Chapter 2 - Action Potentials Flashcards Preview

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Flashcards in Chapter 2 - Action Potentials Deck (27):
0

Diffusion

Particles move from high concentration to low concentration till it's evenly distributed

1

Semipermeable membranes

Let some particles through, leave others out because of physical properties

2

Ions

Electrically charged atoms and molecules

3

Ionic interactions

Like charges repel, opposites attract

4

Cations

Positive

5

Anions

Negative

6

Distribution of ions across semipermeable membrane depends on:

Relative permeability, electrical gradient, concentration gradient

7

Outside charge of cell in resting state

Positive

8

Inside charge during resting state

Negative

9

Membrane potential at resting state

-70mV

10

Depolarize

Inside becomes more positive

11

Resting ion channels

Passive channels that are unaffected by voltage

12

Voltage-gated channels

Open or closed depends on the membrane potential. Found on the AXON MEMBRANE

13

Ligand-gated channels

Open or closed depends on a specific molecule binding with receptor site on protein channel. Important in chemical transmission across the synapse

14

Phosphorylated-gated channels

Open or closed depends on phosphate group binding to the intracellular portion of a membrane protein ion channel

15

Action potential

Brief reversal of the polarity of the potential

16

All or none

Amplitude is constant in axon. It is not altered by stimulus intensity. If you reach threshold, you'll get action potential.

17

Hyper polarization

More negative on inside

18

Graded depolarizing potential

Occurs in response to stimulation. Graded bc magnitude is related to degree of stimulation. Totally dependent on degree of stimulation

19

Refractory period

Immediately after start, membrane resists start of second action potential

20

Absolute refractory period

No way action potential is being fired if other stimulus comes in right after action potential. Membrane absolutely cannot produce action potential regardless of stimulus intensity (~1min)

21

Relative refractory period

After absolute refractory period, k+ is still leaving cell, eventually cell is hyperpolarized making it more difficult to stimulate, but strong enough stimulus can produce an action potential

22

Multiple sclerosis

Demyelination of axons disrupts or prevents conduction of action potentials

23

Local anesthetics

Block voltage-gated na+ channels. Not very permanent. Low potency

24

General anesthetics

Open k+ channels wider so they resist neuron reaching threshold potential when na+ starts to enter cell. Make inside more negative, hyperpolarizing

25

Tetrodotoxin

Highly potent, blocks voltage-gated Na+ channels with very high potency. Naturally occurs in liver of pacific puffer fish

26

Why action potential is necessary?

Allows for signals to be transmitted over long distances with high fidelity and no decay. Graded potentials decay over time and space