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Neuro > Neurones And Neuroglia > Flashcards

Neurones And Neuroglia Flashcards

1
Q

what is the functional unit of the nervous system

A

neurons

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2
Q

Briefly describe neurons

A

excitable and can carry electrical signals. they are organised in circuits or networks that encode information for all conscious and non-conscious information in the CNS

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3
Q

what supports and protects the neurons

A

glial cells

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4
Q

ratio of glia to neurons?

A

10:1

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5
Q

Briefly describe glial cells

A

support and protect neurons. They have sorter processes. provide nervous system stem cell pool
provide a barrier between compartments. participate in neuronal activity. participate in metabolic assistance
provide the immune response to iflammation and injury to the NS

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6
Q

describe dentrites

A

short processes arising from the cell body
may contain dentritic spines
site of synaptic contacts

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7
Q

describe the cell body

A

houses the nucleus
site of protein, hormone and neurotransmitter production
gives rise to a single axon

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8
Q

other names for the cell body

A

perikaryon, soma

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9
Q

describe the axon

A

long, cylindrical and slender process, axon hillock and initial segment
axolemma (plasma membrane), axoplasm (cytoplasm)
myelinated or unmyelinated

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10
Q

describe the synapse

A

presynaptic terminal
synaptic cleft
post synaptic terminal

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11
Q

brief overview of metabolism and synthesis in neurons

A

cell body is the site of energy generation and synthesis
axonal transport - vesicles (fast axonal transport to terminal, retrograde to cell body)
electrical depolarisation

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12
Q

what is the resting membrane potential of neurons

A

-70mV

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13
Q

resting membrane potential of smooth muscle cell

A

-40mV

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14
Q

what is the resting membrane potential of cardiac cell

A

-90mV

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15
Q

How is the difference between the electrical charge inside the cell and outside the cell maintained

A

At rest K is higher than Na in the cell
Na leaks in
K leaks out
Na/K ATPase pumps out 3 Na in exchange for 2K pumped in

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16
Q

what leads to a change in membrane potential?

A

change in ion permeability

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17
Q

describe graded potentials

A

incoming signals and vary in strength
they lose strength over distance
slower than APs
Excitatory (EPSPs)
Inhibitory (IPSPs)

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18
Q

describe action potentials

A

travel very rapidly over longer distances

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19
Q

what are the 2 types of electrical signals

A

graded potentials and action potentials

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20
Q

net movement of ions does what to the cells

A

depolarises or hyperpolarises the cell

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21
Q

3 examples of gated ion channels

A

mechanically gated channels, voltage-gated, chemically gated

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22
Q

what happens when graded potentials travel to the trigger zone

A

subthreshold - too weak; no generation of AP
suprathreshold - generate AP

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23
Q

excitatory signal at trigger zone

A

depolarises, reduces threshold

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24
Q

inhibitory signal at trigger zone

A

hyperpolarises, increases threshold

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25
Q

describe the steps of an action potential

A

resting membrane potential, depolarising stimulus, membrane depol to threshold, colt gated Na channels open and Na enters the cell. Vol gated K channels open slowly; Rapid Na entry depol cell; Na channels close and slower K channels open; K moves from cell to extra cellular fluid; K channels remain open and K leaves cell, hyperpolarising; K close; cell returns to resting potential

26
Q

what are the 2 types of summation

A

temporal or spatial

27
Q

describe temporal summation

A

intense stimulation by ONE presynaptic neuron
EPSPs spread from ONE synapse to trigger zone
Post synaptic neuron fires

28
Q

Describe spatial summation

A

SImultaneous stimulation by several presynaptic neurons
EPSPs spread from several synapses to trigger zone
Postsynaptic neuron fires

29
Q

List 4 neuron types

A

pseudounipolar neurons
bipolar neurons
multipolar neurons
anaxonic neurons

30
Q

describe pseudounipolar neurons

A

found mainly in spinal ganglia
single process arises from the cell body and divides into 2 brances
one projects to the periphery and the other projects to the CNS. information collected from the terminals of the peripheral branch is transmitted to the CNS via the terminals of the other branch, bypasses the cell body
signals relayed from the receptor to the CNS without being modified

31
Q

describe bipolar neurons

A

have 2 processes - which arise from an elongated cell body
one process ends in dendrites, the other an axon
integrate multiple inputs and then pass that modified, processed information onto the next neuron in the chain

32
Q

where are bipolar neurons mainly found

A

in the retina and olfactory epithelium

33
Q

what is the most common type of neuron in the CNS

A

Multipolar

34
Q

describe multipolar neurons

A

possesses 3 or more dendrites which branch off directly from the cell body
have a single long axon issuing from the axon hillock

35
Q

describe anaxonic neurons

A

has only dendrites and no apparent axon can be determined

36
Q

what powers fast anterograde transport

A

Kinesin motors power anterograde transport (to synapse)
use ATP hydrolysis to walk toward plus-end. numerous kinesin-related proteins

37
Q

what powers fast retrograde transport

A

cytoplasmic dynein
uses ATP hydrolysis to walk minus end 50-200mm/day

38
Q

what exploits Cytoplasmic Dynein

A

viruses eg herpes simplex virus, rabies virus, polio

39
Q

what do the head of motors walk along

A

microtubules

40
Q

what determined cargo specificity

A

tail of motor protein

41
Q

what do neuroglia cells maintain

A

appropriate environment and provide structural support for normal neuronal functions

42
Q

what are the classification groups of neuroglia

A

astrocytes, oligodendrocytes, microglia, polydendrocytes, ependymal cells, satellite cells, schwann cells

43
Q

what is the tripartite synapse

A

Glutamate activates class1 metabotropic receptors; calcium release from astrocytes; resulting in release of gliotransmitters, modulate neuronal function; play a role in the regulation of local microcirculation in the brain

44
Q

describe astrocytes

A

largest glial cell, stellate appearance, centrally located nuclei; processes make contact with thousands of neurons, form end feet on blood vessels, shuttle excess ions, pick up glucose and metabolites from vasculature and carry them to neurons, major role in tripartite synapse

45
Q

what are the types of astrocytes

A

Fibrous (white matter)
Protoplasmic (grey matter)
Muller cells (retina)

46
Q

describe oligodendrocytes

A

myelinating cell within the CNS
smaller than astrocytes with fewer processes, can myelinate multiple axons

47
Q

describe microglia

A

smallest of all glial cells
derived from monocyte-macrophage lineage, immune cells of the CNS, activated by inflammatory markers, phagocytotic

48
Q

describe polydendrocytes

A

stem cell pool, recruited as oligodendrocyte precursors in remyelination, can provide link between neuronal signalling network and glial cells

49
Q

describe ependymal cells

A

epithelial cells that separate CSF from tissue

50
Q

describe satellite cells

A

similar to schwann
found in sensory, sympathetic, parasympathetic ganglia

51
Q

describe schwann cells

A

myelinating cells of the PNS, one schwann cell per axon. at neuromuscular junction can take up excessive neurotransmitter

52
Q

describe myelination in the PNS

A

axon comes into contact with the schwann cell which then rotates around the axon
as the schwann cell wraps around the axon, the cytoplasm becomes progressively reduced and the inner layers of the plasma membrane come into contact and fuse together

53
Q

describe myelination in the CNS

A

oligodendrocytes myelinate axons in the CNS. broad flat processes wrap about CNS axons, but the cell bodies do not surround the axons,
no neurolemma is formwed
little regrowth after injury is possible due to the lack of a distinct tube or neurolemma

54
Q

what is white matter

A

myelinated processes

55
Q

what is grey matter

A

nervel cell bodiues, dendrites, axon terminals, bundles of unmyelinated axons and neuroglia

56
Q

how does myelination in the CNS differ from the PNS

A

oligodendrocytes myelinate up to 50 axons each, not just 1
the myelin in oligodendrocytes has a different biochemical composition

57
Q

describe multiple sclerosis

A

autoimmune disorder causing disruption of myelin sheaths in CNS
sheaths becomes scars or plaquies, appears between ages 30 and 40. 2x more in women

58
Q

symptoms of MS

A

muscular weakness, abnormal sensations or double vision
remissions and relapses result in progressive, cumulative loss of function

59
Q

What is Guillan-Barre Syndrome

A

disease of the PNS involving an acute inflammatory, autoimmune attack on myelinated peripheral nerve fibres
potentially fatal neurological emergency and can lead to paralysis or death

60
Q

symptoms of Guillan-Barre Syndrome

A

weakness
loss of tendon reflexes
high spinal fluid protein without extra cells (albuminocytologic dissociation)

61
Q

what is Charcot-Marie-Tooth Disease

A

an inherited disorder of the PNS involving myelination

62
Q

signs and symptoms of CMT

A

pes cavus, distal wasting, weakness of intrinsic hand muscles, hypertrophy of the greater auricular nerve

Neuro (26 decks)

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