Brainscape's Knowledge GenomeTM

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


See full index

CNS > Neurons & Glia > Flashcards

Neurons & Glia Flashcards

1
Q

Structure of neurons

A

Unipolar => 1 main projection from it

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

How many neurons are in the cerebrum

A

1011 neurons

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

In 99% of cases how do neurons receive info

A

Through their dendrites

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

How do neurons function

A

Using bioelectricity (like muscle cells)

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

Nerve and muscle cells are ________ __________

A

electrically excitable

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

Transmembrane potential

A

voltage difference across a cell membrane

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

resting membrane potential

A
  • -60 -> -80 mV
  • Unequal distribution of ions (Na+, K+, Cl-) across cell membrane
  • Greater permeability to K+ than Na+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the Na+/K+ electrogenic pump

A

Pumps 3 Na+ out and 2 K+ in

hence inside is made negative relative to outside

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

Distribution of ions within the cell and outside of it

A

Lots of K+ inside

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

EC and IC concentrations of:

  1. Na+
  2. Cl-
  3. K+
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What also pushes against the movement of K+

A

K+ is a +ve ion and outside is more positively charged than inside => more difficult for K+ to move due to electrical gradient

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

equilibrium potential for K+

A

When concentration gradient for K+ = electrical gradient pulling K+ in, the result is the equilibrium potential for K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Nernst equation

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

Equilibrium potential for:

  1. Cl-
  2. K+
  3. Na+
A
  1. -70 mV
  2. -80 mV
  3. +50 mV (cell membrane is relatively impermeable to Na+ when the cell is at rest
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many protein subunits compose an ion channel

A

4/5 subunits

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

how do mechanosensitive ion channels open

A

Sense sound - prise channel open - something PHYSICAL makes the ion channel open

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do ligand gated ion channels work

A

Shape of pore is altered by the binding of ligand to receptor on the surface of the channel

e.g. Na+ receptor binds ACh (nicotinic colinergic receptor) - binding site for ACh - Na+ passes through - when it binds to its receptor on the surface it changes the shape of the protein subunit and changes the lumen shape or size it becomes wide enough to allow Na+ to get through

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

How do VG ion channels work

A

The cause of the change in shape of protein subunit is the change in MP (ie change in proportion of +ve and -ve charges across the membrane) in vicinity of protein subunits

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

Action potential graph

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

4 principles that define an AP

A
  1. Threshold
  2. All or nothing
  3. Self-propagating
  4. Refractory period

* After an AP has occured there will be a period of time during which a) an AP cannot happen b) it would be very difficult for an AP to happen

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

Explain threshold and its relation to an AP being ‘all or nothing’

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

What does it mean when the MP is hyperpolarised

A

It is less likely that the neuron will become activated

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

Name an inhibitory NT

A

GABA

  • many anti-epileptic (abnormal electrical discharge within neurons) medicine mimics GABA
    • Hyperpolarises cell
    • Moves MP away from threshold
    • Reduces likelihood that the neurons are electrically active
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Name an excitatory NT

A

Glutamate (most common)

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

What channels are responsible for depolarisation

A

VG Na+ channels

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

threshold in relation to eq potential for Na+

A

+ 15 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Absolute vs relative refractory period

A
  • ABSOLUTE - impossible to reactivate that neuron
  • RELATIVE - physiologically very difficult to reactivate the neuron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Quantify the increase in conductance of Na+ at AP

A

x5000 increase in Na+ conductance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What channels are responsible for repolarisation

A

VG K+ channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Explain the refractory period of an AP

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What happens at threshold

A

VG Na+ channels are opened

15 mV more +ve than the RMP in neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

When does the inward flow of Na+ stop & how

A

When MP reaches the positive values

Related to a voltage sensitive change in the shape of the ion channels

=> inactivation of the VG Na+ channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

When MP is raised, what remedies the situation

A

The Na+/K+ ATPase

  • when the MP gets up to +ve values there will also be activation of the VG K+ channels which can then facilitate the repolarisation event
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How are APs self-propagating

A

Due to local circuits

  • Na+ influx depolarises the cell for up to 3mm along the axon
  • Adjacent areas reach threshold
  • Propagation of AP
  • Refractory period facilitates AP propagation in 1 direction only
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Where do APs usually happen

A

Within the axon hillock (cell body/dendrite area)

It then propagates down the axon in 1 direction due to refractory period

36
Q

What do you find in the dendrite region

A

Ligand sensitive channels, where the stimulus will occur

37
Q

What cells produce myelin

A

Glial cells

38
Q

Name the glial cells found in the PNS

A

Schwann cells

39
Q

Name the glial cells found in the CNS

A

Oligodendrocytes

40
Q

What is contained in the layers that the glial cells create

What does myelin do to ion channels

A

Sphingomyelin (lipid rich)

Creates a distance between active ion channels

41
Q

What is the size of glial cells

A

3mm in diameter

42
Q

Where are nodes of ranvier found

A

In between glial cells - ion channels are voltage sensitive

43
Q

What part of the brain makes us consciously aware of things

A

Only when it reaches our cerebral cortex, outer mantel of cerebrum

44
Q

Impact of diameter on nerve conduction

A

Wider the diameter, the greater the conduction

45
Q

General classification of nerves

A
  1. A (α, β, γ, δ) - largest // I
  2. B // I
  3. C (smallest) // II, III, IV
46
Q

What is activated the AP is propagated to the axon terminal

A

VG Ca2+ channels

47
Q

What does Ca2+ (greater conc outside, enters through ion channel) release activate

A

Ca2+ activates Ca2+-calmodulin dependent protein kinase II

48
Q

What does CAM kinase II do

A

Primes vesicles for mobilisation, docking to release sites on presynaptic membrane asnd membrane fusion

Precipitates exocytosis

49
Q

Name the scaffolding within the axon terminal

What does it do

A

Cytoskeleton (network of tubules and filaments) gives structure

It anchors NTs (vesicles) in the nerve terminal region for control

50
Q

What substance holds vesicles in place, as well as cytoskeleton

A

Synapsin

51
Q

What does Ca2+ phosphorylate

A

Synapsin to then release vesicle to docking site and hence release of NT

52
Q

What is a vesicle

A

A bubble of liquid bilayer

53
Q

What happens to NT left in the synaptic cleft

A

Vesicles reformed and NT taken back in

54
Q

explain synaptic transmission

A

There are receptors on the post-synaptic surface

Interactions of NTs with the receptors precipitates changes in the next cell

55
Q

How do you characterise most synaptic transmission

A

Axodendritic

56
Q

how do you characterise a small amount of transmission

A

Axosomatic => binding sites are on the cell body

57
Q

Describe ionotropic receptors

A
  • Protein subunits arranged around a pore
  • Fast activation
  • Short duration of action
  • ligand gated
58
Q

Describe metabotropic receptors

A
  • G-protein linked (inside surface)
  • Slow activation
  • Long duration of action
  • 7 transmembrane regions
  • NT dissociates from surface of the receptor
59
Q

Example of ionotropic receptor

A

Nicotinic

60
Q

Example of metabotropic receptor

A

Muscarinic

61
Q

What sort of effect does ACh have

A

Short sharp effect & can also have prolonged effect - subject to modulation by drugs

62
Q

What receptors does glutamate (most common excitatory NT in the brain) have

A

Ionotropic and metabotropic

63
Q

G protein coupled receptors

A
64
Q

What do excitatory NTs produce

A

Depolarisation of the postsynaptic membrane

65
Q

Is an EPSP an AP

A

It may favour an AP but it is not in itself one

  • no propagation
  • Graded responses obtainable
66
Q

What do inhibitory NTs produce

A

Hyperpolarisation of the post synaptic membrane

Makes it more difficult to trigger an AP

67
Q

Where is an AP often triggered

A

Axon hillock

68
Q

What is the role of summation

A

Key in occurence of AP

69
Q

What is spatial summation

A

Simultaneous activation of several dendrites because of the NT that’s released => AP triggered

70
Q

What is temporal summation

A

Zapped before it’s back to rest fully so it builds from there

Repetitive firing of a neuron can also result in threshold being reached

71
Q

Define glia

A

Protectors and support cells of neurons

Heighten the functional capacity of neurons

72
Q

Name the 6 different types of glia

A
  1. Schwann cells
  2. Oligodendrocytes
  3. Astrocytes
  4. Ependymal cells
  5. Microglia
  6. Radial glia
73
Q

What are the most common of all the glial cells

A

Astrocytes are the most common

74
Q

What glia are found when we’re developing as babies

A

Radial glia - facilitate the proper development of the brain

75
Q

What myelin-producing cells are found in the PNS

A

Schwann cells

76
Q

What myelin-producing cells are found in the CNS

A

Oligodendrocytes

77
Q

What glia control the EC environment around neurons

A

Astrocytes

Ependymal cells

78
Q

What glia have an immune function

A

Microglia

79
Q

Proportion of glia vs neurons

A

10-50x more glia than neurons

80
Q

Where are microglia derived from

A

Macrophages outside of CNS

  • Phagocytes - activated by infection and injury
81
Q

Where are macroglia derived from

A

Neural stem cells

82
Q

What are the 7 functions of macroglia

A
  1. Structural support
  2. Insulate axons
  3. BBB (CSF is basically BBB)
  4. Promote efficient signalling between neurons (e.g. clear NT from synapses, such as glutamate - taken into astrocytes)
  5. Release growth factors to nourish neurons
  6. Guide migrating neurons and axon outgrowth
  7. Synaptogenesis
83
Q

Astrocytes actively control _____________

What cells perform a similar function

A

synaptogenesis

  • Regulate synapse number
  • Regulate synapse function
  • Regulate synapse stability

(schwann cells can perform similar functions)

84
Q

Explain how macroglia have a crucial role in the anatomical development of the brain

A

A macroglial cell in the vicinity releases chemicals that can interact with neuron in the region

This communication results in neuron growing towards glial cell

Determines where the axon of a neuron actually terminates

85
Q

What do MACROglia do in synaptogenesis

A
  • EC protein signals from astrocytes trigger synapse formation in CNS
  • Neurons migrate during development but synapse formation only occurs when astrocytes (or other macroglia) are present
    • Microglia cannot perform this function
    • adult hippocampal sten cells display similar dependence on astrocytes for synapse formation
    • Schwann cells in the periphery trigger neuromuscular junction formation
86
Q

What are macroglia also needed for

A

Synapse maintenance

87
Q

How do glia sense synaptic activity

What do they do in response

A

Through increasing IC Ca2+ levels (calcium transient currents)

  • Respond by releasing gliotransmitters
  • Release transmitters in response to neuronal activity

CNS (36 decks)

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