Nerves Flashcards
1
Q
Name the two subdivions of the nervous system.
A
Central Nervous System and the peripheral nervous system.
2
Q
What are the components of the CNS?
A
Brain, spinal cord.
3
Q
What are the two subdivions of the peripheral nervous system?
A
Automonic and somatic.
4
Q
Name the three subdivisions of the automonic nervous system.
A
Sympathetic NS
Parasympathetic NS
Enteric NS.
5
Q
Name the three components of the brain stem.
A
Midbrain
Pons
Medulla Oblongata
6
Q
Name the two components of the diencephalon.
A
Hypothalamous
Thalamous.
7
Q
There are 31 spinal nerves.
How many are cervical?
A
8
8
Q
There are 31 spinal nerves.
How many are thoracic?
A
12
9
Q
There are 31 spinal nerves.
How many are lumbar?
A
5
10
Q
There are 31 spinal nerves.
How many are sacral?
A
5
11
Q
There are 31 spinal nerves.
How many are coccygeal?
A
1
12
Q
Where are spinal tracts found?
A
Spinal cord, in the white matter.
13
Q
What is found in the grey matter?
A
Cell bodies.
14
Q
What is found in the white matter?
A
Nerve fibres
15
Q
What is an afferent neuron?
A
A nerve that carries impulses toward the central nervous system.
16
Q
What is the grey matter?
A
Makes up the outermost layer of the brain and contains unmyelinated axons.
17
Q
What is the brainstem?
A
The brain stem is the lower part of the brain that’s connected to the spinal cord
18
Q
What is the gyrus?
A
The name given to the bumps ridges on the cerebral cortex (the outermost layer of the brain)
19
Q
What is a sensory neuron?
A
Nerve cells that are activated by sensory input from the environment
20
Q
What are pons?
A
A part of your brainstem, a structure that links your brain to your spinal cord.
Handles unconscious processes like breathing and sleeping.
21
Q
What is the cerebrum?
A
Largest part of the brain, divided into two hemispheres.
22
Q
What is the hypothalamus?
A
Main link between your endocrine system and your nervous system and maintains homeostasis.
23
Q
What are cranial nerves?
A
Set of 12 paired nerves in the back of your brain. Cranial nerves send electrical signals between your brain, face, neck and torso. Your cranial nerves help you taste, smell, hear and feel sensations. They also help you make facial expressions, blink your eyes and move your tongue.
24
Q
What are interneurons?
A
Nerves that transmit signals between motor and sensory neurons.
25
What are spinal nerves?
Spinal nerves are mixed nerves that interact directly with the spinal cord to modulate motor and sensory information from the body's periphery.
26
What are meninges?
Three layers of membranes which protect the brain and spinal cord
27
What is the spinal tract?
Pathway that carries information up and down the spinal cord between brain and body
28
What is the diencephalon?
Connection of the midbrain to the forebrain.
Consists of thalamus and hypothalamus.
29
What is the medulla oblongata?
The bottom-most part of your brain.
Assists with nerve signals to and from the body and and helps control breathing, blood pressure and heartbeat.
30
What is the sulcus?
A groove in the surface of the brain.
31
What is the dorsal horn?
A longitudinal subdivision of grey matter in the dorsal part of each lateral half of the spinal cord that receives terminals from some afferent fibres of the dorsal roots of the spinal nerves.
32
What is the midbrain?
The midbrain is the topmost part of the brainstem, the connection central between the brain and the spinal cord
33
What is the temporal lobe?
The temporal lobes sit behind the ears and are the second largest lobe. They are most commonly associated with processing auditory information and with the encoding of memory
34
What is the dorsal root ganglion?
The DRG is a group of cell bodies responsible for the transmission of sensory messages from receptors to the CNS
35
What is the dorsal root ganglion?
Store of sensory cell bodies
36
What is a motor neuron?
Motor neurons of the spinal cord are part of the central nervous system (CNS) and connect to muscles, glands and organs throughout the body. These neurons transmit impulses from the spinal cord to skeletal and smooth muscles (such as those in your stomach), and so directly control all of our muscle movements.
37
What is the role of the thalamus?
Regulation of consciousness and alertness.
38
What are efferent neurons?
Efferent neurons, also called motor neurons, are the nerve fibers responsible for carrying signals from the brain to the peripheral nervous system in order to initiate an action.
39
What is the occipital lobe?
The occipital lobe is the visual processing area of the brain
40
What is white matter?
White matter is found in the deeper tissues of the brain (subcortical). It contains nerve fibers (axons), which are extensions of nerve cells (neurons)
41
What is the frontal lobe?
The frontal lobes are the largest lobes in the human brain.
Most common region of traumatic brain injury.
42
What is the parietal lobe?
Either of the paired lobes of the brain at the top of the head, including areas concerned with the reception and correlation of sensory information.
43
What does the ventral horn contain?
Cell bodies of motor neurons
44
What does the soma/cell body of a neuron contain?
the nucleus
45
.What does the axon terminals of a neuron do?
Releases neurotransmitters.
46
What does the axon of a neuron do?
Sends action potential.
47
What does the initial segment (axon hillock) of a neuron do?
Triggers action potential.
48
What to the dendrites of a neuron do?
Receive information.
49
What are the three main types of neurons?
Afferent, efferent and interneurons.
50
What do astrocytes do?
Maintain external environment for the neurons and surround blood vessels to form blood brain barrier.
51
What do oligodendrocytes do?
Form myelin sheets by wrapping around axons in the CNS.
52
What do microglia do?
They are macrophages of the CNS which fight infection. (phagocytes)
53
What are ependymal cells?
Produce cerebrospinal fluid which cushions the brain.
54
What is function of the blood brain barrier?
Prevents molecules like drugs, ions and cells from entering into the brain.
Dopamine cannot cross the blood brain barrier which is why is not effective on those w alzeimhers??
55
How are oligodendrocytes and Schwann cells different in terms of the myelin sheets they form?
Shwann cells wrap around one axon while oligodendrocytes can wrap around multiple.
56
Name the three ways nerves can send electrical signals.
Active potential, graded potential, resting membrane potential.
57
What are active potentials used for?
Transmitting signals over long distances.
58
What are graded potentials used for?
Deciding when an action potential should be fired.
59
What do resting membrane potentials do?
Keep the cell ready to repsond.
60
What do resting membrane potentials do?
Keep the cell ready to respond.
61
Describe the charge of the resting membrane potential.
Inside is negative relative the the outside. q
62
What is the value for the resting membrane potential for most cells?
-70 mV.
63
If there is a balance of charges, what happens the the resting membrane potential?
There is no membrane potential.
64
What causes an electrical gradient to build up?
The leaking of K+ ions down its concentration gradient.
65
When is equilibrium reached?
When the electrical gradient is equal and opposite to the concentration gradient. Then we have a resting membrane potential.
66
State the Nerst equation.
E= RT ln [ion]o
---- -------
zF [ion]i
R=gas constant
T=absolute temp
z=valence of ion
F=faraday constant
67
The Goldman-Hodgkin-Katz eqaution is equal to...?
Three Nerst equations added together
RT ln Pk [K+]o + Pna [Na+] + Pcl [cl-]i
----- ----------------------------------------------------
F Pk[K+]i + Pna [Na+]i + Pcl [Cl-]o
68
How is the resting membrane potential generated?
The resting membrane potential is generated by the selective permeability of the resting membrane to K+
69
70
For an action potential to fire, what must the membrane potential must reach a threshold of?
-55mv.
71
Name different types of graded potentials.
Generator potentials
Postsynaptic potentials
End plate potentials
Pacemaker potentials
72
Where do generator potentials take place?
At sensory receptors.
73
Where do postsynaptic potentials take place?
Synapses
74
Where do end plate potentials take place?
Neuromuscular junction
75
Where do pacemaker potentials take place?
Pacemaker tissues
76
What do all graded potentials have in common?
They decide whether a cell is depolarised beyond threshold to fire an active potential.
77
Graded potentials are graded.
Explain this.
Basically, if there is a small action, there will be a small response.
Small stimulus=small response
Large stimulus=large response
78
In synapses, a small amount of stimulus will result in?
A small amount of neurotransmitters released will open a small number of channels and create a small postsynaptic potential.
79
Graded potentials are decremental.
What does this mean?
As they travel along the cell membrane, they become smaller.
This is caused by positive cells leaking out of the cell membrane.
80
Graded potentials are only useful...?
Over short distances.
81
How may a larger graded potential be achieved?
As one neuron has a lot of synapses, it is able to evoke it's own postsynaptic potential. If more than one neuron does this at the same time, they can add together to produce a larger graded potential.
82
How do neurons generate gradient potentials?
Manipulate different ion channels.
83
If ion channels are open, what happens to sodium ions?
Will move down it's massive conc. gradient into the cell as attracted to the negative charge of the resting potential.
84
.How could we depolarise the cell?
Close the leaky potassium cannels as potassium cannot leak out it's conc. gradient and more will stay inside the cell causing it to depolarise.
85
What is meant by EPSP?
A temporary depolarization of postsynaptic membrane caused by the flow of positively charged ions into the postsynaptic cell as a result of opening of ligand-sensitive channels.
86
What is meant by IPSP?
An inhibitory postsynaptic potentials (IPSP) is a temporary hyperpolarization of postsynaptic membrane caused by the flow of negatively charged ions into the postsynaptic cell
87
How is EPSP generated?
EPSPs generated by opening Na+/K+ channels or closing leaky K+ channels
88
How is IPSP generated?
IPSPs generated by opening Cl- channels or opening K+ channels
89
List the properties of a graded potential.
Graded, decremental, depolarising or hyperpolarising, can summate
90
What is synaptic integration?
How neurons integrate the receiving inputs from thousands of presynaptic neurons before the generation of a nerve impulse (action potential).
91
What is temporal input/summation?
The stimulation of one inpu in rapid succession.
92
Each neuron has hundreds of excitatory and inhibitory synapses
What do these evoke?
These evoke fast or slow EPSPs and fast or slow IPSPs but each one is only a few mV high
93
Each neuron has hundreds of excitatory and inhibitory synapses
What do these evoke?
These evoke fast or slow EPSPs and fast or slow IPSPs but each one is only a few mV highW
94
What does adding these postsynaptic potentials together do?
Either-
-Depolarizes it and pushes the cell to threshold and fires an action potential
-Hyperpolarises it and keeps cell way from threshold and tells it to shut up
95
When a cell goes through depolarisation after meeting threshold, what value will it peak at?
30-40mv.
96
Describe the properties of action potentials!
Think Mexican wave xoxox
1. Have a threshold-they need a graded potential to get the membrane potential up to -55mv before an action potential can be triggered.
2. All or nothing- they fire and action potential or they don't. Cannot fire half an active potential!
3. Self propagating- keeps travelling round and round.
4. Has a refractory period- stops channels opening too soon.
5. Travels slowly.
97
What is a subthreshold stimulus?
A stimulus that is too small in magnitude to produce an action potential in excitable cells.
98
What is a suprathreshold stimulus?
A stimulus that is large enough in magnitude to produce an action potential in excitable cells
99
How are action potentials activated?
(2 points).
Voltage-gated Na+ channels mediating the depolarising phase
Voltage-gated K+ channels mediating the repolarising and hyperpolarising phase
100
What is one disadvantage of self propagation?
Slow process
101
What are the two ways to speed up conduction velocity?
Use large diameter axons
Myelination
102
Why does using large diameter axons speed up conduction velocity?
Electric current flows more easily down a large axon as axial resistance is lower compared to a small axon.
It also allows sodium channels to be more spaced out along the membrane.
->Think of how water flows more easily through a drainpipe compared to a straw.
103
Which species heavily rely on large diameter axons?
Squid, earthworms and fish.
104
How does myelination (wrapping of myelin around axons) speed up conduction velocity?
Increased membrane resistance so less current leaks out of the membrane,
Decreased membrane capacitance (less current wasted charging up the membrane).
105
What are the gaps between the myelin called?
Nodes
106
Why does depolarisation spread further when myelination occurs?
Because less current is leaked out of the membrane and less current is wasted trying to charge the membrane.
107
What is saltatory conduction?
Describes how the action potential jump or 'dances' from one node to the next.
108
What are the consequences of demyelination?
Demyelinating diseases
Decreased membrane resistance (more current leaks out of the membrane).
Increased membrane capacitance (charge wasted charging the membrane).
Conduction fails.
109
Give an example of a demyelination related disease in the CNS and PNS.
CVS- multiple sclerosis (MS)
PVS- Guillian-Barre syndrome
110
Discuss some differences in terms of different axons,
-Different sizes
-Myelinated and unmyelinated
-Different classifications.
111
What generates a compound active potential?
Different types of axons conducting at different velocities.
112
Do unmyelinated axons have a faster or slower velocity compared to myelinated?
Slower
113
Describe A alpha nerve fibres.
Largest myelinated fibres.
Quickest conduction velocity.
Function is as motor neurons or proprioception.
114
Describe A beta fibres.
Large myelinated.
Sensory so detect touch and pressure.
115
Describe A gamma fibres.
Small myelinated.
Motor neurons of spindle fibres.
116
Describe A delta fibres.
Smallest unmyelinated.
Sensory and detect touch or cold.
117
Describe C fibres.
Unmyelinated.
Substantially slower than other fibres.
Sensory so thermoreceptive and detect heat or detect pain.
118
Which fibre fires action potentials the quickest?
A alpha fibres.
119
The neuromuscular junction is a type of...?
Synapse
120
Name the two types of synapses.
Chemical (majority) and electrical.
121
Where is the neuromuscular junction found?
Between a motor neuron and a skeletal muscle cell.
122
What is the first step in triggering muscle contracton?
Evoking an action potential in the skeletal muscle membrane (sarcolemma).
123
What is the presynaptic terminal filled with?
Vesicles containing ACh
124
Where is the synaptic cleft?
Gap between motor neuron and muscle cell.
125
Describe the process of muscle contraction.
11 steps good luck!! Maybe write them out a few times bestie
1. Action potential is fired in the motor neuron.
2. Depolarisation due to sodium flooding into the cell opens voltage-gated Ca channels in presynaptic terminal.
3. Fusion of vesicles.
4. Ach diffuses across the synaptic cleft.
5. ACh binds to receptors.
6. Opens ligand gated Na/K channels.
7. Evokes end plate potential.
8. Depolarises the membrane to threshold.
9. Opens voltage gated sodium channels.
10. Evokes action potential so muscle contacts.
11. ACh broken down by enzyme.
126
What is the value for the end plate potential??
-40mV >very large!
127
What do the post junctional folds means?
End plate potential has a short distance to travel to the voltage gated Na+ channels.
128
CNS synapses are very similar to...?
Neuromuscular junctions.
129
Name the one neurotransmitter acting at the neuromuscular junction.
Acetylcholine (ACh)
130
In the CNS, what are the different classes of neurotransmitter?
Amines, Amino acids (most common) peptides, purines and gases.
131
Give one example for each of the following neurotransmitters-
1. Amine
2. Amino acid
3. Peptide
4. Purine
5. Gas
1. Adrenaline, dopamine
2. GABA, glycine
3. Endorphins
4. ATP
5. Nitric oxide
132
Name the three type of arrangements of CNS synapses.
Axo-dendritic
Axo-somatic
Axo-axonal
133
What is a monosynaptic reflex?
A reflex arc that provides direct communication between sensory and motor neurons innervating the muscle
134
What is a polysynaptic reflex?
Interneurons are involved in mediating the reflex between the afferent (sensory) and efferent (motor) signals
135
What is synaptic plasticity?
The ability of synapses to change their strength.
