Human Movement and Sensation 2 Flashcards

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
Q

What is the structure of a unipolar neuron?

A

Once process emanates from the cell body.
Branches into dendrite and axon

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26
Q

What is the structure of an anaxoic neuron?

A

No distinct axon
All processes look alike

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27
Q

What are the 3 features of astrocytes?

A

Supply nutrients to neurons
Ensheath blood capillaries
Injury response

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28
Q

What is the function of a microglia (2)?

A

Immune cells of the CNS
Engulf microorganisms and debris

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29
Q

What are the 2 function of ependymal cells?

A

Line fluid-filled spaces of brain and spinal cord
Have cilia to circulate CSF

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30
Q

What are the 2 functions of Oligodendrocytes?

A

Support nerve fibres
Ensheath them with myelin

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31
Q

What is the function of glia in the PNS?

A

Support peripheral nerve fibres
Ensheath them with myelin

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32
Q

What are the 4 types of glia in the CNS?

A

Astrocytes
Microglia
Ependymal Cells
Oligodendrocytes

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33
Q

What is the Schwann Cell?

A

Plasma membrane wrapped around an axon

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34
Q

What is a myelin sheath?

A

Lipid fat around an axon

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35
Q

What is the function of a myelin sheath?

A

Increases conduction velocity

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36
Q

What is a node of Ranvier?

A

Gaps between myelin
Increase conduction velocity

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37
Q

What is a synapse?

A

Neurotransmitter release between neurons

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38
Q

What is a synaptic cleft?

A

When the signal is changed from electrical, to chemical, to electrical, between neurons.

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39
Q

What is a synaptic vesicle?

A

Little packets of neurotransmitter in presynaptic neuron

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40
Q

What is it called when information goes into the brain

A

Afferent (ascending)

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41
Q

What is a response that comes out of the brain called?

A

Efferent (descending)

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42
Q

What is the myelin sheath in the CNS made up of?

A

Oligodendrocytes

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43
Q

What is somatic in terms of information transmitted?

A

They are the stuff that we are aware of?

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44
Q

What is an example of somatic efferent?

A

Running

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45
Q

What is an example of somatic afferent?

A

Seeing

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46
Q

What is autonomic?

A

Involuntary

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47
Q

What is an autonomic efferent example?

A

Heartbeat

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48
Q

What is an autonomic afferent example?

A

Blood pressure

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49
Q

What is the upper motor neuron located?

A

Cell body in brain
Axon in spinal cord

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50
Q

Where is the lower motor neuron located?

A

Cell body in the spinal cord
Axon in the spinal nerve

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51
Q

Is the upper or lower motor neuron myelinated?

A

Both are myelinated

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52
Q

What is the neurotrasmitter responsible for communication between effector cells?

A

Ach (Acetylcholine)

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53
Q

What is the effector for the somatic efferent division?

A

Skeletal muscle

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54
Q

What are the 2 divisions of the autonomic efferent nervous system?

A

Sympathetic
Parasympathetic

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55
Q

What are the effectors of the Autonomic Efferent nervous system? (4)

A

Smooth muscle and cardiac muscle
Glands, adipose (fat)

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56
Q

Where is neuron 2 of the autonomic efferent nervous system

A

Cell body in brain or spinal cord
Axon in PNS

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57
Q

Where is neuron 3 in the autonomic efferent nervous system?

A

Cell body in the PNS
Axon in the PNS

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58
Q

Is neuron 2 myelinated or unmyelinated?

A

Myelinated

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59
Q

What neuron 3 myelinated or unmyelinated

A

UNmyelinated

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60
Q

Where does neuron 2 synapse?

A

Autonomic ganglion

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61
Q

Is neuron 2 pre- or post-ganglionic?

A

Pre-ganglionic neuron

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62
Q

Where does neuron 3 synapse?

A

Effector organ

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63
Q

Is neuron 3 pre- or post-ganglionic?

A

Post-ganglionic neuron

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64
Q

What is the neurotransmitter for neuron 2?

A

ACh

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65
Q

What is the neurotransmitter for neuron 3?

A

ACh or norepinephrine (NE)

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66
Q

What is the function of the sympathetic nervous system?

A

Prepares body for stress responses e.g. fight or flight

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67
Q

What is the function of the parasympathetic nervous system?

A

Prepares body for restful situations

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68
Q

What is the neurotransmitter for the sympathetic nervous system?

A

NE

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69
Q

What is the neurotransmitter for the parasympathetic nervous system?

A

ACh

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70
Q

What ganglion (para/sympathetic) has a short preganglionic axon and a long postganglionic axon?

A

Sympathetic

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71
Q

What ganglion (para/sympathetic) has a long preganglionic axon and a short postganglionic axon?

A

Parasympathetic

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72
Q

What ganglion (para/sympathetic) is close to the CNS?

A

Sympathetic

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73
Q

What ganglion (para/sympathetic) is far from the CNS?

A

Parasympathetic

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74
Q

Where are the sympathetic chain ganglia located?

A

On either side of the vertebral column

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75
Q

How many pairs are there in the sympathetic chain ganglia?

A

21-23

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76
Q

How long are the fibres of the sympathetic pathway?

A

Preganglionic (short)
Post (long)

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77
Q

How long are the fibres of the parasympathetic pathways?

A

Preganglionic (long)
Post (short)

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78
Q

Where is the preganglionic sympathetic pathway located?

A

Spinal cord (thoracolumbar)

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79
Q

Where is the postganglionic sympathetic pathway located?

A

Sympathetic chain

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80
Q

Where is the preganglionic parasympathetic pathway located?

A

Craniosacral (brainstem)

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81
Q

Where is the parasympathetic postganglionic pathway located?

A

In or near effector

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82
Q

How does a chemical signal get converted into an electrical signal?

A

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

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83
Q

How are chemically gated ion channels closed?

A

Neurotransmitter unbinds

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84
Q

How are voltage-gated ion channels opened and closed?

A

Membrane is depolarised causing it to open.
Once membrane threshold is changed, the channel will inactivate or close

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85
Q

How are mechanically gated ion channels opened and closed?

A

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.

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86
Q

What are the chemically gated ion channels in a neuron?

A

Dendrites and cell body

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87
Q

What are the voltage gated ion channels in a neuron?

A

Axon hillock, axon, and axon terminals

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88
Q

What is the charge of the inside of a cell regularly?

A

-70mV

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89
Q

Which direction will sodium move if Na+ channels are opened?

A

Into the cell

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90
Q

What is a local potential?

A

Change in membrane potential voltage in a localised area.

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91
Q

How does a local potential occur?

A

Neurotransmitter binds and opens chemically-gated ion channels on dendrites/ cell body, either allowing Na in or K out.

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92
Q

What are the two forms of local potential?

A

Excitatory or Inhibitory

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93
Q

How does an EPSP form?

A

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.

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94
Q

What causes IPSPs to form?

A

When a presynaptic neuron releases an inhibitory neurotransmitter, which opens K gates, causing K to leave the cell and hyperpolarise.

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95
Q

What are the two ways that local potentials can be summed?

A

Spatial and Temporal Summation

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96
Q

Describe spatial summation

A

This is the sum of the input from multiple presynaptic neurons

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97
Q

Describe temporal summation

A

This is the sum of the input from the repeated firing of one pre-synaptic neuron

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98
Q

Where are presynaptic inputs summed?

A

Axon-hillock

99
Q

What are the steps of action potential?

A
  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
Q

How does an electrical signal trigger a chemical signal

A

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
Q

What stimulates the action potential in the initial segment?

A

Rapid depolarisation of a flood of Na entering the axon hillock.

102
Q

Describe AP propagation in unmyelinated axons

A

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
Q

How fast do AP propagate along unmyelinated axons?

A

1-5m/s

104
Q

Are myelinated or unmyelinated axons faster for AP conduction?

A

Myelinated

105
Q

Do Nodes of Ranvier have high or low concentrations of VG channels?

A

High

106
Q

Describe AP propagation in myelinated axons

A

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
Q

In what refractory period can a 2nd AP be generated?

A

Relative refractory period.

108
Q

When does the absolute refractory period happen?

A

When the VG Na channels are already open or become inactive. (when depolarisation is occurring)

109
Q

When does the relative refractory period occur?

A

When some Na channels begin to shift from an inactive to closed state.

110
Q

What are the 3 key features of a chemical synapse?

A

Presynaptic axon terminal
Synaptic cleft
Postsynaptic cell

111
Q

What happens in the presynaptic terminal during a chemical synapse?

A

VG ca channels on the terminal membrane
Synaptic vesicles filled with neurotransmitter

112
Q

What happens in the synaptic cleft during a chemical synapse?

A

A space neurotransmitter diffuses across
Enzymes that inactivate neurotransmitters are present in the cleft

113
Q

What happens in the postsynaptic cell during a chemical synapse?

A

There are chemically gated ion channels

114
Q

What happens when the axon terminal is depolarised during synaptic transmission?

A

Ca channels open and Ca moves down the gradient into the terminal

115
Q

What happens at the release of the neurotransmitter during synaptic transmission?

A

Ca interacts with vesicles which cause them to release a neurotransmitter into the synaptic cleft

116
Q

What forms the local potentials during synaptic transmission?

A

Neurotransmitter binds to chemically-gated ion channels on the post-synaptic cell, causing EPSPsor IPSPs.

117
Q

What happens at the end of the synaptic transmission?

A

The neurotransmitter unbinds from the chemically gated channels.
Enzymes degrade the neurotransmitter and are recycled back to the axon terminal.

118
Q

What is a key feature of the neuromuscular junction?

A

Specialised type of chemical synapse between axon terminal of a motor neuron and a skeletal muscle fibre

119
Q

Is a neuromuscular junction excitatory or inhibitory?

A

Excitatory

120
Q

What kind of synapse does the NMJ have?

A

Cholinergic

121
Q

How many synaptic transmissions is needed to bring the muscle membrane to threshold?

A

1

122
Q

How big are neuron to neuron transmission?

A

Tiny

123
Q

How big are neurons to skeletal muscle synapses?

A

Huge

124
Q

What kind of neurotransmitters are used in neuron to neuron transmission verus muscle transmission?

A

In muscle, only ACh is used, whereas in neuron to neuron, there is a variety.

125
Q

What is the purpose of an electrical synapse?

A

They allow for faster depolarisation. They are rare and found in cardiac muscle.

126
Q

What is the definition of a chemical synapse?

A

Presynaptic neuron releases neurontransmitter to bind to receptors on postsynaptic neuron.

127
Q

What is definition of a neuromuscluar junction?

A

Specialised chemical synapse between a motor neuron and skeletal muscle.

128
Q

What is the definition of an electrical synapse?

A

An electrical connection where ions flow directly from the presynaptic to postsynaptic cell through a gap junction.

129
Q

Where does the spinal cord start?

A

Foramen magnum

130
Q

Where does the spinal cord end?

A

Inferior border of the 1st lumbar vertebra

131
Q

What is the sac that the spinal cord sits in made up of?

A

Meninges

132
Q

Where is the spinal cavity?

A

Within the vertebrae, in the spinal canal

133
Q

Where does the spinal cavity extend to?

A

To the coccygeal vertebrae

134
Q

What is the meningeal sac filled with?

A

Cerebrospinal fluid (CSF)

135
Q

What is the end of the spinal cord called?

A

Conus Medularis

136
Q

Where does the filum terminale attach to?

A

Conus Medularis to the spinal cavity - end of meningeal sac

137
Q

What is the purpose of the Filum terminal?

A

Anchors the spinal cord

138
Q

How many segments does the spinal cord have?

A

31 pairs
Cervical - 8
Thoracic - 12
Lumbar - 5
Sacral - 5
Coccygeal - 1

139
Q

Are spinal nerves named for the vertebra they exit above or below?

A

Below, with the cervical nerves being an exception to this rule

140
Q

Where does the first cervical spinal nerve exit from?

A

Between the skull and the first cervical vertebra

141
Q

Draw the internal anatomy of the spinal cord

A

Lecture 5

142
Q

What is white matter made of?

A

Axons

143
Q

What is grey matter made of?

A

Cell bodies

144
Q

What is the dorsal horn made of?

A

Cell bodies

145
Q

What is the ventral horn made of?

A

Cell bodies

146
Q

What is the ventral column made of?

A

Axon

147
Q

What is a ganglion?

A

Group of cell bodies

148
Q

What is a nerve root made of?

A

Axons

149
Q

What is a dorsal root ganglion made of?

A

Cell bodies

150
Q

On which side (dorsal or motor) is the sensory pathway

A

Dorsal

151
Q

Where does the efferent information leave through?

A

Ventral roots

152
Q

What is the front of the spinal column called?

A

Ventral side

153
Q

Where is the lower motor neuron located?

A

In the ventral horn

154
Q

Where are the cell bodies of the sensory neurons located?

A

In the dorsal root ganglion

155
Q

Where does the output zone enter the spinal cord?

A

Through the dorsal roots

156
Q

Where are the cell bodies of sensory neurons located?

A

In the dorsal root ganglion

157
Q

Do dorsal nerve roots carry afferent or efferent information?

A

Afferent

158
Q

Which nerve roots carry efferent information?

A

ventral nerve roots

159
Q

What is a ramus?

A

A branch in which information flows once the nerves have left the vertebral column

160
Q

Draw a diagram of a peripheral nerve

A

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
Q

What are the 3 layers of meninges on the brain?

A

Dura mater
arachnoid
Pia mater

162
Q

What are the 5 features of dura mater?

A

Outermost layer
Tough
Inner and outer layer
Space between layers forms venous sinuses
Inner layer forms dural folds

163
Q

What are the 3 features of dural folds?

A

Formed from inner layer of dura mater
Separates major divisions (halves) of the brain
Provide stability of the brain within the cranium

164
Q

What are the 3 types of dural folds? Draw

A

Lecture 6
Falx Cerebri
Falx Cerebelli
Tentorium Cerebelli

165
Q

What is the purpose of the falx cerebri?

A

Seperates the cerebral hemispheres on the median plane

166
Q

What is the purpose of the falx cerebelli?

A

Seperates cerebellar hemispheres on the median plane

167
Q

What is the purpose of the tentorium cerebelli?

A

Seperates the cerebrium from the cerebellum on the horizontal plane

168
Q

What are 3 features of the venous sinus?

A

Located between the two layers of dura mater
Collect veins
Collect venous blood from the brain and old CSF.

169
Q

What are 3 features of the arachnoid layer?

A

Does not extend in sulci
Contains subarachnoid space and arachnoid granulations
Contains blood vessels

170
Q

What are the features of the subarachnoid space?

A

Filled with CSF

171
Q

What are the features of the arachnoid granulations

A

Perforate the inner layer of dura mater
Transport old CSF from subarachnoid space into venous sinus

172
Q

What are 4 features of the pia mater?

A

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
Q

What are 4 features of the ventricular system?

A

Network of interconnected spaces within the brain
Filled with CSF (nourishes the brain)
Space willed with ependymal cells
CSF produced by choroid plexus

174
Q

Draw the ventricular system

A

Bottom of NM 6.

175
Q

What are 4 features of Cerebrospinal Fluid?

A

Produced by the choroid plexus
Surrounds the CNS within the subarachnoid space
Provides support and cushion
Transports nutrients and waste

176
Q

What is the circulation path of the CSF?

A

3rd ventricle
Cerebral Aqueduct
4th Ventricle
Subarachnoid space
Flows around the brain and spinal cord
Exits through the arachnoid granulations into venous sinus

177
Q

Draw the external anatomy of the brain

A

Lecture 7

178
Q

What does the lateral sulcus seperate?

A

Temporal lobe from the frontal and parietal lobes

179
Q

What does the transverse fissure seperate?

A

Cerebrum from the cerebellum

180
Q

What is associated with the front lobe?

A

Language, personality (bottom)
Motor control (top)

181
Q

What is the parietal lobe associated with?

A

Somatosensory

182
Q

What is the occipital lobe associated with?

A

Vision

183
Q

What is the temporal lobe associated with?

A

Memory
hearing

184
Q

Draw the internal major divisions of the brain (medially)

A

Lecture 7

185
Q

What is the corpus callosum made from?

A

White matter

186
Q

What are the 3 types of white matter?

A

Commissural Tracts
projection tracts
Association tracts

187
Q

What is the purpose of commissural tracts?

A

Axons cross from side to side, good for co-ordination

188
Q

What is the purpose of projection tracts?

A

Axons extend between cortex and other CNS areas outside cerebrum

189
Q

What is the purpose of association tracts?

A

Axons on same side of cerebral cortex
Communication between brain areas on the same side

190
Q

Where is the primary motor cortex located?

A

Pre central gyrus

191
Q

What primary cortexes are in the post central gyrus?

A

Somatatosensory and motor

192
Q

What is the corticospinal pathway?

A

Upper motor neurons and their cell bodies

193
Q

Where does the upper motor neuron synapse?

A

On the lower motor neuron

194
Q

Where does the lower motor neuron synapse?

A

On the skeletal muscle

195
Q

Where is the axon and cell body of the upper motor neuron?

A

Cell body in the primary motor cortex
Axon extends into spinal cord on the opposite side

196
Q

Where is the cell body and the axon of the lower motor neuron located?

A

Cell body in the ventral horn.
Axon extends into the spinal cord

197
Q

What happens when there is damage to the primary motor cortex?

A

Muscle weakness and paralysis on the opposite side.

198
Q

Describe the function of neuron 1 in the dorsal/posterior column pathway

A

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
Q

How many neurons are there between the sensory receptor and the somatosensory neuron in the postcentral gyrus (dorsal/posterior column pathway)

A

3

200
Q

Describe neuron 2 in the dorsal/posterior column pathway

A

Cell body in medulla oblongata
Axon crosses to opposite side and ascends
Make synapse on neuron 3 in the thalamus

201
Q

Describe neuron 3 in the dorsal/posterior column pathway

A

Cell body in the thalamus
Axon ascends to the somatosensory cortex

202
Q

What happens when there is damage to the somatosensory cortex?

A

No place for information to go, no perception of touch in that area

203
Q

What is sensory transduction?

A

Conversion of a sensory stimulus to an action potential

204
Q

What are the 4 types of information encoded by neural activity?

A

Modality
Duration
Intensity
Location

205
Q

What is modality?

A

Type of stimulus detected by a specific type of receptor

206
Q

What are the 4 modalities of stimulus

A

Thermoreceptor
Chemoreceptor
Mechanoreceptor (tactile receptor)
Mechanoreceptor (proprioceptor)
Mechanoreceptor (baroreceptor)
Nocieceptor

207
Q

What is the purpose of a thermoreceptor?

A

detecting relative temperatures

208
Q

What is the purpose of a chemoreceptor?

A

Detecting chemicals (O2, CO2) in blood

209
Q

What is the purpose of a Mechanoreceptor - tactile

A

Detects light touch, pressure, and texture

210
Q

What is the purpose of a mechanoreceptor - proprioceptor

A

Detects limb position in relation to the trunk, stretch in muscle, or tendon

211
Q

What is the purpose of a mechanoreceptor - baroreceptor?

A

Detects pressure within the body e.g. blood vessels, airways

212
Q

How do thermoreceptors work?

A

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
Q

How do chemoreceptors work?

A

Chemically gated ion channels.
Channels open, Na enters and depolarises, if threshold is reached, AP will fire to brain

214
Q

How to mechanoreceptors work?

A

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
Q

Are tactile receptors fast or slow acting?

A

Fast adapting

216
Q

Are proprioceptors fast or slow acting?

A

Slow acting because we don’t need to know where our limbs are at all times

217
Q

How do nociceptors work?

A

Can be temperature, chemically, or mechanically gated.
Slow adapting and responds to extreme stimuli.

218
Q

Is tonic or phasic a fast adapting receptor?

A

Phasic

219
Q

Describe the activity of a tonic receptor?

A

Constantly active in the background.
When stimulus arises, the AP frequency will change.

220
Q

Describe the activity of a phasic receptor

A

Normally silent.
Will send action potentials if there is a change but will stop quickly if it is not painful.

221
Q

How does AP frequency change in response to a stimulus?

A

No AP = no sensation
Some AP = some sensation
More AP = more intense sensation

222
Q

Which receptors are slow adapting?

A

Tonic

223
Q

What are the 2 factors that influence sensitivity?

A

Size and density of receptive fields.

224
Q

How many recepetive fields are there per neuron?

A

1

225
Q

What do largely spaced receptive field provide?

A

Less sensitivity

226
Q

Draw the map of neural interactions

A

Lecture 9

227
Q

How is movement planned in the brain?

A

Prefrontal cortex will make decisions to move and plan outcome
The premotor cortex will organise the movement sequences required

228
Q

How is movement initiated?

A

The primary motor cortex have neurons involved in directing voluntary movement

229
Q

What is the purpose of the basal nuclei?

A

Influences posture and modifies movements.
Refines automatic movements by altering sensitivity of neurons by projecting into other corticospinal pathways

230
Q

What is the purpose of the cerebellum in modifying movement?

A

Facilitates learning and execution of motor programs. Organises timing of muscle contractions.

231
Q

What are the 4 pathways of movement control?

A

Prefrontal cortex
Premotor cortex
Primary motor cortex
Basal nuclei and cerebellum

232
Q

Describe the corticospinal Pathway

A

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
Q

What is a motor unit?

A

Single lower motor neuron with skeletal muscle fibres

234
Q

What is the purpose of a small motor unit?

A

More precise movement as there are fewer surrounding muscle fibres

235
Q

What is the purpose of a large motor unit?

A

Activated any muscle fibres and provides forceful movement (of limbs)

236
Q

Where do the signals of the left cortex control?

A

Right side of the body

237
Q

Do voluntary movements have a complex or simple circuit of neurons?

A

Complex

238
Q

What is the variable latency of voluntary responses?

A

100+ ms

239
Q

What is the latency of reflex movements?

A

30-40ms

240
Q

What are stretch receptors?

A

They detect muscle stretch

241
Q

What is the structure of a muscle spindle?

A

Dendrite ends of nerves wrap around muscle fibres
Dendritic endings have mechanically gated Na channels

242
Q

How does a stretch reflex response happen?

A

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
Q

How does a withdrawal reflex happen?

A

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
Q

What is latency?

A

Time delay between a stimulus and a response