Flashcards in Week 2-Neurophysiology Deck (48)
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1
Types of electrical signals
1. Action potentials
2. Synaptic potentials
3. Generator potentials
2
Resting state
Membrane has electrical charge due to charges particles (ions) on either side
Inside usually about -65mV
3
Membrane potential (Vm)
Difference in electrical charge across the membrane
4
Resting membrane potential (Vr)
Membrane potential of neuron not conducting or signaling
5
Hyperpolarization
Increase in potential
-makes inside MORE NEGATIVE
6
Depolarization
Decrease in potential
Making inside MORE POSITIVE
7
Voltage
Membrane electrical potential (Vm)
8
Current
Follows flow of ions
9
Cation
Positively charged ion
10
Anion
Negatively charged ion
11
Intrinsic proteins
Attached to membrane
-can span whole bilayer or only a portion
12
Extrinsic proteins
Not attached to membrane
13
Waters of hydration
Electrostatically bound water molecules to ions
-ions carrying water-->cannot pass hydrophobic membrane
14
Gated ion channels
-Conduct ions (provide hold to cross membrane)
-select for specific ions
-open and close depending on various stimuli
15
Gated ions open/close stimuli
1. Electrical (Vm)
2. Mechanical
3. Chemical (presence of certain molecules)
16
Mechanisms for opening/closing of channels
1. One point of lumen closes
2. Lumen wall itself closes
3. Attached particularly may swing into lumen to block it
17
Ligand gated
When ligand binds, causes signal cascade
18
Phosphorylation gating
ATP phosphorylation opens channel
19
Voltage gated
Change in membrane potential opens channel
20
Pressure/stretch gating
Cytoskeleton causes channel to stretch open
21
Non-gated/passive channels
"Leaky"
-flick open randomly and continuously
-select for specific ions
-found over entire neuronal membrane
22
Ion size varies (K+ vs Na+)
Na+: smaller, with larger hydration shell
K+: larger, with smaller hydration shell
23
Selectivity filter of non-gated/passive channels
Forms weak and brief bond to ion passing through
24
Na+ passive channel mechanism
K+ simply too big to pass through
25
K+ passive channel mechanism
Na+ cannot pass through because not fully stabilized
(Na+ only binds to 2 water molecules)
-->K+ binds to 4 water molecules
26
Saturation
Flow of ions through channel causes saturation due to quick bonding in lumen
27
Channel structure
Made of at least 4 alpha helical structures
-different proteins
-copies of same proteins
-one protein complex with 4 parts
28
Kinetics of ion flow depends on...
1. Size of ion
2. Channel characteristics
3. Electrochemical force (electrostatic or concentration gradient)
4. Permeability of membrane
29
ion pumps
maintain concentration gradients
-must undergo conformational change
-must use energy (ATP) to transport against electrochemical gradient
*Active Transport
30
