patch clamp

Question 1

What are the electrical signals generated by neurons called?

Answer 1

Changes in Vm

Vm stands for membrane potential.

Question 2

How do neurons generate electrical signals?

Answer 2

By rapid changes in permeabilities to specific ions through opening and closing of ion channels

Usually, these channels are voltage-gated.

Question 3

What is required for neuronal signaling?

Answer 3

Establishment and maintenance of concentration gradients across the membrane via active transporters

This creates electrochemical gradients.

Question 4

What is a Leakage Channel?

Answer 4

Ion channel that is always open

Question 5

What initiates the opening of a Voltage Gated Channel?

Answer 5

Change in the membrane voltage (membrane potential)

Question 6

What causes a Ligand-Gated Channel to open or close?

Answer 6

Specific extracellular neurotransmitter

Question 7

What are External and Internal channels in terms of gating?

Answer 7

External: neurotransmitter gated; Internal: cyclic nucleotide-gated

These channels open or close in response to specific molecules.

Question 8

What factors influence Mechanical-Gated and Temperature Gated channels?

Answer 8

Changes in conformation

Question 9

What does Patch Clamp measure?

Answer 9

Current flowing through a single ion channel

Question 10

What is the purpose of using a fine glass pipette in Patch Clamp?

Answer 10

To gently attach to the surface of a cell and measure electric currents

The pipette contains a special liquid that mimics the inside of a cell.

Question 11

What is cell-attached recording in Patch Clamp?

Answer 11

Pipette sticks to the cell without breaking the membrane, recording ion flow from a single channel

Question 12

What does whole cell recording involve?

Answer 12

Breaking open the membrane slightly to measure currents from all channels in the cell

Question 13

In inside-out recording, what is exposed to the controlled environment?

Answer 13

The inner part of the channel

Question 14

What happens in outside-out recording?

Answer 14

A membrane patch is pulled away so the outer part of the channel is exposed

Question 15

What is the purpose of using a K+ blocker when studying Na+ currents?

Answer 15

To ensure that only Na+ currents are observed

This technique isolates the Na+ current by preventing K+ from affecting the measurements.

Question 16

What characterizes the difference between microscopic and macroscopic currents?

Answer 16

Microscopic: 1 channel, macroscopic: >1 channel

Question 17

What causes neurons to become electrically active?

Answer 17

Changes in ion conductance (e.g., Na+, K+) and in membrane potential (Vm)

Question 18

When do voltage-gated Na+ and K+ channels open?

Answer 18

During depolarization

Question 19

What happens to Na+ channels during prolonged depolarization?

Answer 19

They become inactivated, entering a non-conducting state that is voltage-INdependent

Question 20

What is the role of the positively charged voltage sensor in voltage-gated channels?

Answer 20

It detects the potential across the membrane, causing the channel to open or close

Question 21

How does the closure of ion channels occur?

Answer 21

Closure (de-activation) is voltage-DEpendent

Question 22

What is the difference between inactivation and closure in ion channels?

Answer 22

Inactivation is voltage INdependent; closure is voltage DEpendent

Question 23

What sequential changes lead to action potentials?

Answer 23

Changes in voltage-gated Na+ and K+ permeability

Question 24

How do Na+ and K+ channels differ in their kinetics?

Answer 24

Na+ channels activate and inactivate quickly; K+ channels activate more slowly

Question 25

What regulates the shape and duration of action potentials?

Answer 25

Inactivation of Na+ channels and K+ channels

Question 26

What is the function of active transporters in neurons?

Answer 26

To create and maintain ion gradients

Question 27

What type of energy do active transporters require?

Answer 27

They require energy to function

Question 28

List the two types of active transporters.

Answer 28

* ATPase pumps * Ion exchangers

Question 29

What is the function of the Na+/K+ ATPase pump?

Answer 29

Maintains gradient for Na+ and K+ by hydrolysis (water is mostly used to break down the chemical bonds that exists between a particular substance)

Question 30

What is the role of the Ca2+ ATPase pump?

Answer 30

Prevents [Ca2+]i from accumulating

Question 31

Where is the PMCA pump found, and what does it do?

Answer 31

Found in plasma membrane; extrudes Ca2+ from the cell

Question 32

Where is the SERCA pump located, and what is its function?

Answer 32

Found in ER membrane; extrudes Ca2+ from the cytoplasm to store in ER

Question 33

What does the Na+ pump maintain?

Answer 33

Gradient for Na+ and K+ ## Footnote It uses the hydrolysis of ATP.

Question 34

How many Na+ ions are moved out and K+ ions moved in by the Na+ pump?

Answer 34

3 Na+ out/ 2 K+ in ## Footnote This process is electrogenic and essential for electrical charge differences in nerve and muscle activity.

Question 35

What is the significance of the conformational changes in the Na+ pump?

Answer 35

Associated with binding and hydrolysis of ATP ## Footnote The pump changes shape as it binds Na⁺, uses ATP, and releases Na⁺ outside before pulling K⁺ inside.

Question 36

What are ion exchangers?

Answer 36

Types of secondary active transporters ## Footnote They move ions or molecules across a membrane by using the energy from another ion’s movement.

Question 37

What do antiporters do?

Answer 37

Move two different ions/molecules in opposite directions ## Footnote Example: Na⁺/Ca²⁺ exchanger moves Na⁺ in while pushing Ca²⁺ out.

Question 38

What is the function of the Na⁺/Ca²⁺ exchanger?

Answer 38

Helps keep intracellular calcium levels low ## Footnote It moves 3 Na+ in and Ca²+ out, with conformational changes driven by ion binding.

Question 39

What do co-transporters do?

Answer 39

Move two different ions/molecules in the same direction ## Footnote Example: Na⁺/Glucose cotransporter (SGLT) moves Na⁺ and glucose into the cell together.

Question 40

What is the role of the Na⁺/Glucose cotransporter (SGLT)?

Answer 40

Helps absorb glucose in the intestines and kidneys ## Footnote It moves Na⁺ and glucose into the cell simultaneously.

Question 41

Fill in the blank: The transmembrane movement of ions by the Na+/Ca2+ exchanger helps keep [Ca2+] _______.

Answer 41

[Ca2+] low

Question 42

What stimulates the release of neurotransmitters in the context of the Na+/Ca2+ exchanger?

Answer 42

Conformational changes driven by ion binding ## Footnote This process occurs when 3 Na+ are moved in and Ca²+ is moved out.

Question 43

K+ blocker for patch clamp

Answer 43

cesium

Question 44

Na+ blocker for patch clamp

Answer 44

tetradotoxin