Membrane potential, action potentials and synaptic transmission and perception Flashcards

1
Q

what is a membrane potential

A

difference in charge between the extracellular fluid and intracellular fluid

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2
Q

What is the concentration of sodium inside and outside of the cell

A

out 150mmol

in 15mmol

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3
Q

What is the concentration of potassium ions inside and outside of the cell

A

out 5mmol

in 150mmol

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4
Q

What is the concentration of anions inside and outside of the cell

A

out 0

in 65mmol

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5
Q

what has higher permeability potassium or sodium ions

A

potassium

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6
Q

If the positive concentration gradient is directed outside the cell which way is the electrical gradient directed

A

inside the cell

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7
Q

what is the main cause for the resting potential.

A

K+ diffuse out of the cells which creates a positive charge outside the cell.

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8
Q

What is the formula to work out the membrane potential

A

E = 61 log conc out/ conc in

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9
Q

Na+ enter the cell from the outside(extracellular) which makes the potential more positive to overall charge. What is the potential differnence

A

-70mv

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10
Q

Quickly describe the process of an ap being generated- using the graph with certain channels opening etc

what is threshold potential to

A

At resting potential , stimulus cause NA to open and reach threshold of -55 positive feedback causes voltage. gated sodium channels to open from threshold to to peak.
Pd now at +30mv , Na volatge gated close which is triggered at threshold but slow.
Efflux of K+ causes repolarisation. Potassium channels( I gate) open at threshold potential put slow. Pd overshoots causing hyperolarisation where potassium channels close.

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11
Q

What is the refractory period?

what molecules restore this

A

Ap ions are in the wrong place so restored by PAMPS

this makes sure the cell can recover and AP are only transmitted in one direction

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12
Q

What is GABA

A

GABA is an inhibitory neurotransmitter which binds to the GABA a receptor and causes hyperpolarisation of the post synaptic membrane due to causing an influx of K+
GABAb - potassium efflux
GABAa - influx of CL-

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13
Q

Temporal summation

A

2 or more AP I quick succession release enough neurotransmitter to trigger AP on next neuron

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14
Q

Spatical summation

A

pre neurones simultaneously coverage to release small amount of neurotransmitter - multi stimuli in 1 response

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15
Q

soma

A

body of the neurone

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16
Q

what does the axon do

A

carries impulses from the body

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17
Q

axon hillock

A

soma binds to the axon- where the theshold potential is met , all or nothing potential

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18
Q

intensity of AP

A

firing frequency

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19
Q

difference between neurone and a nerve

A

Neurone is one cell and a nerve is made up from multiple nerves.

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20
Q

Excitable cells – can generate an electrical current through ion channels what are the two types of excitable cells

A

muscle and nerve

21
Q

Neurofibrils are special features of neurones - what do they do?

A

provide cellular stability ad structure

  • Chains of tuberin running along axon to cell body and axon terminal
  • Moves vesicles along axon with foot like projections
22
Q

What are neurotubules?

A

microtubule transport system ,
chains of tubulin that run from the soma to the axon terminal
and have transport molecules on the chains that move vesicles along the outside of tubules -foot like process

23
Q

cell body —- axon terminal carries:

A

neurotransmitter vesicles, proteins and lipids on kinesis

24
Q

axon terminal —– cell body carries:

A

cell debris on dynein - energy dependent

25
wha does myelin provide and where does depolarisation take place
electrical insulation - and depolarisation takes place at the nodes of ranvier
26
what is saltatory conduction
ions only diffuse at gaps. local currents elongated speeding up transmission
27
Describe what a Schwann cell is where it is found
- In peripheral nervous system, Schwann cell wraps around one neurone.
28
describe what an oligodendrocyte is and where it is found
- In central nervous system, oligodendrocyte has multiple arms which wraps around multiple axons.
29
grey matter
cell bodies
30
white matter
axons
31
grey matter is found where in the brain
peripherally but central in the spinal cord
32
what are glial cells
non-neuronal cells in the CNS
33
4 types of glial cells
oligodendrocytes astrocytes microglia ependymal
34
what are astrocytes
maintain microstructure, blood brain barrier
35
what are microglia and what do they produce
immune cell ( monocyte) produce growth factors
36
what are ependymal cells
produce CSF , line CSf spaces, cilia aid CSF movement
37
3 connective tissues of nerves
endoneurium - connective tissue around myelin sheath of ash myelinated nerve fibre in PNS perineurium - surrounds bundle( fascicles) of nerve fibres within a nerve fascicles - bundle of axons , nerve fascicle - PNS in CNS this is known as a nerve tract epineurium - surrounds peripheral nerve -BV
38
3 main roles of peripheral nerves
motor, sensory and autonomic
39
efferent neurones
away from the CNS
40
afferent neurones
towards the CNS
41
what is fibre class based on
diameter and myelination
42
What are Adelta fibres function
fast pain and temperature towards the CNS
43
What are Abeta fibres function
afferent for touch and pressure
44
somatic sensory modalities (4)
tactile - pressure, touch and vibration pain proprioception - positions of limbs and static movement thermal
45
mechanoreceptors
deformation and stretching
46
thermoreceptors
temp
47
nociceptors
pain
48
What are the 2 types of nerve endings
free nerve endings - dendrites sit in tissue where single detected encapsulated nerve endings - deformed and enhances sensitivity - touch pressure and vibration