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1st Year Med > CNS/Nervous System > Flashcards

CNS/Nervous System Flashcards

1
Q

what does the CNS briefly do?

A

receives and integrates info from rest of body, coordinates activity of rest of body

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2
Q

what nerves does the PNS include?

A

all cranial nerves except 2 and optic

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3
Q

name the cells found in the nervous system

A

neurons
glial cells
astrocytes
schwann cells
oligodendrocytes
microglia
ependymal cells

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4
Q

name the components of a neuron

A

dendrites, nucleus, axon, cell body, myelin sheath, Schwann cell, node of ranvier, axon terminal

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5
Q

describe the variations neurons can have

A

unipolar, bipolar or multipolar

1-1000s of connections

myelinated or not (speeds up transmission)

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6
Q

what do astrocytes do?

A

give structural support, form blood brain barrier
involved in nutrient supply to neurons in CNS

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7
Q

what do schwann cells and ogliodendrocytes do?

A

enables fast signalling
neuron support and myelin formation in the CNS (ogliodendrocytes) and PNS (schwann cells)

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8
Q

what do ependymal cells do?

A

promote circulation, production of CSF

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9
Q

what do microglial cells do?

A

immune protection (phagocytic)

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10
Q

what is the difference between grey and white matter nervous tissue?

A

grey - more cell bodies, dendrites, axon termini, glial cells and blood vessels
white - more axons (myelinated), glial cells (ogliodendrocytes) and blood vessels

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11
Q

name the lobes of the brain

A

frontal lobe, pre central gyrus, central sulcus, postcentral gyrus, parietal lobe, occipital lobe, temporal lobe (deep limbic lobe underneath)

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12
Q

what are the 3 subsections of the brain stem?

A

midbrain, pons, medulla

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13
Q

what cranial nerves emerge from the brain stem?

A

3-12

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14
Q

what does the medulla contain?

A

ANS functions and reflex centres (e.g vomiting)

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15
Q

what is the cerebrum composed of?

A

cortex + white matter

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16
Q

what is the function of the prefrontal cortex?

A

cognition, personality, behaviour, mood

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17
Q

name some of the deep structures in the brain and their functions

A

limbic system: hippocampus (memory) and amygdala (emotion)
hypothalamus (regulates body function)
thalamus (sensory relay centre between spinal cord and cerebral cortex)
basal ganglia (movement control)

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18
Q

what is the function of white matter tracts?

A

communication between brain parts (e.g corpus callosum)

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19
Q

describe the characteristics of brain central hemispheres

A

some areas have different functions in L and R but mostly functional
example: language production/comprehension most commonly in L

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20
Q

what is the spinal cord?

A

direct extension of brain stem downwards

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21
Q

what are the 4 spinal cord regions?

A

cervical, thoracic, lumbar, sacral

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22
Q

what do spinal nerves do?

A

each level allows input/output to specific parts of the body
can be sensory, motor or autonomic

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23
Q

name 2 examples of spinal nerve functions

A

C1-5: breathing
L3-S1: knee/foot movement

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24
Q

where does sympathetic and parasympathetic tone originate in spinal nerves?

A

sympathetic - T1-12
parasympathetic - cranial nerves and S4

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25
Q

what differences do each spinal nerve types have from eachother?

A

input/output amount
grey:white matter ratio
shapes

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26
Q

describe the anatomical direction of where input and output enters and leaves the spinal cord

A

input - dorsal
output - ventral

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27
Q

name the 3 regions of the spinal cord

A

conus medullaris, cauda equina, filum terminale

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28
Q

what are spinal cord tracts?

A

bundles of nerve fibres running up/down spinal cord

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29
Q

what does spinal tract decussation mean?

A

crossing over of tracts (same -> opposite side)

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30
Q

what are the meninges?

A

3 membrane layers surrounding the brain/spinal cord

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31
Q

name the 3 meninges layers and a brief structural description

A

dura mater (fibrous CT), arachnoid (membrane), pia mater (membrane)

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32
Q

what is between the spaces between the meninges layers and what do they contain?

A

epidural (extradural) between skull and dura - can contain haematoma
subdural between dura and arachnoid - can contain haematoma
subarachnoid space between arachnoid and pia mater - contains CSF, cerebral arteries/veins

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33
Q

what is meningitis and how does it form? what can it cause?

A

inflammation of pia mater & arachnoid meter (subarachnoid space)
usually viral/bacterial
can cause brain damage: cerebral oedema (raised inter cranial pressure can cause herniation)

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34
Q

where does CSF fill?

A

ventricles (brain) and subarachnoid space of meninges (brain/SC)

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35
Q

name the 5 ventricles of the brain that CSF travels through

A

lateral ventricle, inter ventricular foramen, third ventricle, midbrain aqueduct, fourth ventricle

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36
Q

what are the functions of CSF?

A

cushions brain against impact/movement
provides brain with stable chemical environment
nutrient/waste exchange between nervous system and blood

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37
Q

how is CSF produced and reabsorbed?

A

produced by choroid plexus in lateral/4th ventricles and resorbed into venous system by arachnoid granulations

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38
Q

how is CSF circulated and what happens if excess/insufficient flow?

A

circulation driven by new production of CSF
excess/insufficiency = hydrocephalus

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39
Q

describe the composition of CSF

A

clear/colourless liquid, very few cells, low proteins levels, different electrolyte levels to plasma

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40
Q

what is the BBB and what does it do?

A

several features that prevent harmful substances entering CNS from blood

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41
Q

explain the structure of capillaries in the nervous system

A

tight junctions between endothelial cells restrict movement
thick continuous BM
astrocyte processes cover vessel

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42
Q

how do ependymocytes contribute to the BBB?

A

the cells line ventricles and spinal canal
tight junctions restrict movement

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43
Q

why do some areas of the BBB have higher permeability?

A

sensory functions - medulla needs small amount of toxin detection to initiate vomiting reflex
secretory functions - pituitary gland for secreting hormones

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44
Q

describe the detailed function of the BBB?

A

keeps out toxins, pathogens
stops fluctuations of ions, nutrients and metabolite concentrations in CNS

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45
Q

what substances are permeable across the BBB?

A

water
small lipophilic molecules, (gases)
active transported substances (glucose/amino acids)

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46
Q

what are the 5 general functions of the nervous system?

A

communication
internal event regulation
behavioural organisation
storage of info
sensations/perceptions/emotions

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47
Q

how many pairs of spinal nerves are there?
how are they named?

A

31 pairs
named after the level of spinal cord they arise from

48
Q

where do cranial nerves originate and where do they supply?

A

originate in brain/brainstem
supplies head/neck structures

49
Q

what do somatic and visceral mean?

A

somatic - cell of the body (not germ line)
visceral - internal organs in body cavities

50
Q

what does afferent and efferent mean?

A

afferent - arrived into brain/spinal cord
efferent - exits brain/spinal cord

51
Q

where do somatic and visceral efferent signals act?

A

somatic - skeletal muscle
visceral - smooth muscle, glands, cardiac muscle

52
Q

what is the function of the cerebellum?

A

controls movement, coordination, precision, integration

53
Q

what is the anatomical division name for the cerebrum?

A

telencephalon

54
Q

what is the anatomical division name for the thalamus/hypothalamus?

A

diencephalon

55
Q

what is the anatomic division term for the midbrain?

A

mesencephalon

56
Q

what is the anatomic division term for the hindbrain?

A

rhombencephalon

57
Q

what is the function of the thalamus/hypothalamus?

A

thalamus - relay station for sensory/motor systems, regulates sleep/conciousness
hypothalamus - regulates endocrine system via pituitary gland and thermoregulation

58
Q

what does the frontal lobe control?

A

executive functions - long term memory, speech, movement, personality

59
Q

what does the parietal lobe control?

A

sensory integration, language interpretation, spacial/visual perception

60
Q

what does the occipital lobe control?

A

visual processing (colour/light)

61
Q

what does the temporal lobe control?

A

primary auditory complex, memory, understanding language

62
Q

what is the function of the node(s) of ranvier?

A

allow faster signal transmission

63
Q

what does the myelin sheath do?

A

insulates the nerve fibres (axons)

64
Q

what is the hole in the middle of the brain/top of spinal cord called? and what cells surround it?

A

central canal
surrounded by ependymal cells

65
Q

what does the cortical homunculus show?

A

the disproportionate areas of how the sensory/motor functions are represented in the brain

66
Q

what are some clinical conditions that affect the CNS/nervous system?

A

stroke (transient ischaemic attack)
dementia
infections
trauma
congenital
neurology/neurosurgery
GCS (glasgow coma scale)

67
Q

where is the conus medullaris located?

A

L1/2

68
Q

what is the cauda equina and where is it located?

A

nerve rootlets/fibres, located L2-5 at the lumbar cistern (in subarachnoid space)

69
Q

what do autonomic efferent nuclei do in the spinal cord and where are they located?

A

mediate the sympathetic nervous system
located T1-L2

70
Q

explain the process of a nerve impulse signal passing through the spinal cord

A

afferent info (visceral/somatic) enters dorsally into dorsal horn, travels up to brain for process/interpretation
info sent back down into ventral horn, and efferent signals sent to muscles/glands through ventral root

71
Q

name the types of nuclei present in the spinal cord and whether they are ventral (V) or dorsal (D)

A

visceral sensory nuclei (D)
somatic sensory nuclei (D)
autonomic efferent nuclei (V)
somatic motor nuclei (V)

72
Q

name the general structural features of the spinal cord

A

vertebra body, spinous processes, transverse processes, spinal nerve, dorsal/ventral roots

73
Q

name the 2 layers of the dura meter

A

periosteal and meningeal

74
Q

what are sensory/motor neuron regions in the spinal cord called?

A

sensory - dermatones
motor - myotones

75
Q

why doesn’t C1 have a dermatone associated with it?

A

C1 has no dorsal (sensory) root, only a motor root

76
Q

what characteristic does a pseudounipolar neuron have?

A

has 1 extention from its cell body and splits into 2 branches - one goes peripherally and one centrally

77
Q

what characterisitic does a somatic multipolar neuron have?

A

single axon and many dendrites

78
Q

what characteristic does an autonomic multi-polar neuron have?

A

synapse between 2 neurons

79
Q

what do pseudounipolar nerves act on?

A

sensory receptors

80
Q

what do multipolar neurons act on?

A

effector organs, skeletal striated muscle

81
Q

what do autonomic multipolar neurons act on?

A

modified cardiac muscle, smooth involuntary muscle, glands

82
Q

what is the general function of cranial nerves?

A

provide sensory and motor supply to head and neck

83
Q

what is cranial nerve 1 and what does it control?

A

olfactory - smell

84
Q

what is cranial nerve 2 and what does it control?

A

optic - vision

85
Q

what is cranial nerve 3 and what does it control?

A

oculomotor - eye movements

86
Q

what is cranial nerve 4 and what does it control?

A

trochlear - eye movements

87
Q

what is cranial nerve 5 and what does it control?

A

trigeminal - motor to muscles of mastication and general sensory to the face

88
Q

what is cranial nerve 6 and what does it control?

A

abducens - eye movements

89
Q

what is cranial nerve 7 and what does it control?

A

facial - muscles of facial expression

90
Q

what is cranial nerve 8 and what does it control?

A

vestibulocochlear - hearing/balance

91
Q

what is cranial nerve 9 and what does it control?

A

glossopharyngeal - swallowing/taste

92
Q

what is cranial nerve 10 and what does it control?

A

vagus - wandering nerve supplying heart/lungs/gut

93
Q

what is cranial nerve 11 and what does it control?

A

spinal accessory - neck muscles

94
Q

what is cranial nerve 12 and what does it control?

A

hypoglossal - tongue muscles

95
Q

where is the sympathetic and parasympathetic visceral efferent fibres located?

A

sympathetic - thoracolumnar, T1-L2
parasympathetic - craniosacral, S2-4

96
Q

what is electrical signalling?

A

movement of electrical charge usually by ions

97
Q

what is the definition of an impulse?

A

a wave of altered charge across nerve cell that sweeps along axon
(aka. depolarisation and AP)

98
Q

explain what causes a general action potential

A

at rest, ion conc. inside and outside the cell is different (maintained by ion pumps in plasma membrane)
when nerve cell is stimulated, Na ion channels open causing an infux of Na ions resulting in depolarisation of the membrane, generating an action potential

99
Q

explain the mechanisms of creating an impulse in a neuron

A

Na+ ion channels open, Na+ enters (depolarisation)
K+ ion channels open in response to depolarisation, Na+ channels close, and K+ ions leave cell (repolarisation)
an overshoot (hyperpolarisation) occurs
K+ ions close and Na+ channels reset, membrane returns to resting potential

100
Q

what is the refractory period?

A

a period of time following a nerve impulse in a neuron where an AP cannot be created

101
Q

what dendritic inputs can cause a change in action potential chance?

A

excitory pre-synaptic potentials (EPSPs)
inhibitory pre-synaptic potentials (IPSPs)

102
Q

what effect can IPSPs and EPSPs have on action potential formation?

A

ESPSs increase chance
IPSPs decrease chance

103
Q

what is spacial summation?

A

summation of inputs from different areas of cell (different dendrites)

104
Q

what is temporal summation?

A

input occurs multiple times from the same area/dendrite
(repeated inputs in short time -> greater summation)

105
Q

can AP magnitude or AP frequency vary? if so what is encoded by it?

A

magnitude - doesn’t vary
frequency - varies, signal intensity controlled by AP frequency (firing rate)

106
Q

how do neurons transfer AP across different neurons in the pathway?

A

crosses a synapse (gap) between neurons

107
Q

describe a simple reflex arc example for a pain response

A

stimulus (pain) -> receptor (pain receptor in skin) -> sensory neuron -> CNS -> relay neuron -> CNS -> motor neuron -> effector (muscles) -> response (move away from pain source)

108
Q

what do chemical signals do in terms of signal relay and how does this happen?

A

chemical signals transmit signals across synapse
they’re released when AP reaches pre-synaptic neuron termini and bind to receptors on dendrites of post-synaptic neuron

109
Q

how can neurotransmitters differ from eachother in functions and pathways?

A

different NTs associated with different nervous system functions (memory/movement)
excitatory (promote AP) or inhibitory (inhibit AP)
different drugs act on different NT signalling

110
Q

describe the derivatives of amino acid NTs with examples

A

glutamate - main excitatory NTs in CNS
GABA - main inhibitory NTs in CNS

111
Q

what are catecholamine NTs derived from and give an example

A

derived from Tyrosine
example - dopamine, seratonin

112
Q

what is acetylcholine NTs derived from and where are they useful?

A

derived from choline
useful at neuromuscular junctions

113
Q

give an example of peptide NTs

A

substance P, endorphins

114
Q

explain how GABA works to inhibit an AP

A

GABA-A receptor is an ion channel receptor
binding of GABA to receptor causes conf. change opening ion channel, where ions move along conc. gradient
GABA released from presynaptic neuron into synapse
GABA receptor in post-synaptic neuron membrane
GABA-A receptor = Cl- ion channel, Cl- ions enter and hyperpolarises neuron, making it harder to reach AP

115
Q

explain how acetylcholine functions at a neuromuscular junction

A

nAChR = sodium ion channel receptor, ACh binding allows Na+ entry
Na+ influx causes depolarisation of muscle cell membrane, initiating contraction
Acetylcholinesterase in cleft removes ACh

116
Q

how does electrical signalling work in gap junctions?

A

connexin proteins form connections with channel
ions carry charge from one cell to another

117
Q

name 2 instances where electrical signalling via gap junctions is used

A

‘electrical synapses’ between neurons
cardiac myocytes

1st Year Med (52 decks)

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