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Biological > 13) Nerve cells and nerve impulses > Flashcards

13) Nerve cells and nerve impulses Flashcards

1
Q

What is found in most multicellular animal species?

A

Nervous Tissue

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2
Q

Sponges don’t have Ns but have SJs

A

Neurons/Synaptic Junctions

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3
Q

Jellyfish nervous structure

A

diffuse net nerves, no CNS

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4
Q

Bilaterians nervous structure

A

Brain and nerve cord = CNS

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5
Q

Cephalisation

A

Nervous tissue concentrated toward one end of an organism

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6
Q

CNS

A

brain and spinal cord

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7
Q

PNS

A

Peripheral NS= nerves from sense organs to the CNS

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8
Q

Nervous system microstructure

A

Nerve cells (neurons)/ Glia cells

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9
Q

Cajal & Golgi (Nobel Prize)

A

found neurons are separable (small gap between the tips of one neurons fibres and the next neuron)
The NS consists of individual neurons

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10
Q

Neurons

A

nerve cells

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11
Q

how many neurons in cerebellum?

A

70 billion

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12
Q

how many neurons in cerebral cortex

A

12-15 billion

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13
Q

how many neurons in spinal cord

A

1 billion

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14
Q

glia cells

A

glial cells
neuroglia
smaller than neurons
more frequent (x1.2)

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15
Q

three most common glia cells

A

oligodendrocytes (76%)
astrocytes (17%)
microglia (6%)

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16
Q

glia cell functions (6)

A

1- provide structure - surround neurons and hold them in place
2 - insulate nerve cells with myelin sheaths
3 - supply nutrients and oxygen to neuron
4 - removal of dead neuronal tissue & immune defence of the CNS
5 - provide scaffolding for neurons to migrate to destination during development
6 - modulate neurotransmission in the synapses

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17
Q

astrocyte function

A

provide structure by surrounding neurons and holding them in place
supply nutrients and oxygen to neuron

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18
Q

oligodendrocytes

A

CNS

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19
Q

Schwann cells

A

PNS

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20
Q

phagocyte function

A

microglia - immune defence of the CNS

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21
Q

radial glia

A

provide scaffolding for neurons to migrate to destination during development

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22
Q

name three glial cell tumours

A

glioblastoma
astrocytoma
oligodendroglioma

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23
Q

neurons def

A

cells in the NS that specialise in performing information- processing tasks

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24
Q

neuron structure

A

body cell (soma) and fibres (dendrites and axon)

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25
Q

soma

A

cell body
contains nucleus and ‘machinery’

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26
Q

cell nucleus

A

contains genetic info of cell organized as DNA molecules

27
Q

cell ‘machinery’

A

mitochondria
ribosomes
endoplasmic reticulum
golgi apparatus
nissl bodies

28
Q

mitochondria

A

performs metabolic activities, extracts energy from nutrients

29
Q

ribosomes

A

protein production

30
Q

endoplasmic reticulum

A

transports proteins to other locations

31
Q

dendrites

A

branching fibres receiving information from other neurons
greater surface area, more info receivable

32
Q

where are synapses located on a dendrite

A

the surface - some have spines which enlarge the surface on which the synapses are placed

33
Q

axon

A

thin fibre - transmits information to other neurons - axon can be 1m long

34
Q

axon structure

A

distal part - branches
these swell at tip and form presynaptic terminal (end bulb or bouton)
some have boutons along the fibre - not just at the end

35
Q

bouton(s)

A

end bulbs (swollen sections) of axon fibres - can be along as well as on the end

36
Q

myelin sheath

A

insulating layer - speeds up electrical transmission

37
Q

why are neurons diverse shapes

A

specialisation

38
Q

three major types of neuron

A

afferent
efferent
interneurons

39
Q

afferent

A

sensory neurons - Afferent:Arrive
carry info from receptors

40
Q

efferent

A

Efferent:Exit
carry signals away to the effectors muscles or glands

41
Q

interneurons

A

connect other neurons

42
Q

neuronal activity

A

resting potential and neurons’ excitation

43
Q

Resting polarization

A

the membrane of a neuron maintains an electrical gradient (the difference in electrical charge) between the inside and the outside of the cell

44
Q

resting potential

A

the electrical potential inside the neuron is slightly lower than outside (average - 70mV)

45
Q

potential change (two stages)

A

transmission of info through neuron is realized by the change of potential
1) transmission of info from the exterior through dendrites to the cell body
2) transmission from cell body through the axon out of the neuron

46
Q

excitation of a neuron

A

transmission of info within neuron is not a simple passive act
at level of a neuron, there’s a mechanism of analysis deciding whether to pass/block a message

47
Q

Stages of excitation (2)

A

1) Dendrites
Many post synaptic potentials (strong/weak changes in electrical potential) moving towards the centre
Potentials from dendrites sum up
2) Cells body
If sum is strong enough - the neuron fires
(action potential, always the same strength)

48
Q

2 types of synapses

A

excitatory/ inhibitory synapses

49
Q

excitatory synapse

A

excitatory post synaptic potential. EPSP is a change in polarization moving along the dendrites towards a cell body
EPSP - positive - provokes polarization (decreases polarization)

50
Q

inhibitory synapse

A

IPSP change in polarization moving along dendrites to cell body
IPSP - negative - provokes hyperpolarization (increases polarization)

51
Q

what happens to postsynaptic potentials along the membrane

A

they become smaller and may vanish before the reaching body cell

52
Q

summation

A

post synaptic potentials sum up when meet other post synaptic potentials or if followed by others

53
Q

two types of summation

A

over space/ over time

54
Q

over space summation

A

from different dendrites

55
Q

over time

A

from the same dendrites

56
Q

what happens to potentials in the cells body

A

the free potential is formed and moves toward the proximal part of the axon

57
Q

what happens if the free potential is low (doesn’t reach threshold level)

A

it dies

58
Q

if free potential is high (reaches potential level)?

A

provokes a sudden and massive electric excitation at the proximal part of the axon: the action potential (spike)

59
Q

process of action potential

A

moves along the axon without any loss in its parameters to reach the presynaptic membrane where it produces the release of chemical substance

60
Q

all or none principle (action potential)

A

-amplitude of action potential is independent of amount of current which produced it - large current doesn’t equal large AP
-amplitude is constant for given axon (+30/40mV)
- they either occur fully or not occur

61
Q

propagation of action potential

A

first AP - on the axon hillock
action potentials move down axon towards another cell using saltatory conduction

62
Q

saltatory conduction

A

APs hop along the axon recurring at successive nodes of ranvier -> fast propagation
myelin prevents any charge leakage through the axon

63
Q

Multiple Sclerosis MS

A

neurological condition affecting 10k ppl in uk
symptoms - vision problems/ fatigue/ difficulties with walking
cause - demyelination of axons in the brain and spinal cord

64
Q

SUMMARY

A

two main cells in NS - glia/neurons
Neurons - perform info processing tasks
Neuron basic structure - soma + dendrites + axon
Neurons resting potential = -70mV
stimulated neuron: if depolarisation exceeds threshold, neuron fires an action potential of a constant size

Biological (9 decks)

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