effects

42
Q

outline responses to neurotransmitter

A

post synaptic potential (PSP) change in mpot due to neurotransmitter mediated opening

Excitatory PSP (EPSP) = depolarisation (Na influx)
Inhibitory PSP (IPSP) = hyperpolarisation (Cl channels open)
43
Q

explain IPSP

A

Cl channels open but due to mpot being the same as Cl potential, no ion movement. however any Na influx that occurs will then be counteracted.

44
Q

outline recycling neurotransmitters

A

diffusion away from synapse
reuptake in pre synaptic terminal
enzymatic destruction break down

45
Q

outline receptor response to stimuli

A

stimulus has effect on target receptors
receptors convert into a type of energy (likely chemical)
signal received by sensory neurons (afferent nerve fibres)
passed to a relay neuron in brain
signal reaches motor neuron (efferent fibres) out to the effector which performs response

46
Q

3 types of receptors

A

somatic: for physical, touch position etc

special : for sense, smell taste etc

visceral : internal organs

47
Q

somatic nervous system

A

part of motor division of PNS

controls skeletal muscle contractions

48
Q

autonomic nervous system

A

part of motor division of PNS

made up of sympathetic (fight/flight) and parasympathetic (rest/digest)

49
Q

directions of body

A

top dorsal
bottom ventral
front rostral
back caudal

slicing through brain as a scanner
horizontal transverse
vertical scanning forward coronal
vertical scanning side sagittal

50
Q

outline sensory/motor neurons in CNS

A

sensory neurons:
cell body = dorsal root ganglion
axons enter = dorsal root
synapses = dorsal horn

motor neurons:
cell body = ventral horn
axons exit = ventral root
synapses = muscle fibres

51
Q

brain stem

A

made up of the medulla, pons and midbrain

52
Q

cerebellum

A

role in motor control

53
Q

diencephalon

A

thalamus: relay station, controls flow of signals to cerebrum
hypothalamus: regulates metabolic processes
pituitary gland: homeostasis, hormones
pineal gland: endocrine organ modulates sleep

54
Q

cerebrum

A

cerebral cortex: outermost sheet of neural tissue, sensory perception, motor control

basal ganglia: 4 internal nuclei, form feedback circuits with cerebral cortex

limic system: disparate collection of nuclei. made of hippocampus and amygdala

55
Q

meninges

A

3 protective membranes departing CNS and bone

dura mater: outermost closest to skull, tough bag surrounding brain and spinal cord

arachnoid mater: appearance of spiderwebbed web, impermeable to fluid, no space between dura

pia mater: thin membrane, close to brain surface, separated from arachnoid by CSF, many blood vessels

56
Q

CSF

A

produced by choroid plexus

situated within ventricles (4 cavaties in core of brain)

57
Q

BBB

A

restricts entry of macromolecules into brain
shield brain from abnormal variations in ionic composition and toxic molecules
tight junctions
astrocytes regulate blood flow
separation of blood flow incase of an increase in pressure

58
Q

extracellular recordings

A

electrode positioned in EC space.
one or more neurons may be recorded
electrical changes due to EC ions detected
provide info about networks of neurons

59
Q

intracellular recordings

A

electrode in single neuron
ion filled micropipette electrodes
patch clamp recording which can vary to look at different manipulation of mpot.

60
Q

computed axial tomography (CT scan)

A

multiple x ray images of brain
stacked together to produce 3D brain model
only detects brain structure, not function

61
Q

magnetic resonance imaging (MRI)

A

the energy emitted from the spin of hydrogen atoms subjected to strong magnetic field

fMRI looks at function changes

62
Q

what is a BOLD repsonse

A

blood oxygen level dependent response.
detectors detect more in brain in places that have more blood flow. higher score of BOLD signal can help find relations of function in brain parts.

63
Q

electroencephalography

A

recorded localised change in electrical activity in the brain through the placement of electrodes on the head.

64
Q

transcranial stimulation (TMS)

A

localised excitation of brain tissue by a magnetic current.

helps find relations between parts of the brain and modulate peoples behaviour

65
Q

optogenetics

A

modulates activity by introducing light sensitive channels and an electrode into subject brain

66
Q

microstimulation

A

intracellular: injecting current into single cell will change mpot
extracellular: injecting current into ECF will depolarise 100s of neurons.

eBMS1052 (8 decks)

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