Biol 455 Midterm 1

Front 1

What is the Nernst equation (at room temperature)?

Back 1

Eion=58/zlog[ion-out/ion-in]

Front 2

Assuming outside of cell is up, which direction is the battery when Eion<0? Eion>0?

Back 2

When Eion<0, positive end of battery faces up (because positive ions move outward). When Eion>0, the plus side faces down

Front 3

In normal neurons, which ion has a larger concentration inside than outside?

Back 3

K+

Front 4

Draw a circuit

Back 4

ok :(

Front 5

Describe the different types of recording in the patch clamp method

Back 5

Whole-cell recording: cytoplasm is continuous with pipette interior

Inside-out recording: cytoplasm domain accessible

Outside-out recording: ???

Front 6

Describe three properties of Na+ channel currents

Back 6

1) inward

2) rapid onset after depolarization

3) rapid inactivation

Front 7

Be able to do I-V curves

Back 7

ok :(

Front 8

Name and describe three classes of ion channels

Back 8

1) leak channels - conductance is constant

2) voltage-gated channels - conductance depends on voltage

3) ligand-gated channels - conductance changes upon binding of ligand

Front 9

How is outward rectification represented on an I-V curve?

Back 9

Slope is greater above x-axis than below.

Front 10

What happens during the threshold phase of an action potential?

Back 10

Once the membrane depolarizes enough (to ~-50mV), it triggers the opening of voltage-gated K+ channels

Front 11

What happens during the rising phase of an action potential?

Back 11

Sodium channel opens, Na+ flows into the cell. This drives the membrane to peak, which is near the ENa. Membrane permeability for Na increases significantly over K at this point.

Front 12

What happens during the falling phase of an action potential?

Back 12

Voltage-gated K+ channels open, start pushing membrane potential back down to Ek. Na channels start to deactivate

Front 13

What happens during the undershoot phase of an action potential?

Back 13

K+ condutance higher than at rest, membrane potential approaches Ek (which is lower than rest). As K channels close, the membrane returns to resting potential.

Front 14

[Paper] Before doing the study, what was not known?

Back 14

Capsaicin application to nociceptive sensory neurons increases membrane permeability to cations.

(i'm sure there are other stuff we didn't know but this was a clicker q)

Front 15

[Paper] What effect does VR1 expression have on HEK293 cells?

Back 15

VR1 expression is sufficient for capsaicin to elicit calcium entry into HEK293 cells.

Front 16

[Paper] VR1 shows activity in response to what?

Back 16

Heat (could explain why spicy things feel hot)

Front 17

Name each type of synapse

Back 17

Excitatory, Inhibitory, Modulatory

Front 18

What would the result of a Ca2+ channel blocker on a presynaptic terminal on the post-synaptic membrane?

Back 18

There would be no change in membrane potential as there would be no neurotransmitter released

Front 19

Which ion channel is required for an action potential?

Back 19

Sodium! Without that, no rising phase.

Front 20

If Erev=Ek, what can be said about the channels of that membrane?

Back 20

Only K-selective channels are open.

Front 21

What effect does the binding of a neurotransmitter have on a channel?

Back 21

It affects the conductance (g) of that channel.

Front 22

In what circumstance is a channel inhibitory?

Back 22

If the Erev for that channel is below threshold, then opening that channel is inhibitory, or IPSP.

Front 23

Name two excitatory neurotransmitters

Back 23

Acetylcholine and Glutamate

Front 24

Name two inhibitory neurotransmitters

Back 24

GABA and Glycine

Front 25

How does nicotine act on the nicotinic acetylcholine receptor?

Back 25

Nicotine is a partial agonist. It increases HR, BP, dizziness, etc.

Front 26

What does alpha-bungarotoxin do?

Back 26

Binds irreversibly to NAcR and prevents activation (causing paralysis)

Front 27

What is the metabotropic receptor for ACh called, and what role does it play?

Back 27

Muscarinic receptor, plays a modulatory role and is generally poorly understood

Front 28

Name and describe the two major glutamate receptor types

Back 28

AMPA: fast, ionotropic, non-selective cation channel, similar to KianateNMDA: slower, metabotropic, passes Ca2+ to cause various downstream effects, involved in memory formation

Front 29

NMDA receptor is voltage-dependent for what cation?

Back 29

Mg2+. At low Vm, current (I) approaches 0

Front 30

Identify and classify the main GABA receptors

Back 30

GABA(a) and GABA(c)- ionotropicGABA(b) - metabotropic

Front 31

How do benzos act as a sedative?

Back 31

They bind to GABA(a) receptor and potentiate (inhibitory) activity

Front 32

Which GABA receptor is a GPCR that leaks to inward rectifying K+ channels?

Back 32

GABA(b)

Front 33

How are biogenic amines packaged?

Back 33

vesicular monoamine transporters (VMAT1 and VMAT2)

Front 34

What makes endocannabinoids unique?

Back 34

They can act as a retrograde signal from postsynaptic cell to presynaptic cell.