1.2- CNS Cells, Cell Anatomy, & Neural Transmission Flashcards
1
Q
What is the basic building block of the nervous system?
A
Neurons
2
Q
What two ways are neurons different from other cells?
A
Excitable & Conductive
3
Q
True or False: A fetus develops more neurons after birth.
A
False. A fetus has all neurons at birth.
4
Q
True or False: Mature neurons do not divide.
A
True
5
Q
True or False: Neurons are all the same size.
A
False. Neurons can be very long or very short (axon can be up to 1 yard long).
6
Q
What is another name for cell body?
A
Soma
7
Q
What is the gooey, watery substance in the cell that contains everything else?
A
Cytoplasm
8
Q
Where is the nucleus located in healthy cells? in diseased cells?
A
The nucleus is central in healthy cells. The nucleus is displaced in diseased cells.
9
Q
What are the two types of ribosomes?
A
Free ribosomes & rough endoplasmic reticulum
10
Q
What is the function of free ribosomes?
A
to make protein for cells own use
11
Q
What is the function of rough endoplasmic reticulum?
A
produces neurotransmitters
12
Q
What part of a cell makes protein?
A
Free ribosomes
13
Q
What part of a cell produces neurotransmitters?
A
Rough ER
14
Q
What is the function of the Golgi apparatus?
A
packages neurotransmitters
15
Q
What part of a cell packages neurotransmitters made by the rough ER?
A
Golgi apparatus
16
Q
The Golgi apparatus packages neurotransmitters into a _____________.
A
synaptic vesicle
17
Q
What part of a cell is the powerhouse of the cell/releases energy?
A
Mitochondria
18
Q
What is the term for the extension of the soma that receives transmission from other cells (input site)?
A
Dendrite
19
Q
What is the function of the dendrite?
A
conducts impulse from the end of the dendrite towards the cell body
20
Q
What type of specific neuron has the most dendrites?
A
spinal motor neuron
21
Q
On average, more dendrites are found on _____ neurons.
A
motor
22
Q
On average, less dendrites are found on ____ neurons.
A
sensory
23
Q
What is an output unit of the cell that sends impulses to the next target cell?
A
Axon
24
Q
How many axons on a neuron?
A
one, but it can go very long distances
25
Where can an axon impulse go? (3 things)
to other neurons, muscle cells, or glands
26
What is the narrowed area of the cell body that forms into the axon?
Axon hillock
27
What is the broadened end area of the axon just before the synapse?
Presynaptic terminal
28
What helps with the flow of material to and from cell body and presynaptic terminal?
Microtubules
29
What are the two transport methods along the microtubules?
Anterograde transport and retrograde transport
30
What type of transport is the flow of material AWAY from the cell body TOWARD end of axon?
Anterograde transport
31
What type of transport is the flow of material from the end of the axon back towards the cell body?
Retrograde transport
32
Synaptic vesicles return via ________ from the synapse after release of the _______ for reuse.
retrograde transport; neurotransmitter
33
What type of transport slows with the aging process?
Axoplasmic (process of anterograde & retrograde transports together)
34
What is the term for the gap between neurons?
synaptic cleft
35
Where is the site for interneural communication?
synaptic cleft
36
The synapse includes the ________, _________, and the ________.
pre-synaptic membrane, synaptic cleft, and the post-synaptic membrane
37
Where does the chemical process of transmission occur?
synapse
38
Where is a synapse located?
It can be located anywhere on a dendrite, cell body, or axon.
39
Some areas of a synapse are more excitable than others. What is the more excitable area?
Dendrite -> takes less neurotransmitters
40
How are neurons classified?
1. Number and arrangement of parts
| 2. Function
41
What type of neuron has many dendrites from the cell body with only 1 axon?
Multipolar neuron
42
What is the most common cells of the nervous system?
multipolar neurons
43
What type of neuron receives huge amounts of input from multiple places?
multipolar neurons
44
What type of neuron travels from the CNS to the muscle?
Efferent (motor) neurons
45
What is an example of an efferent neuron?
spinal motor neuron
46
What is the traveling path of an efferent (motor) neuron?
from the CNS to muscle
47
What type of neuron has 2 primary processes from soma- the dendrite and axon?
bipolar neuron
48
What type of neuron might have a dendrite root that divides into multiple dendritic branches?
bipolar neuron
49
What type of neuron has high precision in reception and transmission?
bipolar neuron
50
Why does a bipolar neuron have high precision in reception and transmission?
because 1 single dendrite receives info and transmits to only 1 other neuron
51
What type of neuron is a bipolar neuron where dendrite receives impulse in a sensory organ and transmits back towards the CNS?
Afferent (sensory) neuron
52
Afferent (sensory) neuron- bipolar neuron where _____ receives impulse in a sensory organ and transmits ______________
dendrite; back towards the CNS
53
Examples of afferent (sensory) neurons
retina, inner ear, taste buds
54
What is a subclass of bipolar cells?
Pseudounipolar
55
What type of neuron appears to have a single projection from the cell body that divides into 2 axonal roots (no true dendrites)?
pseudounipolar
56
What are the 2 types of axonal roots of a pseudounipolar neuron?
1. Peripheral axon
| 2. Central axon
57
What is long and myelinated, conducts sensory info from the sensory organs to the cell body?
Peripheral axon
58
What conducts info from soma to spinal cord?
Central axon
59
What is the travel path of a peripheral axon?
from the sensory organs to the cell body
60
What is the travel path of a central axon?
from soma to spinal cord
61
Why does a pseudounipolar neuron travel quickly?
it skips the soma
62
___________ neurons - CNS to smooth or skeletal muscles
Efferent (motor)
63
__________ neurons - sensory info from periphery to CNS
Afferent (sensory)
64
__________ - process info locally or sends info short distances from one area of the nervous system to another (processes info at the spinal cord level)
Interneurons
65
Which direction do efferent neurons travel?
from CNS to smooth or skeletal muscles
66
Which direction do afferent neurons travel?
from periphery to CNS
67
What type of support cell provides support for neurons and help with neural transmission?
Glial cells
68
What type of cell may play a role in Alzheimer's disease and MS?
Glial cells
69
Glial cells are classified into what two sizes?
Microglia and macroglia
70
What type of cell acts as phagocytes?
Microglia
71
Microglia cells are only found in the _____.
CNS
72
What do microglia cells do?
Act as phagocytes- destroy bacteria and old or damaged cells
73
What are the three types of macroglia cells?
1. Astrocytes
2. Oligodendrocytes
3. Schwann cells
74
_______ are star shaped cells found in CNS.
Astrocytes
75
Where are astrocytes found?
CNS
76
What 3 things do astrocytes do?
1. role in cell communication
2. act as scavengers to clean up debris (remove spent neurotransmitter)
3. transport nutrients to nerve by connecting neuron to capillaries (part of blood-brain barrier)
77
What type of cell has a role in cell communication (stimulated by other neurons, change in shape or pressure)?
Astrocytes
78
What type of cell acts as a scavenger to clean up debris (remove spent neurotransmitter)?
Astrocytes
79
What type of cell transports nutrients to nerve by connecting neuron to capillaries?
Astrocytes
80
Problems with astrocytes can lead to _______.
scarring in brain causing tumors and seizures
81
What type of cell produces myelin in CNS?
Oligodendrocytes
82
What is the lipid and protein layer that wraps around axon?
Myelin
83
What insulates electrical conduction so one fiber does not short out on another?
Myelin
84
More and thicker myelin = __________
faster conduction
85
Not continuous, areas not myelinated called ______
Nodes of Ranvier
86
Diseases (MS) can attack ______.
myelin
87
What is myelin?
a lipid and protein layer that wraps around axon and insulates electrical conduction so one fiber does not short out on another
88
What is the function of a oligodendrocyte?
to produce myelin in CNS
89
What type of cell produces myelin in the PNS?
Schwann cells
90
Schwann cells are the only support cells of the PNS. It must do what three things?
1. make myelin
2. clear debris
3. support neurons
91
Each Schwann cell may myelinate ______ axons.
several
92
What is the outer plasma membrane of the Schwann cell called?
Neurolemma
93
What is Neurolemma?
the outer plasma membrane of the Schwann cell- covers the myelin produced around the axon in the PNS
94
True of False: Neurolemma degenerates when cut.
False. Does NOT degenerate when cut.
| (why nerve can regenerate in PNS -> can remake connections) *will degenerate in CNS
95
What happens if a soma is damaged?
the entire nerve cell dies
96
Wallerian degeneration occurs when ___________.
axon is damaged
97
What 4 things occur during Wallerian degeneration?
1. damaged segments retract away from each other
2. distal axonal segment degenerates & pulls away from myelin sheath
3. axon terminal degenerates & dies
4. glial cells scavenge the area
98
What is axonal sprouting?
if soma of injured cell is intact, regeneration of PERIPHERAL nerves is possible
99
How can an injured axon regrow to a new target?
1. when axon degenerates, it leaves before the neurolemma (like a hollow pipe)
2. this pipe can act as a guide for axonal regrowth to direct it back to the proper target
100
Where is neurolemma produced?
PNS (one of the reasons regeneration does not occur in the CNS)
101
What is neuroma?
nerve tumor of free nerve ending
102
How does a neuroma occur?
when a nerve tries to regenerate and can't find its way
103
What is the growth rate of an axon?
1mm/day
104
True or False: An axon returns to a pre-injury state.
False. Not complete or same as before injury.
105
Why might an axon not be the same as before injury?
1. may go to wrong target
| 2. schwann cells remake myelin but have more nodes (slows conduction)
106
Neurons function because of a difference in _____ _____ across the membrane created by having different _____ ______ on either side of the cell membrane.
electrical potential
electrical charges
107
How is the difference in electrical potential created?
by having ions with different electrical charges on each side of the membrane
108
There are 4 channels that allow ions to move back and forth across the cell membrane of the axon. One is a non-gated channel. What are the 3 gated channels?
1. modality gated
2. ligand gated
3. voltage gated
109
What type of channel allows slow diffusion of a small number of ions via osmosis through the membrane?
non-gated channels (open all the time & allows constant dripping)
110
Describe Modality gated channels
- open in response to touch, pressure, hot, cold, etc
| - only in sensory system
111
Describe Ligand gated channels
- open in response to neurotransmitter binding
| - in post synaptic membrane
112
Describe Voltage gated channels
- open in response to changes in electrical potential across the membrane
- as one channel depolarizes it opens up the next channel
113
What type of gated channel opens in response to touch, pressure, hot, cold?
Modality gated
114
What type of gated channel opens in response to neurotransmitter binding?
Ligand gated
115
What type of gated response opens in response to changes in electrical potential across the membrane?
Voltage gated
116
What type of gated channel is only in sensory system?
Modality gated
117
What type of gated channel is in post synaptic membrane?
Ligand gated
118
What type of gated channel opens as the previous one depolarizes?
Voltage gated
119
Resting potential is _____mV.
| Action potential is ______mV.
Resting potential is -70mV.
| Action potential is +35mV.
120
What occurs when the axon has a negative ionic charge inside due to large negative molecules permanently trapped in the cell; outside there is a positive ionic charge due to Na+ ions?
Resting potential
121
Resting potential-
| What type of charge is inside the cell? Outside the cell?
Inside the cell is a negative charge. Outside the cell is a positive charge.
122
With impulse transmission, when a stimulus is received, a ____________ of the cell membrane occurs.
reversal or depolarization
123
How does a reversal or depolarization of a cell membrane occur?
1. started by opening of modality or ligand gated channels allowing Na+ (sodium) in the cell
2. as Na+ enters, charge inside that area of the membrane rises to +35mV
124
What is it called when the adjacent membrane reaches the +35mV threshold and the next voltage regulated channel down the membrane opens?
Action Potential
*once tripped, the succession continues the entire length of the neuron
125
What happens when the impulse reaches the presynaptic membrane?
the synaptic vesicles containing the neurotransmitter flattens against the membrane emptying the neurotransmitter into the synaptic cleft
126
__________ - if axon is myelinated this process occurs much faster because depolarization will only have to occur where there is no myelin (Node of Ranvier)
Saltatory Conduction
127
What must happen after depolarization?
cell must return back to the resting potential
128
After depolarization occurs, cell must return back to resting potential. Another gate opens allowing __________.
K+ (potassium) to leave the cell.
129
After depolarization occurs, the cell must return back to the resting potential. Another gate opens allowing K+ to leave the cell. Then what happens?
the negative charge is restored, but actually becomes more negative, down to -135mV
(also a problem b/c Na+ is inside the membrane and K+ is outside)
130
What is the refractory period?
time between depolarization and restoration of the -70mV resting potential
131
What are the two types of refractory periods?
1. Absolute refractory period
| 2. Relative refractory period
132
__________ - membrane is completely unresponsive to another stimuli (occurs during the time the membrane has a positive charge)
Absolute refractory period
133
___________ - occurs while restoration of the - charge is occurring (internal charge is more negative than the -70mV resting potential)
Relative refractory period
134
What type of refractory period occurs during the time the membrane has a positive charge?
Absolute
135
What type of refractory period occurs during the restoration of the - charge?
Relative
136
What type of refractory period may be responsive to a very strong stimuli?
Relative refractory period
137
What occurs via an active transport system that restores the resting potential?
Repolarization
138
What is the Sodium Potassium Pump?
the cell membrane uses energy (ATP) to actively eject Na+ while returning K+ into the cell
139
_________ - the cell membrane uses energy (ATP) to actively eject Na+ while returning K+ into the cell
Sodium Potassium Pump
140
What is a Node of Ranvier?
an area of no myelin
