CNS/Nervous System Flashcards
(117 cards)
1
Q
what does the CNS briefly do?
A
receives and integrates info from rest of body, coordinates activity of rest of body
2
Q
what nerves does the PNS include?
A
all cranial nerves except 2 and optic
3
Q
name the cells found in the nervous system
A
neurons
glial cells
astrocytes
schwann cells
oligodendrocytes
microglia
ependymal cells
4
Q
name the components of a neuron
A
dendrites, nucleus, axon, cell body, myelin sheath, Schwann cell, node of ranvier, axon terminal
5
Q
describe the variations neurons can have
A
unipolar, bipolar or multipolar
1-1000s of connections
myelinated or not (speeds up transmission)
6
Q
what do astrocytes do?
A
give structural support, form blood brain barrier
involved in nutrient supply to neurons in CNS
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)
8
Q
what do ependymal cells do?
A
promote circulation, production of CSF
9
Q
what do microglial cells do?
A
immune protection (phagocytic)
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
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)
12
Q
what are the 3 subsections of the brain stem?
A
midbrain, pons, medulla
13
Q
what cranial nerves emerge from the brain stem?
A
3-12
14
Q
what does the medulla contain?
A
ANS functions and reflex centres (e.g vomiting)
15
Q
what is the cerebrum composed of?
A
cortex + white matter
16
Q
what is the function of the prefrontal cortex?
A
cognition, personality, behaviour, mood
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)
18
Q
what is the function of white matter tracts?
A
communication between brain parts (e.g corpus callosum)
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
20
Q
what is the spinal cord?
A
direct extension of brain stem downwards
21
Q
what are the 4 spinal cord regions?
A
cervical, thoracic, lumbar, sacral
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
23
Q
name 2 examples of spinal nerve functions
A
C1-5: breathing
L3-S1: knee/foot movement
24
Q
where does sympathetic and parasympathetic tone originate in spinal nerves?
A
sympathetic - T1-12
parasympathetic - cranial nerves and S4
25
what differences do each spinal nerve types have from eachother?
input/output amount
grey:white matter ratio
shapes
26
describe the anatomical direction of where input and output enters and leaves the spinal cord
input - dorsal
output - ventral
27
name the 3 regions of the spinal cord
conus medullaris, cauda equina, filum terminale
28
what are spinal cord tracts?
bundles of nerve fibres running up/down spinal cord
29
what does spinal tract decussation mean?
crossing over of tracts (same -> opposite side)
30
what are the meninges?
3 membrane layers surrounding the brain/spinal cord
31
name the 3 meninges layers and a brief structural description
dura mater (fibrous CT), arachnoid (membrane), pia mater (membrane)
32
what is between the spaces between the meninges layers and what do they contain?
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
33
what is meningitis and how does it form? what can it cause?
inflammation of pia mater & arachnoid meter (subarachnoid space)
usually viral/bacterial
can cause brain damage: cerebral oedema (raised inter cranial pressure can cause herniation)
34
where does CSF fill?
ventricles (brain) and subarachnoid space of meninges (brain/SC)
35
name the 5 ventricles of the brain that CSF travels through
lateral ventricle, inter ventricular foramen, third ventricle, midbrain aqueduct, fourth ventricle
36
what are the functions of CSF?
cushions brain against impact/movement
provides brain with stable chemical environment
nutrient/waste exchange between nervous system and blood
37
how is CSF produced and reabsorbed?
produced by choroid plexus in lateral/4th ventricles and resorbed into venous system by arachnoid granulations
38
how is CSF circulated and what happens if excess/insufficient flow?
circulation driven by new production of CSF
excess/insufficiency = hydrocephalus
39
describe the composition of CSF
clear/colourless liquid, very few cells, low proteins levels, different electrolyte levels to plasma
40
what is the BBB and what does it do?
several features that prevent harmful substances entering CNS from blood
41
explain the structure of capillaries in the nervous system
tight junctions between endothelial cells restrict movement
thick continuous BM
astrocyte processes cover vessel
42
how do ependymocytes contribute to the BBB?
the cells line ventricles and spinal canal
tight junctions restrict movement
43
why do some areas of the BBB have higher permeability?
sensory functions - medulla needs small amount of toxin detection to initiate vomiting reflex
secretory functions - pituitary gland for secreting hormones
44
describe the detailed function of the BBB?
keeps out toxins, pathogens
stops fluctuations of ions, nutrients and metabolite concentrations in CNS
45
what substances are permeable across the BBB?
water
small lipophilic molecules, (gases)
active transported substances (glucose/amino acids)
46
what are the 5 general functions of the nervous system?
communication
internal event regulation
behavioural organisation
storage of info
sensations/perceptions/emotions
47
how many pairs of spinal nerves are there?
how are they named?
31 pairs
named after the level of spinal cord they arise from
48
where do cranial nerves originate and where do they supply?
originate in brain/brainstem
supplies head/neck structures
49
what do somatic and visceral mean?
somatic - cell of the body (not germ line)
visceral - internal organs in body cavities
50
what does afferent and efferent mean?
afferent - arrived into brain/spinal cord
efferent - exits brain/spinal cord
51
where do somatic and visceral efferent signals act?
somatic - skeletal muscle
visceral - smooth muscle, glands, cardiac muscle
52
what is the function of the cerebellum?
controls movement, coordination, precision, integration
53
what is the anatomical division name for the cerebrum?
telencephalon
54
what is the anatomical division name for the thalamus/hypothalamus?
diencephalon
55
what is the anatomic division term for the midbrain?
mesencephalon
56
what is the anatomic division term for the hindbrain?
rhombencephalon
57
what is the function of the thalamus/hypothalamus?
thalamus - relay station for sensory/motor systems, regulates sleep/conciousness
hypothalamus - regulates endocrine system via pituitary gland and thermoregulation
58
what does the frontal lobe control?
executive functions - long term memory, speech, movement, personality
59
what does the parietal lobe control?
sensory integration, language interpretation, spacial/visual perception
60
what does the occipital lobe control?
visual processing (colour/light)
61
what does the temporal lobe control?
primary auditory complex, memory, understanding language
62
what is the function of the node(s) of ranvier?
allow faster signal transmission
63
what does the myelin sheath do?
insulates the nerve fibres (axons)
64
what is the hole in the middle of the brain/top of spinal cord called? and what cells surround it?
central canal
surrounded by ependymal cells
65
what does the cortical homunculus show?
the disproportionate areas of how the sensory/motor functions are represented in the brain
66
what are some clinical conditions that affect the CNS/nervous system?
stroke (transient ischaemic attack)
dementia
infections
trauma
congenital
neurology/neurosurgery
GCS (glasgow coma scale)
67
where is the conus medullaris located?
L1/2
68
what is the cauda equina and where is it located?
nerve rootlets/fibres, located L2-5 at the lumbar cistern (in subarachnoid space)
69
what do autonomic efferent nuclei do in the spinal cord and where are they located?
mediate the sympathetic nervous system
located T1-L2
70
explain the process of a nerve impulse signal passing through the spinal cord
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
name the types of nuclei present in the spinal cord and whether they are ventral (V) or dorsal (D)
visceral sensory nuclei (D)
somatic sensory nuclei (D)
autonomic efferent nuclei (V)
somatic motor nuclei (V)
72
name the general structural features of the spinal cord
vertebra body, spinous processes, transverse processes, spinal nerve, dorsal/ventral roots
73
name the 2 layers of the dura meter
periosteal and meningeal
74
what are sensory/motor neuron regions in the spinal cord called?
sensory - dermatones
motor - myotones
75
why doesn't C1 have a dermatone associated with it?
C1 has no dorsal (sensory) root, only a motor root
76
what characteristic does a pseudounipolar neuron have?
has 1 extention from its cell body and splits into 2 branches - one goes peripherally and one centrally
77
what characterisitic does a somatic multipolar neuron have?
single axon and many dendrites
78
what characteristic does an autonomic multi-polar neuron have?
synapse between 2 neurons
79
what do pseudounipolar nerves act on?
sensory receptors
80
what do multipolar neurons act on?
effector organs, skeletal striated muscle
81
what do autonomic multipolar neurons act on?
modified cardiac muscle, smooth involuntary muscle, glands
82
what is the general function of cranial nerves?
provide sensory and motor supply to head and neck
83
what is cranial nerve 1 and what does it control?
olfactory - smell
84
what is cranial nerve 2 and what does it control?
optic - vision
85
what is cranial nerve 3 and what does it control?
oculomotor - eye movements
86
what is cranial nerve 4 and what does it control?
trochlear - eye movements
87
what is cranial nerve 5 and what does it control?
trigeminal - motor to muscles of mastication and general sensory to the face
88
what is cranial nerve 6 and what does it control?
abducens - eye movements
89
what is cranial nerve 7 and what does it control?
facial - muscles of facial expression
90
what is cranial nerve 8 and what does it control?
vestibulocochlear - hearing/balance
91
what is cranial nerve 9 and what does it control?
glossopharyngeal - swallowing/taste
92
what is cranial nerve 10 and what does it control?
vagus - wandering nerve supplying heart/lungs/gut
93
what is cranial nerve 11 and what does it control?
spinal accessory - neck muscles
94
what is cranial nerve 12 and what does it control?
hypoglossal - tongue muscles
95
where is the sympathetic and parasympathetic visceral efferent fibres located?
sympathetic - thoracolumnar, T1-L2
parasympathetic - craniosacral, S2-4
96
what is electrical signalling?
movement of electrical charge usually by ions
97
what is the definition of an impulse?
a wave of altered charge across nerve cell that sweeps along axon
(aka. depolarisation and AP)
98
explain what causes a general action potential
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
explain the mechanisms of creating an impulse in a neuron
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
what is the refractory period?
a period of time following a nerve impulse in a neuron where an AP cannot be created
101
what dendritic inputs can cause a change in action potential chance?
excitory pre-synaptic potentials (EPSPs)
inhibitory pre-synaptic potentials (IPSPs)
102
what effect can IPSPs and EPSPs have on action potential formation?
ESPSs increase chance
IPSPs decrease chance
103
what is spacial summation?
summation of inputs from different areas of cell (different dendrites)
104
what is temporal summation?
input occurs multiple times from the same area/dendrite
(repeated inputs in short time -> greater summation)
105
can AP magnitude or AP frequency vary? if so what is encoded by it?
magnitude - doesn't vary
frequency - varies, signal intensity controlled by AP frequency (firing rate)
106
how do neurons transfer AP across different neurons in the pathway?
crosses a synapse (gap) between neurons
107
describe a simple reflex arc example for a pain response
stimulus (pain) -> receptor (pain receptor in skin) -> sensory neuron -> CNS -> relay neuron -> CNS -> motor neuron -> effector (muscles) -> response (move away from pain source)
108
what do chemical signals do in terms of signal relay and how does this happen?
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
how can neurotransmitters differ from eachother in functions and pathways?
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
describe the derivatives of amino acid NTs with examples
glutamate - main excitatory NTs in CNS
GABA - main inhibitory NTs in CNS
111
what are catecholamine NTs derived from and give an example
derived from Tyrosine
example - dopamine, seratonin
112
what is acetylcholine NTs derived from and where are they useful?
derived from choline
useful at neuromuscular junctions
113
give an example of peptide NTs
substance P, endorphins
114
explain how GABA works to inhibit an AP
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
explain how acetylcholine functions at a neuromuscular junction
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
how does electrical signalling work in gap junctions?
connexin proteins form connections with channel
ions carry charge from one cell to another
117
name 2 instances where electrical signalling via gap junctions is used
'electrical synapses' between neurons
cardiac myocytes
