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HUBS 191 > Human Movement and Sensation 2 > Flashcards

Human Movement and Sensation 2 Flashcards

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1
Q

What does the Central Nervous System consist of?

A

Brain and spinal cord

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2
Q

What does the peripheral nervous system consist of?

A

Peripheral nerves

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3
Q

What is composed of neurons and glia?`

A

All parts of the CNS and PNS

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4
Q

What are neurons?

A

Nerve cells

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5
Q

What is the purpose of Neurons?

A

Cells specialised for transmission of information

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6
Q

What are the functions of the glia?

A

Support for neurons

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7
Q

What are the structures of the neuron? (4)

A

Dendrites
Cell body
Axon
Axon terminal

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8
Q

What is the function of a dendrite?

A

Recieve input
Send information to the cell body

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9
Q

What is the function of the cell body?

A

Contains nucleus and organelles
Sums input

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10
Q

What is the function of the Axon?

A

Carries electrical impulses
May or may not be myelinated

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11
Q

What is the function of the axon terminal?

A

Terminal end of the axon for neurotransmitter release

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12
Q

What is a group of cell bodies called? (CNS)

A

Nucleus

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13
Q

What is a bundle of axons called? (CNS)

A

Tract

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14
Q

What is a group of cell bodies in the cerebral cortex or the spinal cord called?

A

Grey matter

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15
Q

What is a bundle of axons in the cerebral cortex or spinal cord called?

A

White matter

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16
Q

What is a group of cell bodies called in the PNS?

A

Ganglion

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17
Q

What is a bundle of axons called in the PNS?

A

Nerve

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18
Q

What is the input zone of a neuron?

A

Dendrites and cell body (receives chemical signals from other neurons)

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19
Q

What is the summation zone of a neuron?

A

Axon hillock

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20
Q

What is the conduction zone of the neuron?

A

Axon - quite long.
Carries signals from brain areas, spinal cord, or from peripheral sensory receptors.

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21
Q

What is the output zone?

A

Axon terminals
Contact with input zone of other neurons or effectors.
Release of neurotransmitters

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22
Q

What are the 4 morphological types of neurons?

A

(DRAW SLIDE 1)
Multipolar
Bipolar
Unipolar
Anaxonic

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23
Q

What is the structure of a multipolar neuron

A

Multiple processes emanate from the cell body
Lots of places where dendrites stick out of cell body

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24
Q

What is the structure of a bipolar neuron?

A

2 processes emanate from the cell body

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25
What is the structure of a unipolar neuron?
Once process emanates from the cell body. Branches into dendrite and axon
26
What is the structure of an anaxoic neuron?
No distinct axon All processes look alike
27
What are the 3 features of astrocytes?
Supply nutrients to neurons Ensheath blood capillaries Injury response
28
What is the function of a microglia (2)?
Immune cells of the CNS Engulf microorganisms and debris
29
What are the 2 function of ependymal cells?
Line fluid-filled spaces of brain and spinal cord Have cilia to circulate CSF
30
What are the 2 functions of Oligodendrocytes?
Support nerve fibres Ensheath them with myelin
31
What is the function of glia in the PNS?
Support peripheral nerve fibres Ensheath them with myelin
32
What are the 4 types of glia in the CNS?
Astrocytes Microglia Ependymal Cells Oligodendrocytes
33
What is the Schwann Cell?
Plasma membrane wrapped around an axon
34
What is a myelin sheath?
Lipid fat around an axon
35
What is the function of a myelin sheath?
Increases conduction velocity
36
What is a node of Ranvier?
Gaps between myelin Increase conduction velocity
37
What is a synapse?
Neurotransmitter release between neurons
38
What is a synaptic cleft?
When the signal is changed from electrical, to chemical, to electrical, between neurons.
39
What is a synaptic vesicle?
Little packets of neurotransmitter in presynaptic neuron
40
What is it called when information goes into the brain
Afferent (ascending)
41
What is a response that comes out of the brain called?
Efferent (descending)
42
What is the myelin sheath in the CNS made up of?
Oligodendrocytes
43
What is somatic in terms of information transmitted?
They are the stuff that we are aware of?
44
What is an example of somatic efferent?
Running
45
What is an example of somatic afferent?
Seeing
46
What is autonomic?
Involuntary
47
What is an autonomic efferent example?
Heartbeat
48
What is an autonomic afferent example?
Blood pressure
49
What is the upper motor neuron located?
Cell body in brain Axon in spinal cord
50
Where is the lower motor neuron located?
Cell body in the spinal cord Axon in the spinal nerve
51
Is the upper or lower motor neuron myelinated?
Both are myelinated
52
What is the neurotrasmitter responsible for communication between effector cells?
Ach (Acetylcholine)
53
What is the effector for the somatic efferent division?
Skeletal muscle
54
What are the 2 divisions of the autonomic efferent nervous system?
Sympathetic Parasympathetic
55
What are the effectors of the Autonomic Efferent nervous system? (4)
Smooth muscle and cardiac muscle Glands, adipose (fat)
56
Where is neuron 2 of the autonomic efferent nervous system
Cell body in brain or spinal cord Axon in PNS
57
Where is neuron 3 in the autonomic efferent nervous system?
Cell body in the PNS Axon in the PNS
58
Is neuron 2 myelinated or unmyelinated?
Myelinated
59
What neuron 3 myelinated or unmyelinated
UNmyelinated
60
Where does neuron 2 synapse?
Autonomic ganglion
61
Is neuron 2 pre- or post-ganglionic?
Pre-ganglionic neuron
62
Where does neuron 3 synapse?
Effector organ
63
Is neuron 3 pre- or post-ganglionic?
Post-ganglionic neuron
64
What is the neurotransmitter for neuron 2?
ACh
65
What is the neurotransmitter for neuron 3?
ACh or norepinephrine (NE)
66
What is the function of the sympathetic nervous system?
Prepares body for stress responses e.g. fight or flight
67
What is the function of the parasympathetic nervous system?
Prepares body for restful situations
68
What is the neurotransmitter for the sympathetic nervous system?
NE
69
What is the neurotransmitter for the parasympathetic nervous system?
ACh
70
What ganglion (para/sympathetic) has a short preganglionic axon and a long postganglionic axon?
Sympathetic
71
What ganglion (para/sympathetic) has a long preganglionic axon and a short postganglionic axon?
Parasympathetic
72
What ganglion (para/sympathetic) is close to the CNS?
Sympathetic
73
What ganglion (para/sympathetic) is far from the CNS?
Parasympathetic
74
Where are the sympathetic chain ganglia located?
On either side of the vertebral column
75
How many pairs are there in the sympathetic chain ganglia?
21-23
76
How long are the fibres of the sympathetic pathway?
Preganglionic (short) Post (long)
77
How long are the fibres of the parasympathetic pathways?
Preganglionic (long) Post (short)
78
Where is the preganglionic sympathetic pathway located?
Spinal cord (thoracolumbar)
79
Where is the postganglionic sympathetic pathway located?
Sympathetic chain
80
Where is the preganglionic parasympathetic pathway located?
Craniosacral (brainstem)
81
Where is the parasympathetic postganglionic pathway located?
In or near effector
82
How does a chemical signal get converted into an electrical signal?
A chemical signal (transmitter) opens chemically gated ion channels by binding to them, allowing Na and K to flow. If -60mV is reached, action potential will begin
83
How are chemically gated ion channels closed?
Neurotransmitter unbinds
84
How are voltage-gated ion channels opened and closed?
Membrane is depolarised causing it to open. Once membrane threshold is changed, the channel will inactivate or close
85
How are mechanically gated ion channels opened and closed?
Stretch or squish causes the membrane to deform, causing the channel to change shape. When the membrane returns to the original shape, the channel closes.
86
What are the chemically gated ion channels in a neuron?
Dendrites and cell body
87
What are the voltage gated ion channels in a neuron?
Axon hillock, axon, and axon terminals
88
What is the charge of the inside of a cell regularly?
-70mV
89
Which direction will sodium move if Na+ channels are opened?
Into the cell
90
What is a local potential?
Change in membrane potential voltage in a localised area.
91
How does a local potential occur?
Neurotransmitter binds and opens chemically-gated ion channels on dendrites/ cell body, either allowing Na in or K out.
92
What are the two forms of local potential?
Excitatory or Inhibitory
93
How does an EPSP form?
Excitatory local potentials form when a presynaptic neuron releases an excitatory neurotransmitter which opens Na gates, causing Na to enter and the cell to depolarise.
94
What causes IPSPs to form?
When a presynaptic neuron releases an inhibitory neurotransmitter, which opens K gates, causing K to leave the cell and hyperpolarise.
95
What are the two ways that local potentials can be summed?
Spatial and Temporal Summation
96
Describe spatial summation
This is the sum of the input from multiple presynaptic neurons
97
Describe temporal summation
This is the sum of the input from the repeated firing of one pre-synaptic neuron
98
Where are presynaptic inputs summed?
Axon-hillock
99
What are the steps of action potential?
1. Depolarisation of threshold 2. Rapid depolarisation due to entry of Na 3. Repolarisation due to exit of K 4. Hyperpolarisation due to exit of K 5. Return to resting membrane potential, all channels close
100
How does an electrical signal trigger a chemical signal
Na diffuses from the axon hillock to initiate a AP in the initial segment of the axon AP propagates to each neighbouring axon segment (for unmyelinated axons) or node (myelinated) in one direction AP arrives at the axon terminals causing the Ca channels to open Ca enters the terminals, causing the release of neurotransmitter in the synaptic cleft
101
What stimulates the action potential in the initial segment?
Rapid depolarisation of a flood of Na entering the axon hillock.
102
Describe AP propagation in unmyelinated axons
Membrane potential depolarises to 30mV in initial segment Na spread away from channels to bring segment 2 to threshold. This causes an action potential to develop in segment 2. The initial segment begins repolarisation. Na spreads to segment 3 and that begins to reach threshold. The action potential only can only move forward, not backward as the membrane enters absolute and refracts.
103
How fast do AP propagate along unmyelinated axons?
1-5m/s
104
Are myelinated or unmyelinated axons faster for AP conduction?
Myelinated
105
Do Nodes of Ranvier have high or low concentrations of VG channels?
High
106
Describe AP propagation in myelinated axons
AP develops in the initial segment Local current causes depolarisation which brings axolemma at node 1 to threshold AP develops at node 1 Process repeats
107
In what refractory period can a 2nd AP be generated?
Relative refractory period.
108
When does the absolute refractory period happen?
When the VG Na channels are already open or become inactive. (when depolarisation is occurring)
109
When does the relative refractory period occur?
When some Na channels begin to shift from an inactive to closed state.
110
What are the 3 key features of a chemical synapse?
Presynaptic axon terminal Synaptic cleft Postsynaptic cell
111
What happens in the presynaptic terminal during a chemical synapse?
VG ca channels on the terminal membrane Synaptic vesicles filled with neurotransmitter
112
What happens in the synaptic cleft during a chemical synapse?
A space neurotransmitter diffuses across Enzymes that inactivate neurotransmitters are present in the cleft
113
What happens in the postsynaptic cell during a chemical synapse?
There are chemically gated ion channels
114
What happens when the axon terminal is depolarised during synaptic transmission?
Ca channels open and Ca moves down the gradient into the terminal
115
What happens at the release of the neurotransmitter during synaptic transmission?
Ca interacts with vesicles which cause them to release a neurotransmitter into the synaptic cleft
116
What forms the local potentials during synaptic transmission?
Neurotransmitter binds to chemically-gated ion channels on the post-synaptic cell, causing EPSPsor IPSPs.
117
What happens at the end of the synaptic transmission?
The neurotransmitter unbinds from the chemically gated channels. Enzymes degrade the neurotransmitter and are recycled back to the axon terminal.
118
What is a key feature of the neuromuscular junction?
Specialised type of chemical synapse between axon terminal of a motor neuron and a skeletal muscle fibre
119
Is a neuromuscular junction excitatory or inhibitory?
Excitatory
120
What kind of synapse does the NMJ have?
Cholinergic
121
How many synaptic transmissions is needed to bring the muscle membrane to threshold?
1
122
How big are neuron to neuron transmission?
Tiny
123
How big are neurons to skeletal muscle synapses?
Huge
124
What kind of neurotransmitters are used in neuron to neuron transmission verus muscle transmission?
In muscle, only ACh is used, whereas in neuron to neuron, there is a variety.
125
What is the purpose of an electrical synapse?
They allow for faster depolarisation. They are rare and found in cardiac muscle.
126
What is the definition of a chemical synapse?
Presynaptic neuron releases neurontransmitter to bind to receptors on postsynaptic neuron.
127
What is definition of a neuromuscluar junction?
Specialised chemical synapse between a motor neuron and skeletal muscle.
128
What is the definition of an electrical synapse?
An electrical connection where ions flow directly from the presynaptic to postsynaptic cell through a gap junction.
129
Where does the spinal cord start?
Foramen magnum
130
Where does the spinal cord end?
Inferior border of the 1st lumbar vertebra
131
What is the sac that the spinal cord sits in made up of?
Meninges
132
Where is the spinal cavity?
Within the vertebrae, in the spinal canal
133
Where does the spinal cavity extend to?
To the coccygeal vertebrae
134
What is the meningeal sac filled with?
Cerebrospinal fluid (CSF)
135
What is the end of the spinal cord called?
Conus Medularis
136
Where does the filum terminale attach to?
Conus Medularis to the spinal cavity - end of meningeal sac
137
What is the purpose of the Filum terminal?
Anchors the spinal cord
138
How many segments does the spinal cord have?
31 pairs Cervical - 8 Thoracic - 12 Lumbar - 5 Sacral - 5 Coccygeal - 1
139
Are spinal nerves named for the vertebra they exit above or below?
Below, with the cervical nerves being an exception to this rule
140
Where does the first cervical spinal nerve exit from?
Between the skull and the first cervical vertebra
141
Draw the internal anatomy of the spinal cord
Lecture 5
142
What is white matter made of?
Axons
143
What is grey matter made of?
Cell bodies
144
What is the dorsal horn made of?
Cell bodies
145
What is the ventral horn made of?
Cell bodies
146
What is the ventral column made of?
Axon
147
What is a ganglion?
Group of cell bodies
148
What is a nerve root made of?
Axons
149
What is a dorsal root ganglion made of?
Cell bodies
150
On which side (dorsal or motor) is the sensory pathway
Dorsal
151
Where does the efferent information leave through?
Ventral roots
152
What is the front of the spinal column called?
Ventral side
153
Where is the lower motor neuron located?
In the ventral horn
154
Where are the cell bodies of the sensory neurons located?
In the dorsal root ganglion
155
Where does the output zone enter the spinal cord?
Through the dorsal roots
156
Where are the cell bodies of sensory neurons located?
In the dorsal root ganglion
157
Do dorsal nerve roots carry afferent or efferent information?
Afferent
158
Which nerve roots carry efferent information?
ventral nerve roots
159
What is a ramus?
A branch in which information flows once the nerves have left the vertebral column
160
Draw a diagram of a peripheral nerve
lecture 5 Axons covered in endoneurium These are bundled together to form a fasicle The fascicles are covered in perineurium Fascicles are bundled together to form a nerve nerves are covered in epineurium
161
What are the 3 layers of meninges on the brain?
Dura mater arachnoid Pia mater
162
What are the 5 features of dura mater?
Outermost layer Tough Inner and outer layer Space between layers forms venous sinuses Inner layer forms dural folds
163
What are the 3 features of dural folds?
Formed from inner layer of dura mater Separates major divisions (halves) of the brain Provide stability of the brain within the cranium
164
What are the 3 types of dural folds? Draw
Lecture 6 Falx Cerebri Falx Cerebelli Tentorium Cerebelli
165
What is the purpose of the falx cerebri?
Seperates the cerebral hemispheres on the median plane
166
What is the purpose of the falx cerebelli?
Seperates cerebellar hemispheres on the median plane
167
What is the purpose of the tentorium cerebelli?
Seperates the cerebrium from the cerebellum on the horizontal plane
168
What are 3 features of the venous sinus?
Located between the two layers of dura mater Collect veins Collect venous blood from the brain and old CSF.
169
What are 3 features of the arachnoid layer?
Does not extend in sulci Contains subarachnoid space and arachnoid granulations Contains blood vessels
170
What are the features of the subarachnoid space?
Filled with CSF
171
What are the features of the arachnoid granulations
Perforate the inner layer of dura mater Transport old CSF from subarachnoid space into venous sinus
172
What are 4 features of the pia mater?
Inner layer of the meninges Transparent and delicate Blood vessels in arachnoid sit on top of pia mater Adheres to brain to adhere to gyri and extend to sulci
173
What are 4 features of the ventricular system?
Network of interconnected spaces within the brain Filled with CSF (nourishes the brain) Space willed with ependymal cells CSF produced by choroid plexus
174
Draw the ventricular system
Bottom of NM 6.
175
What are 4 features of Cerebrospinal Fluid?
Produced by the choroid plexus Surrounds the CNS within the subarachnoid space Provides support and cushion Transports nutrients and waste
176
What is the circulation path of the CSF?
3rd ventricle Cerebral Aqueduct 4th Ventricle Subarachnoid space Flows around the brain and spinal cord Exits through the arachnoid granulations into venous sinus
177
Draw the external anatomy of the brain
Lecture 7
178
What does the lateral sulcus seperate?
Temporal lobe from the frontal and parietal lobes
179
What does the transverse fissure seperate?
Cerebrum from the cerebellum
180
What is associated with the front lobe?
Language, personality (bottom) Motor control (top)
181
What is the parietal lobe associated with?
Somatosensory
182
What is the occipital lobe associated with?
Vision
183
What is the temporal lobe associated with?
Memory hearing
184
Draw the internal major divisions of the brain (medially)
Lecture 7
185
What is the corpus callosum made from?
White matter
186
What are the 3 types of white matter?
Commissural Tracts projection tracts Association tracts
187
What is the purpose of commissural tracts?
Axons cross from side to side, good for co-ordination
188
What is the purpose of projection tracts?
Axons extend between cortex and other CNS areas outside cerebrum
189
What is the purpose of association tracts?
Axons on same side of cerebral cortex Communication between brain areas on the same side
190
Where is the primary motor cortex located?
Pre central gyrus
191
What primary cortexes are in the post central gyrus?
Somatatosensory and motor
192
What is the corticospinal pathway?
Upper motor neurons and their cell bodies
193
Where does the upper motor neuron synapse?
On the lower motor neuron
194
Where does the lower motor neuron synapse?
On the skeletal muscle
195
Where is the axon and cell body of the upper motor neuron?
Cell body in the primary motor cortex Axon extends into spinal cord on the opposite side
196
Where is the cell body and the axon of the lower motor neuron located?
Cell body in the ventral horn. Axon extends into the spinal cord
197
What happens when there is damage to the primary motor cortex?
Muscle weakness and paralysis on the opposite side.
198
Describe the function of neuron 1 in the dorsal/posterior column pathway
Cell body in the dorsal root ganglion Input zone in from skin Central fibre extends towards the brain Synapses onto neuron 2 in Medulla Oblongata
199
How many neurons are there between the sensory receptor and the somatosensory neuron in the postcentral gyrus (dorsal/posterior column pathway)
3
200
Describe neuron 2 in the dorsal/posterior column pathway
Cell body in medulla oblongata Axon crosses to opposite side and ascends Make synapse on neuron 3 in the thalamus
201
Describe neuron 3 in the dorsal/posterior column pathway
Cell body in the thalamus Axon ascends to the somatosensory cortex
202
What happens when there is damage to the somatosensory cortex?
No place for information to go, no perception of touch in that area
203
What is sensory transduction?
Conversion of a sensory stimulus to an action potential
204
What are the 4 types of information encoded by neural activity?
Modality Duration Intensity Location
205
What is modality?
Type of stimulus detected by a specific type of receptor
206
What are the 4 modalities of stimulus
Thermoreceptor Chemoreceptor Mechanoreceptor (tactile receptor) Mechanoreceptor (proprioceptor) Mechanoreceptor (baroreceptor) Nocieceptor
207
What is the purpose of a thermoreceptor?
detecting relative temperatures
208
What is the purpose of a chemoreceptor?
Detecting chemicals (O2, CO2) in blood
209
What is the purpose of a Mechanoreceptor - tactile
Detects light touch, pressure, and texture
210
What is the purpose of a mechanoreceptor - proprioceptor
Detects limb position in relation to the trunk, stretch in muscle, or tendon
211
What is the purpose of a mechanoreceptor - baroreceptor?
Detects pressure within the body e.g. blood vessels, airways
212
How do thermoreceptors work?
Nerve endings with temperature gated ion channels Fast adapting Channels open to let Na in to depolarise membrane, if threshold is reached, AP will be fired to brain
213
How do chemoreceptors work?
Chemically gated ion channels. Channels open, Na enters and depolarises, if threshold is reached, AP will fire to brain
214
How to mechanoreceptors work?
Mechanically-gated ion channels Physical forces distort the plasma membrane Channels open, Na depolarises membrane, if threshold is reached, then the AP will fire to the brain
215
Are tactile receptors fast or slow acting?
Fast adapting
216
Are proprioceptors fast or slow acting?
Slow acting because we don't need to know where our limbs are at all times
217
How do nociceptors work?
Can be temperature, chemically, or mechanically gated. Slow adapting and responds to extreme stimuli.
218
Is tonic or phasic a fast adapting receptor?
Phasic
219
Describe the activity of a tonic receptor?
Constantly active in the background. When stimulus arises, the AP frequency will change.
220
Describe the activity of a phasic receptor
Normally silent. Will send action potentials if there is a change but will stop quickly if it is not painful.
221
How does AP frequency change in response to a stimulus?
No AP = no sensation Some AP = some sensation More AP = more intense sensation
222
Which receptors are slow adapting?
Tonic
223
What are the 2 factors that influence sensitivity?
Size and density of receptive fields.
224
How many recepetive fields are there per neuron?
1
225
What do largely spaced receptive field provide?
Less sensitivity
226
Draw the map of neural interactions
Lecture 9
227
How is movement planned in the brain?
Prefrontal cortex will make decisions to move and plan outcome The premotor cortex will organise the movement sequences required
228
How is movement initiated?
The primary motor cortex have neurons involved in directing voluntary movement
229
What is the purpose of the basal nuclei?
Influences posture and modifies movements. Refines automatic movements by altering sensitivity of neurons by projecting into other corticospinal pathways
230
What is the purpose of the cerebellum in modifying movement?
Facilitates learning and execution of motor programs. Organises timing of muscle contractions.
231
What are the 4 pathways of movement control?
Prefrontal cortex Premotor cortex Primary motor cortex Basal nuclei and cerebellum
232
Describe the corticospinal Pathway
Upper motor neurons fire AP extending into spinal cord Activate lower motor neurons in the spinal cord which fire AP along axons within peripheral nerves Finishes in skeletal muscle
233
What is a motor unit?
Single lower motor neuron with skeletal muscle fibres
234
What is the purpose of a small motor unit?
More precise movement as there are fewer surrounding muscle fibres
235
What is the purpose of a large motor unit?
Activated any muscle fibres and provides forceful movement (of limbs)
236
Where do the signals of the left cortex control?
Right side of the body
237
Do voluntary movements have a complex or simple circuit of neurons?
Complex
238
What is the variable latency of voluntary responses?
100+ ms
239
What is the latency of reflex movements?
30-40ms
240
What are stretch receptors?
They detect muscle stretch
241
What is the structure of a muscle spindle?
Dendrite ends of nerves wrap around muscle fibres Dendritic endings have mechanically gated Na channels
242
How does a stretch reflex response happen?
Tendon tap causes contraction of muscle Muscle spindles get stretched Mechanically gated channels open the dendritic endings of the sensory neurons Depolarisation causes an AP Synaptic transmission causes depolarisation in motor neuron AP fires along the motor axon to the NMJ This stimulates a contraction, causing foot to kick.
243
How does a withdrawal reflex happen?
Nociceptors activated Sensory neuron depolarises and AP fires Sensory neuron stimulates interneurons, which stimulate motor neurons that cause flexion and inhibits those that cause extension. This makes the limb withdraw
244
What is latency?
Time delay between a stimulus and a response

HUBS 191 (7 decks)

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