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Neuroscience and Mental health > 3. Cells of the nervous system > Flashcards

3. Cells of the nervous system Flashcards

1
Q

Neurone

A

Info. processing unit.
Responsible for generation and conduction of electrical signals
Communicate with one another via chemicals released at the synapse.
Supported by neuroglia

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2
Q

Cellular structure of all neurons is similar.

A 
Large nucleus 
Prominent nucleolus 
Abundant RER 
Well developed Golgi 
Abundant mitochondria 
Highly organised cytoskeleton
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3
Q

How is diversity is achieved by neurones?

A

differences in number and shape of their processes.

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4
Q

Why do neurones have abundant RER and Golgi?

A

For producing, processing and packaging proteins

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5
Q

Describe DENDRITES

A

Major area of reception of incoming information
Spread from cell body and branch frequently
Greatly increase SA
Can receive more inputs and from more locations

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6
Q

What are the protrusions coming out of dendrites called?

A

Dendritic spines

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7
Q

Describe the arrangement of primary, secondary and tertiary dendritic spines.

A

Primary dendritic spines come off the vertices of the pyramid
Secondary dendritic spines come off the primary
Tertiary dendritic spines come off the secondary

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8
Q

Why are dendritic spines described as ‘plastic’?

A

Can withdraw/ produce/ destroy spines

Excess alcohol, schizophrenia = destruction

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9
Q

What are dendritic spines full of? Why?

A

Many mitochondria

Indicates requirement for a lot of energy production

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10
Q

Describe AXONS

A

Conduct impulses away from cell body
Emerge at axon hillock
Usually 1 per cell
May branch after leaving cell body and at target
Prominent micro-tubules and neurofilaments

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11
Q

Size of axons vs dendrites

A

Axons are much smaller

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12
Q

How does the diameter axons and dendrites change as it moves further from the cell body?

A

Axon: Doesn’t: diameter is constant the whole distance so the conduction velocity remains the same the whole way
Dendrite: Diameter tapers

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13
Q

Why do Axons contain abundant intermediate filaments and microtubules:

A

IFs: Needs to maintain tensile strength over long distance, play critical role in determining axon calibre
Microtubules: To transport proteins, vesicles, mitochondria from cell body to synapse

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14
Q

What are the 3 domains of an axon? Describe them.

A

Node: No myelin, Site of Na+ channels
Paranode: next to node; site of tight junctions between the ends of the myelin sheath and the axon
Juxtaparanode: next to paranode, underneath the myelin sheath, site of K+ and Ca2+ channels

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15
Q

What are the 2 forms of axon terminal?

A

Butons

Varicosities

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16
Q

Where are varicosities found?

A

Along smooth muscle where 1 axon will stimulate the contraction of several smooth muscle cells (multiple swellings synapse onto different cells)

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17
Q

Describe a bouton

A

Swelling at the end of an axon, where synapse is present

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18
Q

What is responsible for synaptic density?

A

Increased number of proteins in that area responsible for the machinery of releasing vesicles

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19
Q

What happens to competing inputs? (excitatory and inhibitory)

A

Neuronal integration

Integrated in postsynaptic neurone to produce a single digital output

20
Q

What are the 3 types of synapse?

A

Axo-dendritic (often excitatory)= majority
Axo-somatic (often inhibitory)
Axo-axonic (often modulatory): modulate action already passing down axon

21
Q

What determines how fast an AP is transmitted?

A

Axon calibre

22
Q

What is a key feature of fast axonal transport of vesicles of neurotransmitter?

A

Vesicles of neurotransmitter are carried along microtubules
Microtubules are unidirectional because they are polarised.
Retrograde transport occurs along other unidirectional microtubules.

23
Q

What happens when the axon is damaged during multiple sclerosis? What is this comprised of?

A

Swelling due to compression of axon/ axon transected

Swelling= vesicular protein build up

24
Q

Name 4 morphological subtypes of neurones

A

Pseudounipolar: single axonal projection that divides into 2
Bipolar: 1 axon, 1 dendrite projection
Golgi type I multipolar
Golgi Type II multipolar

25
Q

Describe Golgi type I multipolar cells

A

Highly branched dendritic trees
Axons extend long distances
Most metabolically active
Most vulnerable to degeneration

26
Q

Describe Golgi type II multipolar cells

A

Highly branched dendritic trees
Short axons
Axons terminate quite close to cell body of origin
Main output neurones

27
Q

What is the difference between Golgi Type I cells and Golgi Type II cells?

A

Type I have long axons

Type II have short axons

28
Q

Functional classification of neurones

A

Sensory neurons: Take input into brain
Motor neurons: Main output to skeletal and smooth muscle
Interneurons: Links neurones: responsible for modification, coordination, integration, facilitation and inhibition of sensory input

29
Q

What are neuroglia?

A

All cell types in CNS that aren’t neurones

Support cells

30
Q

Name 7 neuroglia

A 
Astroglia
Ogliodendria
Schwann cells 
Microglia 
Ependymal cells
Immature progenitors
Satellite glia
31
Q

Describe astroglia

A

Multi-processed star shaped
Most abundant cell type in brain
Numerous IF bundles in cytoplasm of fibrous astroglia (GFAP)
Signal to one another via Gap junctions

32
Q

2 types of astroglia

A

Proteoplasmic (grey matter)

Fibrous (mainly in white matter between axon bundles)

33
Q

List 11 functions of astroglia

A 
Support cells of CNS
Formation of blood-brain barrier
Facultative macrophages
Homeostasis: soak up neurotransmitter
Scaffold of neuronal migration and axon growth
Transport substances from blood to neurones
Segregation of synapses
Synthesis of neurotrophic factors
Neuronal-glial signalling
K+ ion buffering 
Glial scar formation
34
Q

What forms the glia limitans?

A

Packed dense layer of astrocytes (layers of end feet)

Forms barrier between brain and CSF

35
Q

How are astrocytes involved in the removal of neurotransmitters, K+ and H2O?

A

End feet on blood vessels involved in transport of K+ and H2O
Processes close to synapse involved in removing neurotransmitter

36
Q

Astrocyte end feet are wrapped around…

A

Blood vessels or Neurones

37
Q

What are the 2 forms of ogliodendroglia?

A

Interfascicular

Perineuronal

38
Q

Describe ogliodendroglia

A 
Small spherical nuclei and small cell body 
Dense nucleus and cytoplasm
Few thin processes
Prominent ER and Golgi 
Metabolically highly active
39
Q

Functions of ogliodendroglia

A

Production and maintenance of myelin sheath in CNS
Each cell produces multiple sheaths (1-40)
Continually degrade protein to make new protein to maintain membrane

40
Q

What is myelin?

A

A lipid rich insulating membrane

Up to 50 lamellae

41
Q

Name 2 myelin disease states

A 
Multiple Sclerosis (MS) 
Adrenoleucodystrophy
42
Q

Describe microglia

A

Derived from bone marrow
Resident macrophage population of CNS
Involved in immune surveillance
Present antigens to invading immune cells
1st cells to react to infection/ damage/ change in microenvironment
Role in tissue modelling

43
Q

Describe schwaan cells

A 
Perform functions of astrocytes in PNS 
Myelin producing cells of the PNS 
Each Schwann cell produces only 1 myelin sheath 
Surround unmyelinated axons 
Promote axon regeneration
44
Q

Where are Golgi Type I and Golgi Type II cells found?

A

Golgi Type I: pyramidal cells of the cerebral cortex, purkinje cells of cerebellum, anterior horn cells of spinal cord, long axons
Golgi Type II: short axons, stellate cells of the cerebral cortex and cerebellum

45
Q

What is the normal morphology of sensory neurones?

A

Pseudounipolar
2 branches
1 to the CNS
1 to the sensory receptor

Neuroscience and Mental health (11 decks)

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