Neurology Week 10 Flashcards
(193 cards)
1
Q
How is the nervous system organized
A
CNS and PNS
- Central Nervous System
- Peripheral Nervous System
2
Q
How many pairs of spinal nerve are in the PNS
A
31
3
Q
How many pairs of cranial nerves are in PNS
A
12
4
Q
How can the peripheral nervous system be subdivided
A
Into 2 divisions
- Afferent
- Efferent
5
Q
What is the afferent division
A
Carries info to CNS
“A in afferent is advancing to CNS”
Consists of (1) sensory & (2) visceral stimuli
6
Q
What is efferent division
A
Transmits info from CNS to effector organs
7
Q
What can the efferent nervous system be divided into
A
Somatic nervous system
Autonomic nervous system
8
Q
What is the somatic nervous system
A
Fibers of motor neurons that supply skeletal muscles
Subjected to voluntary control
9
Q
What is autonomic nervous system
A
Fibers that innervate smooth muscle, cardiac muscle and glands
Involuntary
10
Q
What can the autonomic nervous system be subdivided into
A
Sympathetic and Parasympathetic nervous system
11
Q
What does an autonomic nerve pathway consists of
A
2 Neuron chain which are
(1) Preganglionic neuron
(2) Postganglionic neuron
12
Q
What are Preganglionic neurons
A
Synapses with cell body of postganglionic fiber in a ganglion outside CNS
13
Q
What is postganglionic neuron
A
Sends axons that end on effector organ
14
Q
How are most visceral organs innervated
A
Dually innervated by sympathetic and parasympathetic nervous systems
15
Q
What is dual innervation
A
Innervation of single organ by both branches of autonomic nervous system
16
Q
When does sympathetic dominance occurs
A
Fight or flight
17
Q
When does parasympathetic dominance occurs
A
Rest and digest
18
Q
Where can preganglionic neurons be found with regards to sympathetic innervation
A
Located between segments T1 & L2 of spinal cord
19
Q
What is unique of preganglionic fibers for sympathetic innervation
A
Can synapse with >1 ganglionic neurons
20
Q
What is the distribution of parasympathetic innervation like
A
Innervates organs of 3 main regions
- Cranial
- Trunk
- Pelvic
21
Q
What is the type of fibers of parasympathetic innervation like
A
Long preganglionic
Short postganglionic
22
Q
What is gray matter
A
generic term for collection of cell bodies (soma) in the CNS
23
Q
What is white matter
A
generic term for collection of CNS axons
24
Q
What are the major features that protect CNS from injury
A
Cranium & Vertebral column
Meninges
Cerebrospinal fluid
Blood Brain Barrier
25
What does Meninges consist of
3 meningeal membranes that wrap, protect and nourish CNS
Continuous with spinal meninges
26
What are the different mater found in Meninges
Dura (outer layer)
Arachnoid (middle layer)
Pia (inner layer)
27
Does the brain float in its own special CSF
Yes
28
What is Cerebrospinal Fluid
Shock absorbing liquid
- Surrounds & cushions brain & spinal cord
- Formed by choroid plexuses in ventricles (brain)
29
What is the function of CSF
Cushion delicate neural structures
Support brain
Transport nutrients, chemical messengers & waste products
30
How many ventricles can be found in the brain
4
31
Where can the 4th ventricle be found
Near the central canal of spinal cord
32
What produced meninges & CSF
Ependymal cells of choroid plexuses
33
Where does meninges & CSF circulate
Throughout ventricles
34
Where does meninges & CSF exit
4th ventricle
35
What happens to the meninges & CSF after flowing out of 4th ventricle
Flow in subarachnoid space and is reabsorbed into venous blood
36
How is CSF extracted
Through lumbar puncture from the subarachnoid space
Local anaesthesia is done prior to procedure
Patient can be either lying down to the side or sitting
37
What is the function of BBB
Isolates CNS neural tissue from general circulation
38
How is BBB formed
Formed by network of tight junctions between endothelial cells of CNS capillaries
39
What is BBB
Highly selective BBB that regulates exchanges between blood & brain
- Allows chemical composition of blood and CSF to differ
- Selectively isolate brain from chemicals that could disrupt neural function
40
How is the brain nourished
Dependent on constant delivery of O2 & Glucose by blood
41
Does the brain utilize and store glucose
No. Only uses glucose but cannot store it
42
Does the brain need O2 for energy production
Yes
43
What is the weight of the brain relative to body weight
2%
44
How much CO goes into the brain
13 - 15%
45
What happens if the brain is deprived of O2
Brain damage occurs
46
What are the general functions of CNS
Subconsciously regulate homeostatic responses
Emotions
Voluntary Movement
Perception
Engage in higher cognitive processes
47
What are the componentsof the brain
Brain stem
Cerebellum
Forebrain
- Diencephalon
- hypothalamus
- thalamus
- Cerebrum
- basal nuclei (basal ganglia)
- cerebral cortex
48
What makes up the brain stem
Midbrain, pons, medulla
49
Where can thalamus be found
Medially above hypothalamus
50
Where can basal nuclei be found relative to thalamus
Lateral to thalamus
51
What is the function of cerebral cortex
Sensory perception
Voluntary control of movement
Language
Personality trait
Sophisticated mental events
- thinking
- creativity
52
What is basal nuclei function
Inhibition of muscle tone
coordinating slow sustained movements
suppress useless patterns of movement
53
Where can the central sulcus be found
Between frontal and parietal lobe
54
What are the general functions of nervous system
Sensory
Communicative
Integrative
Motor
Respond to both internal & external stimuli
55
What does the CNS consists of
Brain and spinal cord
56
What does PNS consists of
Nerve fibers
57
Where do most of the cranial nerves originate from
Brain stem
58
How can the spinal cord be divided into from top to bottom
Cervical cord > thoracic cord > lumbar cord > sacral cord
59
Where can coccygeal nerve be found
At the tip of the end of spinal cord
60
How many nerves are found in each of the different spinal cord segments
Cervical - 8
Thoracic - 12
Lumbar - 5
Sacral - 5
Coccygeal - 1
61
Where do the rest of the nerves attached to after the spinal cord
Cauda equina (Horse tail?)
62
What is the 3rd system that ANS can influence
Enteric nervous system which affects digestive organs only
The mini brain of intestines and stomach
63
What is ganglion
Cluster of neuron cell bodies
64
What is the sympathetic division called
Thoracolumbar division
65
What do adrenal medulla only have
preganglionic neuron
66
What is the parasympathetic division called
craniosacral division
67
What is the difference in pre/post-ganglionic neurons between thoracolumbar and craniosacral divisions
Craniosacral divisions have longer pre-ganglionic neurons and shorter post-ganglionic neurons compared to thoracolumbar
68
What does the vagus nerve innervate
Innervates and supplies majority (75%) to the thoracic and abdominal organs
69
What are ventricles in the brain
Fluid filled cavities in the brain
70
What does the thalamus do
Relay sensory inputs to CNS except smell
Motor control function
Degree of consciousness
71
What does hypothalamus do
Homeostatic function
72
What does cerebellum do
Balance & coordination of muscle activity
Enhances muscle tone
73
What does brain stem do
Respiratory function
Vital for survival. If its dead, u dead
74
What does the frontal lobe consists of
Prefrontal cortex & motor cortex
75
What is the purpose of prefrontal cortex
Complex cognitive decision making
Personality
Social behavior
76
What is the parietal lobe used for
Somatosensory processing
77
What is the occipital lobe used for
Visual
78
What is the temporal lobe used for
Memory formation
79
What is the somatotopic map
Relative proportion of somatosensory cortex devoted to reception of sensory input from each area
Distribution of motor output from primary motor cortex to different parts of body
80
How is the distribution of somatotopic map like
Precise distribution is unique to individual
It is use-dependent modification
81
What is somatotopic map also known as
motor and sensory homunculus
82
What is the spinal cord
Long slender cylinder of nerve tissue
83
What does the spinal cord extends to
Extends from the brain stem > vertebral canal > spinal nerves
84
How is the spinal cord protected
Enclosed by protective vertebral column
85
How are the white matter organized
Into tracts to form bundles of nerve fibers with similar function
86
How to differentiate between white and gray matter
H symbol is gray matter, Surrounding is white matter
87
What are dermatomes
Area of skin supplied by single spinal cord level or one side by a single spinal level
88
What can dermatomes be used for
Localizing lesions to specific spinal nerve or level for neurological examination
89
What are myotomes
Portion of skeletal muscle innervated by single spinal cord level or one side by single spinal nerve
90
Are each skeletal muscle usually innervated by nerves from >1 spinal cord level
Yes
91
How are myotomes used
Likewise to dermatomes, used to test movements at successive joints to help localize nerve or spinal cord lesions
92
How does the afferent sensory nerves enter the spinal nerves
Through posterior ramus to dorsal root
93
How does the efferent sensory nerves leave the spinal nerves
Through the ventral root to anterior ramus
94
What does the posterior and anterior rami supply
Supplies spinal nerves T1 - L2
95
What are nerve plexuses
Network of nerves that come together and then redistribute themselves out with different distribution of nerves into limbs
96
Is nerve plexuses somatic or visceral
Both
97
What is an advantage of using nerve plexuses instead of single spinal nerve
Less likely to cause total paralysis of muscle innervated by nerves from that plexus
98
What are the nerves like when it exists the plexus
Contains fibers from different spinal nerves
99
Does the plexus affect dermatomes sensing
No. It will eventually branch out to its respective areas
100
The BBB is formed by network of tight junctions between endothelial cells of CNS arterioles. True or False
False
101
The dorsal root of spinal cord carry ___ signal while ventral root carry ___ signal
Sensory; motor
102
What are neurons
basic functional units / conducting cells of nervous system
103
What do neurons do
Processes and transmits info in electrical & chemical form
104
What is the structure of neurons
Cell body (soma)
Short, branched dendrites
Long, single axon
105
What is the soma
contains organelles essential for survival (nucleus, mitochondria, RER)
106
What are the short branched dendrites
highly branched and receives info from other neurons
107
What is the long single axon
Carries electrical signal (action potential) to target
108
What are the different neurons
bipolar, unipolar and mulitpolar
109
What is the bipolar neuron
bipolar neuron with 2 processes separated by cell body
110
what is unipolar neuron
unipolar neuron have single elongated process with cell body located off to the side
111
what is multipolar neuron
multipolar neurons have >2 processes - single axon & multiple dendrites
112
What does the neuroglia do
Supports neuronal function
113
What % of the NS is neuroglia
50%
114
What are the different neuroglia
Astrocytes
Myelinating glia
Microglia
Ependymal cells
MAME
115
What do ependymal cells do
produces CSF
116
what does microglia do
phagocytic role to remove cell debris, wastes
modified immune cells
117
What are the 2 sub-types of myelinating glia
oligodendocytes (CNS)
schwann cells (PNS)
118
What do astrocytes do
regulates chemical content of extracellular space
119
Are neurons and muscle cells excitable tissues
yes
120
What happens when neurons and muscle cells are excited
Produced electrical signals
neurons - receive, process, initiate and transmit messages
muscles - initiate contraction
121
Are electrical signals important to function of NS
yes
122
What are the different stages of neural comms
polarization
depolarization
repolarization
hyperpolarization
123
How are electrical signals produced
By changes in ion movement across plasma membrane
- event triggers membrane potential change
- alters membrane permeability = alters ion flow across membrane
124
What are the gated channels in neurons
voltage gated
chemically gated
mechanically gated
thermally gated
125
what are graded potentials
local changes in membrane potential
- occurs in varying degrees of magnitude
- stronger trigger = larger resultant graded potential
126
How are graded potentials spread
By passive current flow
- current = flow of electrical charges
- resistance = resistance to electrical charge movement
127
How do graded potentials die out
Over short distances
128
What are action potentials
Brief, rapid, large changes in membrane potential
129
Is it possible for the action potential to reverse
only if it is graded potential
130
What happens inside excitable cells during action potential
Inside of cell transiently becomes more positive than outside
131
What conditions lead to an action potential
marked changes in membrane permeability & ion movement
132
What channels are involved for action potential
Voltage gated Na+ & K+ channels
133
How are action potentials relayed through neuron
1) Dendrites receives incoming signals from other neurons (Input)
2) Soma initiates action potential through axon hillock (Trigger)
3) Axon conducts AP in undiminishing fashion over long distances (Conducting)
4) Axon terminals releases neurotransmitters that influences other cells (Output)
134
What is the purpose of refractory period
Ensures one way propagation of AP
Limits frequency of AP
135
Can an AP be initiated in region that has just undergone an AP
No
136
How is the fashion in which an AP occurs
All or nothing
137
What is the advantage of an AP acting in 'all or nothing' fashion
Allows discrimination of stimuli & weak stimuli do not initiate AP (No hypersensitivity)
138
How does one measure the strength of a stimulus
Frequency of AP (magnitude of AP is the same each time)
139
What does myelination do
Increase speed of conduction of AP
140
What does the fiber diameter do
Influences velocity of AP propagation
141
What is myelin
Thick layer of lipids
142
What is the function of myelin
Insulates electrical transmission across axon
143
What are the 2 forms of conduction
Contiguous & Saltatory conduction
144
What are synapses
junction between neurons
145
what are electrical synapses
neurons connected directly by gap junctions
146
what are chemical synapses
chemical messenger transmits info 1 way across space between 2 neurons
147
What makes the majority of synapses in human NS
chemical synapses
148
What is the process of synaptic transmission
Depolarization
Influx of Ca2+
Docking
Release of neurotransmitter
Binding of neurotransmitter to receptor
149
What do drugs & diseases do to synapses
modify synaptic transmission by altering its mechanism
150
How are neurons linked
converging and diverging pathways
151
what are converging pathways of a neuron
given neuron may have many other neurons synapsing on it
152
what are diverging pathways of a neuron
branching axon terminals so 1 cell synapse influences other cells
153
What are the different neurotransmitters
Acetylcholine
Dopamine
Glutamate
Gamma-aminobutyric acid (GABA)
154
What does GABA do
primary inhibitory neurotransmitter in CNS (IPSP)
155
What does glutamate do
primary exhibitory neurotransmitter in CNS (EPSP)
156
What does dopamine do
Involved in many pathways in CNS
- muscle movement
- reward pathway
157
What is the effect of ANS on lungs
sympathetic
- Dilates bronchioles
- inhibits mucus secretion
parasympathetic
- constricts bronchioles
- stimulates mucus secretion
158
What is the effect of ANS on digestive tract
sympathetic
- contracts sphincters to prevent forward movement of contents
- decreased motility
- inhibits digestive secretions
vice versa for parasympathetic
159
What is the effect of ANS on urinary bladder
sympathetic = relaxes
parasympathetic = contracts (emptying)
160
What is the effect of ANS on eyes
sympathetic = dilates eye and adjust for far vision
parasympathetic = constricts and adjust for near vision
161
What is the effect of ANS on sweat glands
sympathetic = increased secretion by sweat glands for cooling body
parasympathetic = none
162
What is the effect of ANS on salivary glands
sympathetic = small volume of thick salvia rich in mucus
parasympathetic = large volume of watery saliva rich in enzymes
163
What is the effect of ANS on adrenal medulla
sympathetic = stimulates epinephrine & norepinephrine
parasympathetic = none
164
What are the neurotransmitters produced by ANS
Sympathetic
- preganglionic = ACh
- postganglionic = NE
Parasympathetic
- preganglionic = ACh
- postganglionic = ACh
165
What are the origin of ganglionic fibers in sympathetic system
preganglionic = thoracic & lumbar region of spinal cord
postganglionic = sympathetic ganglion chain / collateral ganglia
166
Where can collateral ganglia be found
Halfway between spinal cord & effector organs
167
What are the origin of ganglionic fibers in parasympathetic system
preganglionic = brain & sacral region of spinal cord
postganglionic = terminal ganglia (in or near effector organs)
168
What is EPSPs
Excitatory Post-Synaptic Potentials
169
What is IPSPs
Inhibitory Post-Synaptic Potentials
170
What happens when voltage in neuron exceeds threshold at -55mV
Action potential occurs
171
WWhat are the stages of an action potential
1) Resting - Na+ & K+ channels closed
2) Stimulus - Na+ channels open & Na+ flows in
3) Threshold - Goes past -55mV, more Na+ channels open (Depolarization)
4) Peak - Na+ channels close, K+ channels open (30mV)
5) Repolarization - K+ rush out
6) Overshoot - membrane potential goes down to -90mV, K+ channels close, Na+ K+ pump restores initial conditions & resting potential
172
What ion is the main driver of membrane potential
K+
173
What is the difference between contiguous & saltatory conduction
Saltatory conduction occurs at axon with myelin sheaths whereas contiguous conduction does not
174
where is AP initiated
axon hillock
175
What do EPSPs and IPSPs do
EPSP = brings graded potential closer to threshold
vice versa for IPSPs
176
what channel is responsible for refractory period
Na+ channels
177
outward movement of ___ ions rapidly restores negative resting potential
K+
178
what ion is the resting membrane most permeable to
K+
179
what is the life cycle of CSF
- produced by ependymal cells of choroid plexuses
- circulate throughout ventricles
- exit 4th ventricle
- flow in subarachnoid space
- reabsorbed into venous blood
180
what organ only has preganglionic nerve
adrenal gland
181
where does spinal cord end
L1 vertebrae
182
What does sympathetic & parasympathetic ganglionic fibers originate from
sympathetic = thoracic & lumbar regions of spinal cord
parasympathetic = brain & sacral region of spinal cord
183
what does the grey and white matter contain
grey = soma collection
white = axon axon collection
184
how are graded potentials spread
passive current flow
185
visceral motor nuclei in the brainstem & spinal cord are known as
preganglionic neurons
186
bundles of axons in peripheral NS are known as
nerve fibers
187
which neural cell has phagocytotic properties
microglia
188
excitatory neurotransmitters cause ____, inhibitory neurotransmitters cause ___
depolarization; hyperpolarization
189
gray matter of the spinal cord consist of
neuronal cell bodies & unmyelinated axons
190
what does damage to basal nuclei lead to
difficulty starting voluntary movement & decreased muscle tone
191
which area acts as a filter for sensory info coming into sensory cortex
pons
192
all ___ pathways send info to the ___ when motor commands are issued
motor / cerebellum
193
translation of a stimulus into AP is known as
transduction
