Chapter 2 Flashcards
1
Q
The Central Nervous System (CNS) consists of…
A
The brain and spinal cord
2
Q
The Peripheral Nervous System (PNS) consists of…
A
Everything else outside the brain and spinal cord (peripheral=perimeter)
3
Q
Bundles of axons in the PNS
A
Nerves
4
Q
Bundles of axons in the CNS
A
Tracts
5
Q
Sensory neurons…
A
Allow us to process stimuli and take it in
ex. visual stimulation
6
Q
Motor neurons…
A
Allow us to use our muscles
i.e. brain signals our muscles to function and contract
7
Q
Interneuron
A
Allows neurons to communicate with other neurons, acts as a middleman for sensory and motor neurons
8
Q
What is retrograde axoplasmic transport?
A
From the axon towards the cell body
slower process
9
Q
What is anterograde axoplasmic transport?
A
From the cell body towards axons
really fast process
10
Q
What is one of the most important functions of the soma?
A
To maintain metabolic functions
11
Q
Why are the cell membranes important?
A
They control access to the inside of the cell
12
Q
What is a phospholipid bilayer?
A
A bilayer (two layers) of phospholipids arranged facing each other to create a cell membrane
13
Q
What is the function of cytoskeletons?
A
Allows the cell to keep its structure
14
Q
Glial cells in the CNS…
Glia means glue
A
are the most important type of supporting cell (CNS)
15
Q
The 3 types of glial cells
A
- Astrocytes
- Oligodendrocytes
- Microglia
16
Q
The 4 functions of Astrocytes
means “star cells”
type of support cell/ glial cell (CNS)
A
- Provide necessary chemicals to neurons
- Transport nutrients from capillaries to neurons
- Provide physcial support to neurons
- Clean up debris in the brain
17
Q
What is phagocytosis?
phago=eat, cyto=cells
A
The process of cleaning up cellular debris, performed by astrocytes
18
Q
How does phagocytosis work?
A
The plasma membrane surrounds debris and encloses it in a vacuole to be broken down
19
Q
What can happen if the phagocytosis process is abnormal?
A
Alzheimer’s; it’s important that there isn’t too many or too few phagocytosis cycles
20
Q
What are Oligodendrocytes?
oligo=a few, dendro=branch, cyt=cells
type of support cell/glial cell (CNS)
A
Cells with just a few branches; they form myelinated sheaths
important for information
21
Q
What is a process (in cell terms)?
A
Anything that extends from a cell
22
Q
What are Microglia
smallest among glial cells
A
Aide in cleaning up cellular debris; serve as a protective system against invading microogranisms. Fully responsible for the inflammatory response following brain trauma
23
Q
The glial cells in the PNS
also supporting cells
A
Schwann cells
24
Q
What are Schwann cells?
A
Similar to oligodendrocytes; wrap around axons of neurons to form mylon sheath for insulation
25
How are Schwann cells different from oligodendrocytes (in terms of location)?
1. Schwann cells are in the PNS (outside brain and spinal cord) and oligodendrocytes are in the CNS (brain and spinal cord)
26
How are Schwann cells different from oligodendrocytes (in terms of functionality)?
Oligodendrocytes extend processes over axons with cell body separated, Schwann cells wrap the entire cell body and processes over axons and continue to spiral around it (think lollipop)
27
How are Schwann cells different from oligodendrocytes?
| Think multitasking; how efficient the cells are
A single oligodendrocyte can myelinate many axons in the CNS; one Schwann cell never myelinates more than one axon in the PNS
28
How are Schwann cells in the PNS similar to axolotyls?
Axolotyls can regrow severed limbs; Schwann cells can help damaged nerves to regrow or heal to restore function
| NOT THE SAME FUNCTION; SIMILAR CONCEPTS
## Footnote
This is difficult because there are no Schwann cells in the CNS to help restore function in the brain/spinal cord
29
How are the chemical properties of the glial cells in the CNS different from the glial cells in the PNS?
Different things influence them to function; some cells are exclusively attacked because of their properties while other cells are spared
30
What is the blood-brain barrier?
A barrier between the PNS and the CNS that prevents certain substances from being transported through each nervous system
## Footnote
think blue dye injected in to bloodstream; all organs turned blue except for brain and spinal cord
31
How are capillaries different between the brain and the rest of the body?
Capillaries throughout the body have gaps to optimize bloodflow; capillaries in the brain have closed gaps so that only certain substances can pass through
32
Is the blood-brain barrier permeable or semipermeable?
Semipermeable; only certain things can pass through
33
What is the Area postrema?
The blood-brain barrier is weaker in this part of the brain; monitors the blood for toxic substances and forces you to throw up if anything is found
34
Neurons send/receive messages from:
Other neurons, voluntary/involuntary muscles, internal and sense organs, glands
35
What is withdrawal reflex?
Reflex from interacting with noxial stimuli (dangerous stimuli) that makes our body retract itself from harm without our thinking
36
What is action potiential?
Rise and falls in electrical potential across the membrane of the axon that travels down the axon like a wave
37
What is a neuron's electrical potential when it's at rest?
-70 mV (milivolts) because the inside of the neuron is more negatively charged than the outside of the neuron
## Footnote
around 5% of the voltage of a AA battery
38
How does an electrical potential occur?
A difference in charges between two points
39
What are ways that resting potential is maintained
Diffusion, electrostatic pressure, composition of intracellular and extracellular fluid, the sodium-potassium pump
40
What is diffusion?
Molecules going from areas of high conentration to low concentration when there are no forces/barriers in the way
41
What is electrostatic pressure?
Opposites attract; likes repel
42
Fluid INSIDE our neurons is called...
INTRAcellular fluid
## Footnote
ex: cytoplasm
43
Fluid OUTSIDE our neurons is called...
EXTRAcellular fluid
44
What is the sodium-potassium pump?
A specialized pump in the membrane that fights the forces of diffusion and electrostatic pressure that want to push sodium ions in our neurons
45
What is the structure of the sodium-potassium pump?
Cylindrical and made up of proteins; has 2 tubes. One tube pumps 2 potassium ions into the cell, the other tube pumps 3 sodium ions out of the cell
46
How much energy does the sodium-potassium pump take to function?
About 40% of the neurons metabolic recources and is continuously running
47
What is depolarization?
When the charge of the inside of a cell becomes less negative (more positive) than the outside of the cell
48
What is an ion channel
Embedded in the cell membrane; a tube that transports ions (secific kinds of ions) through the membrane
## Footnote
the channel can close so no ions can pass through
48
Which ion channels are involved in the action potential?
Sodium (Na) and Potassium (K)
49
What does "voltage-dependent" mean?
| in reference to ion channels
Channels know whether to open or close when they get to a certain electrical potential across the membrane
49
Which ion channels are voltage-dependent?
Sodium (Na) and Potassium (K)
49
What is the first step in action potential?
Sodium ion channels open (threshold of excitation) and depolarization occurs
50
What is the second step in action potential?
| think the line going up
K+ channels open, K+ leaves the cell
51
What is the third step of action potential?
Na+ channels change and Na+ no longer enters the cell (action potential is at its peak)
52
What is the fourth step of action potential?
K+ continues to leave the cell, and membrane potential goes back to resting level
53
What is the fifth step of action potential?
K+ channels close and Na+ channels reset
54
What happens when action potential is at its peak?
Na+ channels become refractory and no more Na+ can enter the cell
55
What does refractory mean?
To close; close until the ions reverts back to the resting potential/level
56
What is the sixth (and final) step of action potential?
Extra K+ diffuses outside of the cell
57
What is the All-or-none law?
AP either does or does not occur; if it does, it transports all the way down to the end of the axon and the AP size/shape does not relate to the intensity of the stimulus
58
What is the Rate Law?
Faster rates of AP indicate larger stimuli while slower rates of AP indicate smaller stimuli
| kind of like a dimmer light switch
59
How does AP occur through an UNMYELINATED axon?
The action potential propagates down the length of the axon like “the wave” at a football game
60
How does AP occur through a MYELINATED axon?
The action potential conducts passively until it reaches the node of ranvier
61
What happens when the AP reaches the node of ranvier?
AP is regenerated through the small gaps of (node of ranvier) and makes the AP process faster
62
What is the node of ranvier?
A gap where you can see the bare axon in between the coverings of mylen
63
Do myelinated or unmyelinated axons conduct AP faster?
Myelinated axons conduct AP faster
64
What are synapses?
Spots where the processes of neurons connect to other processes of nueurons
65
What are terminal buttons?
The end of a synapse; usually only one end
66
What are axodendritic synapses?
Synapses that involve axons and dendrites making contact
67
68
What are axoaxonic synapses
Synapses that involve connections between two axons
69
What are pre-synaptic neurons?
The neuron sending the message down the axon
70
What are post-synaptic neurons?
The neuron receiving the message at the dendrites
71
What is a synaptic vesicle?
Sacs that contain neurotransmitters, transported all the way down the cell body
72
What ion starts the process of the neurotransmitter vesicles being dumped into the synapse?
Calcium ions rush into the cell
73
What heppen because of the influx of calcium ions in the cell?
Vesicles merge with the cell membrane and start dumping their contents (neurostransmitters)
74
What happens when vesicles dump their neurotransmitters?
They get recycled so they can be used again
75
What are postsynaptic receptors?
Special protein molecules located inside the postsynaptic membrane
76
What is special about the way postsynaptic receptors function?
| "lock and key"
They have special regions where only certain neurotransmitters can be binded
77
What are ligands?
Molecules that fit into binding sites
## Footnote
ex: neurotransmitters
78
What does "receptor activation" mean/entail?
The receptor opens neuro dependent ion channels that allow certain ions to pass through the cell
79
What does a neuro-dependent ion channel mean?
They only open when the right neurotransmitter gets attached to the binding site
80
What are ionotropic receptors?
They open ion channels directly
81
What are metabotropic receptors?
Ion channels are opened indirectly through a chemical chain
| metabolic= requires energy
82
What happens during the metabotropic receptor process?
Neurotransmitter binds to metabotropic receptor and activates the G protein, the G protein activates an enzyme that will stimulate the "second messenger" chemical (and synthesize); then it will diffuse through cytoplasm to ion channel, attach to ion channel and opens channel
83
Which approach to opening receptors is faster?
The direct method; ionotropic receptors
84
Which approach to opening receptors has a longer lasting effect?
The indirect method; the metabotropic receptors
| 2nd messenger lasts longer after dispersion
85
What polarization process is associated with an excitatory PSP?
Depolarization
86
Which neurotransmitter-dependent ion channels causes an excitatory postsynaptic potential?
Sodium ions (Na+) and Calcium ions (Ca2+)
87
Which neurotransmitter-dependent ion channels causes an inhibitory postsynaptic potential?
Potassium ions (K+) and Chloride ions (Cl-)
88
Which polarization process is associated with an inhibitory PSP?
Hyperpolarization
89
What's the difference between AP and PSP processes?
AP occurs on the presynaptic axon and involves depolarization then hyperpolarization and ALL OR NONE; PSP occurs on the postsynaptic dendrites and involves EITHER depolar (EPSP) OR hyperpolar (IPSP) and GRADED
90
What does "graded" PSPs mean?
The potentials of postsynaptic cells are distinguished as big or small, unlike APs that are all or nothing
91
What does reuptake mean?
Terminal buttons of presynaptic neurons have special transporter molecules that force neurotransmitters back into the cell to be reused later
92
What is enymatic deactivation?
93
What are the ways to terminate/regulate PSPs?
Reuptake and enzymatic deactivation, autoreceptors, axoaxonic synapses, glial cells
94
What are autoreceptors?
On the presynaptic neuron, neurotransmitters automatically bind to these receptors on the cell; there are no ion channels because they are metabotropic
95
What is neural integration
96
A neuron will only fire an action potential if the postsynaptic potentials are larger than...
The threshold of excitation
97
What is temporal summation?
98
99
