Ionic Basic of Excitation

Question 1

Ions outside of the cell

Answer 1

Na, Cl, Mg, HCO3-, Ca

Question 2

Ions within the cell

Answer 2

Proteins (-), PO3-, K+

Question 3

What are the major anions within the cell?

Answer 3

bicarbonate, phosphate, proteins, nucleic acids (cannot leave the cell)

Question 4

Simplified Nerst equation

Answer 4

E=61/z*log(out/in). Z=charge of ion

Question 5

Postive (inward) current

Answer 5

Inward movement of cations, outward movement of anions

Question 6

Negative (outward) current

Answer 6

Outward movement of cations, inward movement of anions

Question 7

What determines the Vm of a cell?

Answer 7

the equilibrium potential of the ion with the highest permeability

Question 8

What chemical blocks Na-K pump?

Answer 8

Ouabain

Question 9

What happens if the Na-k pump activity decreases?

Answer 9

Vm will depolarize

Question 10

Hyperkalemia

Answer 10

Too much K causes dyspnea, arrhythmias, palpitations, chest pain, parestesia, diarrhea

Question 11

Excitatory PostSynaptic Potential

Answer 11

Increases permeability for all cations, results in excitability

Question 12

Inhibitory PostSynaptic Potential

Answer 12

Increased permeability for Cl and K, results in decreased excitability

Question 13

Glutamate

Answer 13

Excitatory nt in CNS (EPSP)

Question 14

Metabotropic Glutamate Receptor

Answer 14

G-protein coupled. Effectors are PLC, adenylyl cyclase, ion channels. Act as autoreceptors to limit glutamate release (presynaptically)

Question 15

Ionotropic Glutamate Receptor

Answer 15

Fast excitatory synaptic responses. Increased conductances (Na, Ca, K)

Question 16

GABA

Answer 16

Major inhibitory nt in CNS (IPSP)

Question 17

Benzodiazepines/barbituates affect on GABA receptors

Answer 17

Potentiate GABA(A) response. Used as anti-seizure med

Question 18

Picrotoxin/Penicillin affect on GABA receptors

Answer 18

Blocks GABA (a) channel. Leads to seizures

Question 19

GABA (B) receptor

Answer 19

G-protein coupled. Slow response

Question 20

M-gate of voltage-gated Na channel

Answer 20

Rapid opening, Na rushes in when open. Is depolarization

Question 21

H-gate of voltage-gated Na channel

Answer 21

Slow inactivation. Na flow stops when closed

Question 22

What voltage-gated channel is delayed in opening?

Answer 22

K. Is sequential to Na influx

Question 23

Absolute Refractory Period

Answer 23

No action potential no matter how strong the stimulus

Question 24

Relative Refractory Period

Answer 24

AP only results from supra-threshold stimuli

Question 25

Passive conduction

Answer 25

Passive spread of local response. Travels short distances

Question 26

Active conduction

Answer 26

All or non response. Spreads along the entire axon

Question 27

Factors that affect AP conduction velocity

Answer 27

Axon diameter. Saltatory conduction (myelination)