Brainscape's Knowledge GenomeTM

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


See full index

Neurology > Neurons and Glia > Flashcards

Neurons and Glia Flashcards

1
Q

What is contained within the nerve cell body?

A

Cell body contains the cell nucleus, the protein forming apparatus and endoplasmic reticulum etc.

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

What is the significance of dendrites on the nerve cell?

A

Dendrites grow out of the cell body-long thin extensions form the dendritic tree

These are the receptive surfaces of the nerve cell, and form a large enough SA for 100s of synaptic inputs

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

Describe the axon of the nerve cell

A

Axon is a single branching structure terminating in boutons (synaptic terminals)

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

Explain why nerve cells are so well perfused

A

Nerve cells are very metabolically active - have a large supply of capillaries

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

What brain section thickness is required to be seen under a microscope?

A

Need thin sections (typically 40-100μm for light microscopy of brain)
Nerve cells are seen through a hyper microscope

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

What main structure hinders the vew of brain details?

A

RBC are dark and will obscure details – they need to be removed

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

Explain how RBCs are removed from a brain section

A
  1. Remove blood (RBCs) by washing through with saline
    solution
  2. Add formaldehyde fix to form a solid sample
  3. Solid brain tissue formed - easier to cut
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 techniques used to slice a thin brain section?

A
  • Microtome (wax embedded)

- Cryostat (frozen)

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

Outline how a microtome is produced

A

In order to section the sample we can embed it in wax (holds it all together)
The wax segments stick together edge to edge so a whole strip can be lifted together in one piece ready for the microscope slide

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

Why may a cryostat be the preferred slicing technique over a microtome?

A

The wax can get in the way off many histochemical techniques

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

How do we overcome a pale and opaque brain section?

A

Sample is quite pale and opaque as the brain tissue is full of myelin and fats
Using a strong solvent render it transparent

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

Why do we need to stain the brain sample before viewing under a microscope?

A

Brain tissue no longer visible on microscope as transparent and featureless due to strong solvent

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

What are the different methods of making brain sections visible?

A
  1. Franz Nissl (late 19th Century)
  2. Camillo Golgi (late 19th Century)
  3. Intracellular injection of a label
  4. Small extracellular injections of tracer
  5. Electron microscopy
  6. Genetic manipulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does nissl staining work?

A 
Certain stains bind to the protein making apparatus in the nerve cell bodies - labels RNA
Darker areas (cerebral cortex) have more cell bodies
Paler areas (white matter) is where the nerve cell axons are running along
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the significance of Nissl staining?

A

Nissl staining enables us to see arrangement patterns within the cell bodies
Using this technique brogman (classical neuroscientist) was able to split the brain up into different functional areas

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

Outline how Camilo Golgi staining works

A

silver chromate could create a dense black stain, which labelled a small % of the cells present in their entirety - labels some cell bodies

Enables us to see not only the cell body but also the dendritic tree
We may also be able to see the beginning of the axons

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

What are multipolar neurons?

A

Many dendrites coming off the cell body

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

What is a stellate cell?

A

Different dendrites coming off cell body in all different directions evenly

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

What are pyramidal cells?

A

Triangular cell bodies, skirt of dendrites and an apical dendrite

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

What is meant by ‘spiny’ nerve cells?

A

Some cells are spiny others are non-spiny

Spines are the site of fast excitatory synaptic connections – inhibitory and modulatory synapses are found on the dendritic shafts in between, and the cell body itself.

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

What is the significance of spines?

A

Spines are plastic, changing in ways that strengthen or weaken the synaptic link, allowing neural circuits to embed new skills and memories.

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

Give an example of a pseudo-unipolar axon in the body

A

Pseudo-unipolar - axon from toe → brainstem

At the toe has an arborization with sensitive nerve endings

In the brain has arborizations with synaptic endings and the cell body is sitting in the dorsal root ganglion

This is a typical sensory neuron from the somatic sensory system

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

Evaluate the use of golgi staining

A

Golgi stain allowed classification but still unable to view much of the axon

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

What is the benefit of using an intracellular label injection?

A

Gives a more complete picture
Can visualise the tracer

The same histochemical techniques can highlight multiple features in the same tissue and can be combined with physiological measurements of the living cell

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

How does intracellular injection work?

A

Cells are labelled with a small, soluble molecule (eg biocytin) which is made
visible via a chemical reaction.

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

Explain how intracellular injection of a label is carried out

A

Done using a finely drawn pipette, starting off with a capillary glass. Can infuse the cell with a tracer if done accurately

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

What is biotin?

A

A vitamin that helps cells produce energy and boost nerve function in high doses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How is biotin visualised using intracellular label injection?

A

Expose the sections to antibodies with binding sites for biotin
More antibodies are raised against those antibodies

The latter can be linked to a fluorescent protein (visible under appropriate illumination)
OR
Horseradish peroxidase (HRP) an enzyme catalysing the conversion of the soluble molecule into a dark, dense insoluble

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

What is the purpose of small extracellular tracer injections?

A

Can see the dendritic pattern, shape and morphology

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

What structures take up the small intracellular tracer injection?

A

Taken up by cells and synaptic cells

Transported by axons and taken up by axon terminals - transported retrogradely to the cell body

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

Why is electron microscopy used to view brain sections?

A

Intracellular structure is invisible to light microscopy

32
Q

Outline the features of using an electron microscope

A

Uses a beam of electrons and a camera in place of light rays and the observer’s eye
Ultrathin sections, typically 30-60nm
Magnification >100,000x
Resolution to <0.5nm

33
Q

What is a neuropil?

A

A dense network of interwoven nerve fibres and their branches and synapses, together with glial filaments

34
Q

WHat is the appearance of neuropils under electron microscopy?

A

Thickened and smeared appearance at synapse (can see the vesicles containing the neurotransmitter)
External membranes seen as black lines

35
Q

Why are the membranes thicker at neuropils than elsewhere in the brain section?

A

Membranes are thicker than elsewhere on the profile as there is a big mass of protein in the presynaptic membrane which grabs hold of the vesicles

36
Q

Explain how the thickened membrane aids neurotransmitter release

A
  1. The protein structures pulls the vesicles against the
    membrane
  2. Action potential arrives at the membrane causing Ca2+
    to enter the terminal
  3. Ca2+ binds to some of the proteins
  4. The proteins pull the vesicles back into the membrane
    turning it inside out, becoming part of the external
    membrane
  5. Release of the neurotransmitter
37
Q

How big is a typical synaptic cleft?

A

Synaptic cleft is typically 0.01-0.02υm wide in nerve-nerve synapses

38
Q

What proteins are involved in postsynaptic neurotransmitter relase?

A

The presynaptic & SNARE proteins release the neurotransmitter when action terminal arrives

39
Q

Why is the postsynaptic membrane also thickened in appearance under an electron microscope?

A

Postsynaptic membrane is also thickened and smeared due to receptors, G proteins and enzymes activated by G proteins => convert neurotransmitter into action potential on to effector

40
Q

Where are excitatory and inhibitory synapses found on nerve cells?

A

Inhibitory / modulatory synapses are found on dendritic shafts and soma, excitatory ones on the spine heads.

41
Q

Wjy do synapses change shape and size?

A

Changes in the size, shape and number of spines are part of the mechanism that allows synapses to change strength, as happens during learning a new skill or laying down a new memory.

42
Q

How do thicker club head spines form?

A

In early development of dendritic spines put out long, thin filopodia that search for axons to connect with. Initially form a test connection; if it performs well the connection strengthens to form a club head shape to increase SA for a more powerful synapse

43
Q

Why does the axon appear dotted under electron microscopy?

A

The dotted look of the axon is due to the cut ends of the cytoskeleton

44
Q

Where in the nerve cells are microtubules found?

A

Microtubules run down the axon through the dendrites.

45
Q

What is the function of microtubules?

A

Provide the cell with strength and rigidity.

These are the motorways along which motor molecules travel carrying substances along the cell

46
Q

How are molecules carried along microtubules?

A

Substances moved retrogradely and anterogradely along axon length carrying structural proteins and neurotransmitter related proteins. Also carry signals released by the postsynaptic membrane.

47
Q

Outline the structure and function of microtubules

A

Relatively large (20nm diameter)
Run the length of neurites
Tubulin composition

48
Q

What molecules are carried along microtubules from the cell body?

A

Vital for transport of materials from the cell body eg:

  • structural proteins
  • neurotransmitter-associated proteins
  • organelles (eg mitochondria)
49
Q

What molecules re carried back to the cell body via microtubules?

A

And back towards the cell body:

  • signalling proteins
  • debris and used materials
50
Q

Outline the structure of actin filaments

A

Microfilaments

  • 5nm diameter ~the same as the neuronal membrane
  • Numerous in neurites
  • Actin composition
51
Q

What is the function of actin microfilaments?

A

Provide support, helping to maintain the shape of the cell body and neurites.

Play a vital role in neural embryonic growth, helping to shape axons and dendrites

Change the shape of dendritic spines and hence the strength of synapses, during memory formation.

52
Q

What is the role of actin in early development?

A

During early development actin guides the growth of axons and dendrites
Actin bundles produce long thin processes that stick out of growth cones of axons and dendrites, pointing in all directions, searching for guidance signals
Actin bundles will guide axon to grow towards the positive growth signals

53
Q

What are neurofilaments?

A

10nm - called intermediate filaments in other cell types

54
Q

What is the composition of neurofilaments?

A

Composed of 5 proteins:
NFL, NFM, NFH, internexin, peripherin
Protein combinations dependent upon neuronal cell type and development stage

55
Q

What is the Tau protein?

A

One of the proteins that bind together the cytoskeletal elements

56
Q

What are the effects of an abnormal Tau protein?

A

Abnormal Tau protein produces dense, intracellular tangles of cytoskeleton - seen in Alzheimer’s disease

57
Q

How is genetic manipulation used to visualise brain specimens?

A

Use viral vectors to insert jellyfish fluorescent protein genes into various species

58
Q

How are mice genetically manipulated to aid neuron and glia visualisation?

A

We can now engineer mice to express tracer protein genes only in specific cells

59
Q

What specific mice cells can be used to express tracer protein genes?

A

– cells using a specific neurotransmitter
– cells of a specific type
– cells that make a specific type of connection

60
Q

What is the benefit of using genetic manipulation to visualise brain sections?

A

Don’t have to inject in a label; cells produce their own

=> don’t have to cut the brain into sections

We can make brain transparent using a strong solvent
=> can produce a transparent brain with glowing GOIs in their exact location interacting normally (in situ)

61
Q

What are the 3 types of ‘real’ glia cells?

A

Astrocytes
Oligodendrocytes
Neurolemmocytes (Schwann cells)

62
Q

What categorises a cell as a glial cell?

A

4 different types of glial cells (one isn’t even classed as a glial cell)

3 actual glial cells were produced by the neural tube by the same stem cells producing nerve cells; later in development they switch into glial cells from nerve cells

63
Q

What is the role of astrocytes?

A

Astrocytes control the biochemical environment of nerve cells by regulating the movement of materials into / out of tissue.

64
Q

What is the significance of astrocytes?

A

Astrocytes are now seen as part of the neural circuit, capable of controlling nerve cell activity and hence information processing in the neural circuit

65
Q

What are the main functions of astrocytes?

A

Regulate contents of the extracellular space
Express receptors
Release neurotransmitter

66
Q

How do astrocytes control the biochemical brain environment?

A

Astrocytes regulate tight junctions forming blood brain barrier
Also pump csf which runs down capillaries –> neural tissue from the thin external meninges layer
- drive the flow of fluid into and through the neural tissue, flushing waste products from the brain (acts as lymphatics; occurs at night)

Astrocytes link together into “chain gangs” that transport material to / from neurones
Manufacture / break down substances on behalf of neurones - vital role in injury and repair
Form a blanket around nerve cells - pump Na/K in/out of own membranes to maintain correct [ICF] for correct function

67
Q

What is the purpose of myelinating glia?

A

Oligodendrocytes and Neurolemmocytes (Schwann cells) form the myelin sheath

Neurolemmocytes (Schwann cells) each myelinate a single axon in peripheral nerve

68
Q

How do Schwann cells myelinate the axon?

A

In both myelinating glial cells, the cell wraps its own extracellular membrane around the nerve cell producing layers of phospholipid membrane

Under the membrane, the nerve cell doesn’t introduce channel proteins into its own extracellular membrane - ensures insulation to prevent ion leakage

69
Q

Are unmyelinated axons unprotected from ion leakage?

A

some axons are unmyelinated, but are still protected by glial cells

70
Q

Where are oligodendrocytes found?

A

Oligodendrocytes myelinate multiple axons in the CNS (e.g. white matter of brain)

71
Q

How do oligodendrocytes differ from schwann cells?

A

Schwann cells produce a single length of myelin each

Oligodendrocytes produce many processes extending from its cell body, each one then produces a length of myelin

Oligodendrocytes act the same as Schwann cells but for multiple axons at once

72
Q

How do myelinating cells aid injury and repair?

A

Myelinating cells also secrete growth and inhibitory factors that control axon regeneration after injury.

73
Q

What is the consequence of non functional oligodendrocytes?

A

Degeneration of oligodendrocytes is associated with multiple sclerosis

74
Q

What are microglia?

A

Microglia are immune cells arising from the mesoderm (not neural tube) that migrate into the CNS very early in development

75
Q

What are the roles of microglia?

A
  • Help direct neurone development
  • Constantly monitor neurone health thereafter
  • Become amoeboid and travel to areas of injury /
    infection
  • Engulf and eliminate microbes, damaged cells and other
    particulate matter
  • Secrete essential recovery and repair factors

Neurology (20 decks)

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