Week 2-Neurophysiology Flashcards Preview

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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

desensitization

refractory state when exposure to agonist is prolonged