Exam 2

Question 1

What does a voltage clamp measure?

Answer 1

Current responses to different voltages

Question 2

Explain the concept of a voltage clamp.

Answer 2

In a voltage clamp setup, there is a specific voltage that the cell membrane is set to run continuously. Changes in voltage can be set as step voltages. This method is important mostly because we can see how ions react with the cell membrane under different voltages.

Question 3

How do graphs of leak channels and voltage-gated channels differ?

Answer 3

Leak channels are a straight line and are always “active” whereas voltage-gated channels have a curve and have a “start”

Question 4

How do you know Voltage-gated channels have reached maximum conductance?

Answer 4

The line on the graph becomes linear

Question 5

What is a G-V plot and what does it look like?

Answer 5

It graphs Voltage (X) with Conductance(Y) and it’s a sigmoidal curve

Question 6

What is an I-V plot and what does it look like for K (v) channels?

Answer 6

It graphs Voltage (X) with Current(Y) and it’s a curve with an upward slope

Question 7

How many subunits do Kv channels have? How many subunits do Leak K channels have?

Answer 7

4 and 2

Question 8

What does an I-V plot for Na (v) look like?

Answer 8

Looks like a big U

Question 9

How would increased inactivation of Na channels affect a graph? What can cause this increased inactivation?

Answer 9

The Na would have a bigger and shorter spike compared to when there are smaller amounts of Na inactivation. Higher Vm can cause more Na inactivation

Question 10

What is the patch clamp method?

Answer 10

The patch clamp technique records the electrical currents flowing through individual ion channels or across the entire cell membrane of a single cell. (>10 Picoamps for one channel, 1 Picoamp- 10 Nanoamps for whole cell)

Question 11

What are the different subsections of the patch clamp method?

Answer 11

Whole-cell recording: Measures total current across the entire membrane
Inside Out & Outside Out: Isolates membrane sections for study of ion channels in a controlled environment
Single-channel recording: Allows for the recording of current through a single ion channel.

Question 12

What is each subsection of the patch clamp method good for?

Answer 12

Whole-cell recording: This allows the recording of currents from the entire cell, giving access to all the ion channels.
Inside-out mode: Useful for testing how intracellular conditions affect the ion channels.
Outside-out mode: Useful for testing how extracellular conditions affect the ion channels.

Question 13

What is the intracellular recording method?

Answer 13

A microelectrode is inserted into the cell, allowing direct measurement of the cell’s electrical activity. (1-100mV)

Question 14

What is the extracellular recording method?

Answer 14

Records electrical activity outside of the cell (10 microvolts-1 mV)

Question 15

What is an EEG?

Answer 15

Measures voltage fluctuations caused by the synchronized activity of large populations of neurons. (10-100 microvolts)

Question 16

What are Piezo Channels?

Answer 16

They are huge channels that sense force on membrane

Question 17

What is the difference between chemical synapses and electrical synapses?

Answer 17

Electrical synapses are connected by gap junctions and transmit electrical signals
Chemical synapses have a synaptic cleft in which neurotransmitters are released

Question 18

What is the active site for neurons?

Answer 18

Its the place where neurotransmitters are released

Question 19

What does postsynaptic density refer to?

Answer 19

It refers to the area on the receiving neuron where receptors are clustered

Question 20

What roles do GABA and Glutamate play when it comes to neurons?

Answer 20

Glutamate is the most common excitatory neurotransmitter
GABA is the most common Inhibitory neurotransmitter

Question 21

What do neural transporters do?

Answer 21

They help move neurotransmitters back into neurons after they’ve been used in signaling. (Neurotransmitters are recycled)

Question 22

What are G-Protein-coupled Receptors?

Answer 22

These are a type of receptor that, when activated by a neurotransmitter, cause changes inside the cell through a protein called a G-protein. (This leads to slower but longer-lasting effects)

Question 23

What are the 2 two types of PSP (Postsynaptic potential) and what do they do?

Answer 23

EPSP: An EPSP is a change in the electrical charge of a neuron that makes it more likely to fire a signal.
IPSP: An IPSP is a change in the electrical charge of a neuron that makes it less likely to fire a signal.

Question 24

What are Autoreceptors?

Answer 24

Autoreceptors are receptors on the sending neuron that detect when enough neurotransmitter has been released. (They help regulate things)

Question 25

What is the difference between agonists and antagonists?

Answer 25

Antagonists prevent neurotransmitter binding
Agonists mimic neurotransmitters

Question 26

What is a Miniature Postsynaptic Potential?

Answer 26

It’s a small change in a neuron’s electrical charge caused by the release of neurotransmitters, even without a full signal.

Question 27

What is spatial summation?

Answer 27

Signals from multiple synapses are added together (Multiple synapses, multiple signals)

Question 28

What is temporal summation?

Answer 28

Multiple signals from the same synapse arrive in quick succession. (One synapse, multiple signals) (More likely to fire a signal)

Question 29

What is the difference between AMPA and NMDA receptors?

Answer 29

AMPA receptors are responsible for most of the fast, initial EPSCs.
NMDA receptors contribute to the slower, sustained phase of EPSCs, particularly in conditions of strong depolarization or low Mg²⁺ levels. (NMDA receptors allow calcium in)

Question 30

What is the overall pathway for both LTP and LTD?

Answer 30

LTP: Strong stimulation → large Ca²⁺ influx → activation of protein kinases → more AMPA receptors → stronger synapse.
LTD: Weak stimulation → small Ca²⁺ influx → activation of protein phosphatases → removal of AMPA receptors → weaker synapse.

Question 31

What do snare proteins do?

Answer 31

They help bring the vesicles and cell membrane closer to each other when it is time for neurotransmitter release