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BDS2 OCB > OCB03-2003 > Flashcards

OCB03-2003 Flashcards

1
Q

What are neurofilaments? Describe their structure.

A

Intermediate filaments found in neurons that maintain cell structure

Coiled coil of polypeptides

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2
Q

Where is the action potential generated?

A

Axon hillock

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3
Q

What are other terms used for a neuron cell body?

A

Soma or perikaryon

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4
Q

What makes up the axon?

A

Axon hillock

Axolemma

Axoplasm

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5
Q

What are Nissl bodies?

A

RER

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6
Q

What is a multipolar neuron? Give an example.

A

Multiple processes leaving cell body

Motor neurons in ventral horn

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7
Q

What is a bipolar neuron? Give an example.

A

Two processes leaving cell body, one with dendrites and the other with terminals

Bipolar neurons of retina

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8
Q

What is a unipolar neuron?

A

One axon extends from cell body with a dendritic tree in the middle of it

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9
Q

In what kinds of organisms are unipolar neurons common?

A

Insects

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10
Q

What is a pseudounipolar neuron? Give an example.

A

One branch leaves the cell body and splits into two

Primary somatosensory neurons in dorsal root ganglia

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11
Q

What cells myelinate axons in the periphery?

A

Schwann cells

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12
Q

What cells myelinate axons in the CNS?

A

Oligodendrocytes

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13
Q

What are the gaps of non-myelinated axon called?

A

Nodes of Ranvier

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14
Q

What factors will maximise the speed of action potential conduction?

A

Large diameter

Myelination

(Increased temperature)

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15
Q

Which conducts impulses fastest: Aδ or C fibres?

A

Aδ fibres

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16
Q

What is the difference in nomenclature for fibres which are sensory/motor and sensory only?

A

Sensory/motor = capital letters (and sometimes a following Greek letter)

Sensory = Roman numerals (and sometimes a following lowercase letter)

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17
Q

What is the fastest sensory/motor nerve fibre type?

A

Aα fibres (eg α-motoneurons)

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18
Q

Are pain neurons myelinated?

A

Typically lightly or not myelinated

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19
Q

Is the nucleolus of a neuron prominent? Why?

A

Yes as neurons are transcriptionally and translationally active

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20
Q

What are the monomers of microtubules?

A

α and β tubulin

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21
Q

Which part of the cytoskeleton is associated with axonal transport?

A

Microtubules

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22
Q

In which direction does anterograde transport describe?

A

Towards plus ends (terminals)

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23
Q

In which direction does retrograde transport describe?

A

Towards minus ends (soma)

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24
Q

What molecular motor is used in anterograde transport?

A

Kinesins

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25
Q

What molecular motor is used in retrograde transport?

A

Dyneins

26
Q

Describe the polarity of microtubules.

A

Plus end = terminals

Minus end = soma

27
Q

How does kinesin move?

A

Two “heads” of the complex detach and reattach sequentially in an ATP-dependent manner

“Walking”

28
Q

How does dynein move?

A

ATP-dependent “sliding” movement

29
Q

Describe the properties of anterograde movement.

A

Fast via kinesins, 100-400mm/day to move mitochondria and vesicles to terminals

Slow via unknown mechanism, 0.5-10mm/day to move structural and metabolic elements

30
Q

Describe the properties of retrograde movement.

A

Fast via dyneins, 50-250mm/day to move aging mitochondria and vesicles

31
Q

What is the importance of retrograde transport?

A

Only way for soma to know if there is any damage to the nerve terminal (to change gene expression and start repair)

Also enables pathogens/viruses to spread easily along nerve pathways from the skin

32
Q

Which type of axonal transport is generally faster?

A

Anterograde

33
Q

What is Diffusion Tensor Imaging (DTI)?

A

Type of MRI

Allows visualisation of water movement in axons using “seed points” and “voxels”

34
Q

What is convergence?

A

Many presynaptic neurons ending on a single postsynaptic neuron

35
Q

What is divergence?

A

One presynaptic axon dividing into many branches to end on many postsynaptic neurons

36
Q

How many inputs does the average CNS neuron receive?

A

10,000

37
Q

How many inputs does a Purkinje cell of the cerebellum typically receive?

A

~300,000

38
Q

What is the significance of convergence and divergence in the CNS?

A

Many multiple ways of getting from one point to another in the brain

Each with their own neural consequences

Brain is like a super computer!

39
Q

What is the ratio of neuroglia to neurons?

A

10:1

40
Q

What are the two types of astrocytes?

A

Fibrous

Protoplasmic

41
Q

What are the functions of astrocytes?

A

Homeostatic:

  • regulate ionic environment (esp K+) and water
  • take up neurotransmitter (esp glutamate) and convert to glutamine
  • glycogen energy reserve for brain
  • regulate blood-brain barrier (glia limitans)

Structural:

  • bond axons together to give strength and stability
  • inhibit axon regeneration
  • myelination
42
Q

Which compound do astrocytes use to inhibit axon regeneration?

A

Chondroitin sulphate glycoprotein

43
Q

Which type of astrocyte clusters around synapses?

A

Protoplasmic

44
Q

Describe a protoplasmic astrocyte.

A

Greater number of shorter extensions

Largely confined to grey matter

45
Q

Describe a fibrous astrocyte.

A

Fewer number of longer extensions

Largely confined to white matter (for stability and support)

46
Q

How many axons can an oligodendrocyte myelinate?

A

Up to 40-50

47
Q

What functions do oligodendrocytes have?

A

Myelination

Inhibiting axon regeneration

48
Q

What is the function of the microglia?

A

Main cell responsible for removal of cellular debris and immune defence

49
Q

What prevents normal immune surveillance of the brain?

A

Blood-brain barrier

50
Q

How do microglia detect damage and react?

A

Normally have multiple processes expressing ATP receptors

ATP from damage or inflammation binds P2Y class of receptors causing a conformational change

Processes retract and the microglia becomes phagocytic

51
Q

What are the three types of ependymal cell?

A

Ependymocytes

Tanycytes

Choroid plexus cells

52
Q

Which type of ependymal cell is most abundant?

A

Ependymocytes

53
Q

What is the function of ependymocytes?

A

Form epithelial lining

Have cilia to circulate CSF and microvilli for absorption

54
Q

Describe a tanycyte and its function.

A

Elongated cell mainly associated with third ventricle

Acts as a sensor for secreted hormones (hypothalamus) and other small molecules in CSF

55
Q

Describe choroid plexus cells and their function.

A

Specialised cuboidal epithelial cells

CSF production in all ventricles of brain

56
Q

How many axons can a Schwann cell myelinate?

A

1

57
Q

What are the functions of Schwann cells?

A

Myelination

Promote axon regeneration

58
Q

How do Schwann cells promote axon regeneration?

A

Upregulation of permissive ECM components

Rapid removal of myelin debris by phagocytosis

59
Q

What is the function of satellite cells?

A

Structural support, homeostatic and metabolic support to neurons (similar role to astrocytes)

60
Q

What are satellite cells associated with?

A

Sensory neurons in dorsal root ganglia

Sympathetic ganglia

BDS2 OCB (22 decks)

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