Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

neur2006 > deck 1 > Flashcards

deck 1 Flashcards

1
Q

patch clamp methods

A

whole cell
inside out
outside out
cell attached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

dis/advantages of cell attached

A

measurement of ion channels in a specific region.
can change the voltage or add ligand. cell remains whole more physiological conditions inside the cell. each cell= 1 point on a dose response curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

dis/advantages of inside-out

A

inside= extracellular medium experimenter in control of the intracellular side of the membrane (bath). e.g cell activated by internal ligand. often forms a vesicle have to stop from forming vesicle through low ca2+ solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

dis/advantages of outside out

A

pippete= intracellular medium
can test the effect of external ligand.
often used for conc jumps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

dis/advantages of whole cell

A

cell membrane ruptured electrode sees all channels contribution to membrane potential etc. cell contents washed out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is charge measured in?

A

Charge (Q) measured in Coulombs (C)
1 mole of monovalent ion= Faraday’s constant
Faradays constant=avogadro’s number x charge on ion (charge of +/- 1 = 1.6x10-19C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is current measured in?

A

Currrent (I) is measured in Amps
1 Ampere =flow of 1 C of charge in 1 second
I=dQ/dT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Ohms law

A

V=IR

I=V/R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Conductance

A

Conductance is the reciprocal of resistance

G=1/R so I=VG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

summing up resistance

A

Series: add up resistance
Parallel: add up reciprocal of resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Capacitance

A

capacitance (C) in Farad (F)

1F= capacitance of an element that can store 1C of charge given 1V pd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you increase capacitance?

A
  • Increase plate area (larger diameter axon)
  • decrease interplate distance
  • better conducting material between the two plates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

summing up capacitance

A

in series: reciprocal adds up

in parallel: adds up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

properties of ion channels

A

voltage dependence
activation
inactivation
timing of activation in respect to each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

technical approaches to study ion channel

A

patch clamp
molecular cloning
crystallisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

main features of VGIC

A 
water filled pore
passive movement of ion down conc gradient
selectivity filter
gating properties to MP
inactivation->refractory period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

cause of selectivity filter

A

weak interaction between ion and charged AA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

gating current

A

very small current
1/1000 of a normal current
recorded after all ionic currents are removed
confirmational change moves the charged portion of the channel- causes current ( ithink)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Cloning of Nav channel

A

isolate mRNA including ones encoding Na+ channel and make cDNA library

aa sequence of small region of Nav channel purified
oligonucleotide probe with sequence corresponding to aa sequence.
hybridise to cDNA library containing Na+ channel cDNA
isolate and sequence Na+ channel cDNA. deduce protein sequence
aa sequence of entire Na+ channel

tested in oocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

hydorphobicity/philicity

A

ability of an aa to interact with water.

each aa has a specific value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how do you get DNA into eukaryotes

A

electroporation
ballistic method
DNA containing vesicle
calcium phosphatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what changes the magnitude of an AP

A

conc gradient
motility of ions ( depends on size and interactions with water
temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what forms the resting membrane potential

A

selective permeability
unequal distribution
ion exchange pumps
(maintained by Na+/k+ ATPase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Eion

A

membrane potential at which the concentration gradient is equal to the electrical gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

potential difference

A

work needed to move 1 unit of +ve charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

give the cellular equivalent of a battery

A

concentration gradient across an ion

27
Q

give the cellular equivalent of resistor/conductor

A

ion channel

28
Q

give the cellular equivalent of capacitor

A

ability of a membrane to store charge

29
Q

why does Vm decrease further from site of injection

A

more ion channels available- more leak

30
Q

effect of lambda (membrane length constant) on signalling

A

High Rm, high lamda, PSP can travel further along axon before being lost
low Rm low lambda, lots of ion leakage

increase diameter of axon, increase lambda, potential spreads faster- less to impede current flow

31
Q

lambda

A

effectively is the electrical conductivity of a neuron

32
Q

what is an action potential

A

transient reversal of the membrane potential that sweeps along the membrane of a neuron

33
Q

voltage clamp

A

xxxx

34
Q

how can you separate ion currents

A
  • modifying conc gradient of ion
  • substituting critical ion with impermeable ion of same charge so electrochemical gradient is not changed
  • selective ion blocker
35
Q

difference between Na+ and K+ conductance

A

Na+ channels open faster and inactivate faster

K+ channels open more slowly and stay open longer

36
Q

threshold potential

A

is the membrane voltage at which, enough Na+ channels are open to allow the overall flow of ions to be inwards

37
Q

Refractory period generated by?

A

inactivation of Na+ channels and increased K+ conductance

38
Q

AP propagation velocity depends on

A

axon diameter

passive membrane properties

39
Q

effect of Ra and Cm on velocity

A

rate of passive spread inversely proportional to RaCm
because:
-large Ra, smaller current so will take longer to depolarise the adjacent membrane
-lage Cm, takes longer to charge the membrane therefore longer to depolarise.

40
Q

how to speed up an AP

A

increase diameter of axon- reduces Ra as Ra=rax (pi x d^2/4)
C increases but linearly with radius.
Ra massively reduced Cm only slightly increased->RaCm decreased-speeds up AP

Myelination
C is inversely proportional to thicknes of membrane as capacitance increseases if conductors are closer together. saltatory conduction boosts the AP amplitude preventing it from dying out

41
Q

active transport

A

movement of substances against their concentration gradient.

42
Q

power sources for active transport

A

ATP hydrolysis

ion gradients

43
Q

function of AT

A 
establish electrochemical gradients
pH regulation
solute accumulation
termination of synaptic transmission
2nd messenger regulation
44
Q

an example of adhesion junctions

A

Cadherins
mechanical joining of cells
open lattice- allows fluid to penetrate deeper cell layers

45
Q

Impermeable junctions

A

tight junction in vertebrates
prevents molecules and transporters on one side of cell from moving to the other
allows specific functionality of different sides

46
Q

example of tight junctions

A

sealing of extracellular space in gut epithelium
active transporter on one side absorbs glucose
passive transporter on other side transport it to extracellular space so that glucose can not be lost back into the lumen of the gut

47
Q

what are gap junctions made up of?

A

connexins- assemble into channels (either heteromeric or homomeric)
form half a channel- connexon

48
Q

what do gap junctions do?

A 
make cytoplasm continuous between cells
can move cells up to 1000 molecular weight: 
-RNA
-peptides
-nucleotides
-vitamins
-sugars
49
Q

where were they discovered

A

NMJ of cuttlefish
1958 Furshpon + potter
hyperpolarising current both from nerve terminal to muscle and muscle to nerve terminal

can demonstrate their existence using voltage clamp- as they form the potential of 2 cells come closer together
(loewenstein)
increasing size of dyes (pon et al 2007)
radioactive thymidine in healthy cell attatched to 1 mutant cell ko for thymadine kinase. radioactive thymidine found in both

50
Q

where are they utilised?

A

heart to spread transmission between myocytes.- facilitates cotractile wave.
causes delay between atria and ventricles

smooth muscle in gut + uterus

51
Q

function of glia

A

regulate excitability- regulates K+ and glu

signals to neurons

52
Q

how many specialised processes do astrocytes have?

A

1- endfoot wraps around blood vessels
brings glucose into brain removes excess k+
BBB

53
Q

what happens if glia do not remove excess K+

A

AP comes in K+ leaves cell
in a train of APs the extracellular K+ can rise by 10-20mM
this rise in K+ can cause change in membrane voltage- depolarisation- cell more excitable more likely to fire AP.

This can lead to epileptic discharge
waves of spreading depression

54
Q

how does a wave of depression spread

A

K+ released from firing cell. makes neighbouring cells more excitable, makes them fire. wave of excitation causes Nav inactivation- depression in the brain moves a few mm at a time migraine

55
Q

How do glia deal with high K+

A

take up K+ through channel- K+ taken up until there is no driving force
take up K+ through Na+/K+ exchanger

56
Q

how much can a 10mM change in extracellular K+ change RMP

A

around 60mV

57
Q

what is glial RMP

A

almost exactly Ek+ - not permeable to Na+

58
Q

how does pump work

A

pump usually at 50% level. pump rate increases with K+ increase ( sigmoidal curve)
K+ pumped into glia with water- glia swell

59
Q

Spatial buffering

A

if K+ rises on one side of the glial cell it will take it up and release some in other areas to maintain its own MP and to not raise K+ too much through out the cell.
K+ rise has to be all around the cell in order to depolarise the cell. depolarised cell will cause K+ release. may be relesed 100s of micrometers from where the rise is as glia are electrically connected by gap junctions form large networks
large amounts of K+ dumped by endfoot near the blood vessel and taken out of the brain

Proven by Newman 1984
K+ added externally at different area and extracellular measurements taken all round cell. largest change at endfoot- 90% of ion channels in end foot

60
Q

what NT do glia cells help remove

A

Glutamate taken up into glia and broken down into glutamine via glutamate synthase either enters kreb cycle or taken up into presynaptic neuron by glutamine transporter
if not taken up quickly by glia can be neurotoxic

61
Q

how does glutamate cause neurotoxicity

A

AMPA receptors activated, Ca2+ enters cell and activates Ca2+ dependent enzymes (phospholipases [breaks down membrane] and ribonucleases [breaks down genetic material])

AMPA- Na+ moves in depolarises cell, Cl- drawn in followed by water- cell swells and bursts
NMDA do not desensitise

62
Q

what is needed for uptake of glut?

A

3 Na+ for 1 glutamate

causes depolarisation

63
Q

how is blood flow increased to sites based on activity

A

Glia activated
astrocytes receive GABA B or mGlu stimulation->
Ca2+ rise-> PLA2 converts arachidonic acid into prostaglandin. released onto smooth muscle- causes relaxation through hyperpolarisation- increases blood flow

64
Q

what is calcium used as a second messenger to do

A 
NT release
membrane excitability
synaptic plasticity
change in gene expression
growth and differentiation
neuronal death

neur2006 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions