1
Q
Why is it odd that sodium does not pass through potassium channels?
A
- same charge when dissolved in water
- k+ is bigger than sodium
2
Q
How did they study the specificities of potassium channels?
A
- mutated the nucleic acids in the ion channel proteins one by one and grew them on a frog cell
3
Q
Why can Na+ not pass through potassium ion channels?
A
- in water, ions gain a hydration shell that stabilizes them and makes them bigger
- the micro-charges of the potassium channel are organized so that the potassium ion is more stable in the channel than in its hydration shell
- it will therefore leave its shell to join the channel
- BUT the Na+ ion is too small to have these ideal interactions with the carbonyle groups inside the pump. it keeps its shell and is therefore too big to enter the cell.
4
Q
What is a promoter?
A
Region of DNA that initiates transcription of a particular gene
5
Q
How does the action potential propagate?
A
- by causing a chain reaction of depolarization of the axon by puchinf positive ions always furhter toward the axon terminal
6
Q
What is particular about the types of potassium channels a human has?
A
- there are more than 40 types of potassium channels
the number of channel of each type per cell partly determines the function of the neuron
7
Q
What are glial cells?
A
lipids that surround all the cells in the brain
8
Q
What are the functions of glial cells?
A
- help traffic nutrient
- help maintain molecular stability in the extracellular space
9
Q
What is the most abundant component of the brain?
A
Glial cells
10
Q
What is the quantity proportions between glial cells and neurons in the brain?
A
between 2:1 and 5:1
11
Q
What are the three types of glial cells?
A
- Astrocytes
- Microglia
- Oligodendrocytes
12
Q
Where are the glial cells situated?
A
Exclusively in the central nervous system
13
Q
What are the roles of astrocytes?
A
- physical support
- cleans up debris in the brain and break it down
- provides scaffolding for various cellular functions
- control the chemical composition of the inter-neuronal space
- helps nourish neurons
14
Q
What is the role of microglia?
A
- responsible for the immune system of the brain that is independent from that of the rest of the body
- protect the brain from invading micro-organisms
15
Q
What are the roles of oligodendrocytes?
A
- create myelin sheath
- can myelinize 50 neurons
16
Q
What glial cell is the janitor of the cell?
A
Astrocytes
17
Q
What glial cell is responsible for the brain’s immune system?
A
Microglia
17
Q
What glial cell is responsible for myelination?
A
oligodendrocytes
18
Q
How many axons can one oligodendrocyte myelinate?
A
50
19
Q
What is the structure of the myelin sheath?
A
- the myelination is 20 microns
- the node of ranvier is 1 micron
20
Q
What is saltatory conduction?
A
21
Q
How is the action potential propagated through the axon?
A
- through saltatory conduction
22
Q
What is the impact of the presence of a sheath of lipids around the axon?
A
- no electrostatic interaction with the environment is possible, as the axon is insulated. the transport is therefore faster.
23
Q
What is the impact of the presence of nodes of ranvier in the myelin sheath?
A
- allows the regeneration of the electric charge (the charge is renewed). The transport is therefore more efficient (no loss of charge)
24
Where does the axon enter in contact with extracellular fluid?
at the node of ranvier
25
On the axon, where are the ion channels?
At the node of Ranvier
26
What is a synapse?
Junction between the axon terminal of the sending neuron and the cell membrane of the receiving neuron
27
What is decremental conduction?
- as the stimuli passes through thw axon, there is a loss of charge, so there is a decrease in the stimuli
28
What is a synaptic vesicle?
Fragments of cell membrane that contains molecules of neurotransmitters
29
How do synaptic vesicles release neurotransmitters ?
Tie themselves to the presynaptic membrane and release neurotransmitters
30
What is the space between the pre and post synaptic membrane?
synaptic cleft
31
Where are neurotransmitters released?
Synaptic cleft
32
Which type of receptor has the fastest impact on the cell's activity?
Ionotropic
33
What is the modus operandi of ionotropic receptors?
opens ion channels, either EPSP or IPSP
34
What is the main modus operandi of metabotropic receptors?
G-protein coupled receptors
Can act indirectly on ion channels through intracellular signaling cascade
35
How are vesicles released?
1) AP goes down the axon
2) VG calcium channels open
3) vesicles sense the entrance of calcium
4) the vesicles fuse with the pre-synaptic membrane
36
What are the two types of neurotransmitter receptors?
Ionotropic and metabotropic
37
What are the three types of synaptic receptors?
- postsynaptic
- presynaptic
- extrasynaptic
38
What is the purpose of a pre-synaptic neuron?
Will detect i the cell they are assoiated with is actually releasing the neurotransmitters it should be releasing
39
What is a ligand?
- signaling molecule that binds to the binding site of a receptor
40
What is a binding site?
Location on a protein receptor to which a ligand binds
41
What is an ionotropic receptor?
- receptor that is an ion channel
- the properties of its pore determine if it causes EPSPs or IPSPs
42
What is a ligand-gated ion channel?
- a receptor that is an ion channel
- known as an ionotropic receptor
- opens when the ligand binds to it
43
How does a neurotransmitter activate an ionotropic channel?
- as soon as the neurotransmitter binds itself to the recepor, it changes the shape of the receptor
44
what are the two mechanisms that keep neurotransmitter signaling in the synapse brief?
- Enzymatic deactivation
- Reuptake
45
What is enzymatic deactivation?
- Destruction of a neurotransmitter by an enzyme after action
46
What is reuptake?
Reentry of a neurotransmitter just liberated by a terminal button back through its membrane. Aided by reuptake proteins.
47
What is postsynaptic potential?
- alteration in the membrane potential of a post-synaptic neuron
48
What causes post-synaptic potential?
neurotransmitter release into the synapse that causes receptor activation
49
What are the types of post-synaptic potentials?
- excitatory
- inhibitory
50
What is the impact of an Excitatory postsynaptic potential?
Leads to depolarization, which makes the initiation of an AP easier
51
What mediates an EPSP?
Receptor proteins that open ion channels permeable to sodium
52
What is the impact of an inhibitory postsynaptic potential?
Hyperpolarization of the post-synaptic membrane, making it harder to initiate an action potential
53
What mediates an inhibitory postsynaptic potential?
Receptor proteins that open ion channels permeable to chloride ions
54
What happens whe there is an influx of sodium in the neuron, but not enough to create an Action Potential?
an increased outflow of potassium via the leack channels counteracts the change in charge
55
What are the caracteristics of a movement of ions that allow for the formation of an action potential?
sodium ions need to come in at a faster rate than potassium ions exit
56
What part of the axon must reach the threshold of excitation to trigger an action potential?
the axon hillcock
57
What is particular about the axon hillcock?
There is an important pool of sodium ions, that, when they reach the threshold of excitation, let in massive amounts of sodium ions
58
What is neural integration?
Interaction of the excitatory and inhibitory synapses on a articular neuron
59
What determines the type of postsynaptic potential?
The receptor to which the neurotransmitter binds (the cell determines how it interprets the stimuli/neurotransmitter by choosing which receptors to express)
60
To what type of ions are excitatory postsynaptic potentials associated?
Na+
61
To what type of ions are inhibitory postynaptic potentials associated?
Cl-
62
What is an interneuron?
- A neuron situated exclusively in the central nervous system
- Acts as a relay between motor neurons and sensory neurons
63
What is the role of an interneuron?
- Links sensory and motor neurons
- Allows humans to override their reflexes by using IPSPs
64
What is an inhibitory neuron?
Neuron that causes IPSPs in downstream neurons
PSYC211
flashcards
Decks in class (21)
# Cards
-
Introduction to cell biology59
-
The action potential87
-
Synaptic communication65
-
Brain anatomy159
-
Neurotransmitters131
-
Methods and streategies of research63
-
Vision147
-
The somatosensory system61
-
Taste31
-
The chemical senses30
-
Audition92
-
The vestibular system12
-
Sleep93
-
Sex112
-
Emotions57
-
Hunger and Thirst104
-
Cellular learning and memory40
-
Types of learning and memory31
-
Human communication37
-
Neurological disorders104
-
Mental illness81
