Lecture 2: Resting Neuronal Membrane Potential

Question 1

What is the membrane potential of a neuron?

Answer 1

The membrane potential is the difference in charge across the neuron’s membrane.

Question 2

Q: How is the membrane potential created?

Answer 2

The membrane potential is created by the distribution of charged particles, called ions, across the membrane.

Question 3

What is the importance of membrane potential?

Answer 3

• Release of chemicals such as neurotransmitters
• Generation of action potentials

Question 4

Q: What is the resting membrane potential?

Answer 4

The resting membrane potential is the membrane potential when the neuron is at rest. In most neurons, it is around -70 millivolts (mV) relative to the outside environment.

Question 5

What does a change in membrane potential result in?

Answer 5

information and can generate action potentials

Question 6

What leads to the development of a concentration gradient?

Answer 6

an uneven distribution of ions and electric charge

Question 7

What is the movement of charge called?

Answer 7

current (I) which is measured in amps

Question 8

What is current dependent upon?

Answer 8

the potential difference (the difference in charge between the positive and negative poles) measured in volts
the ability of charge to move in a particular substance

Question 9

What allows for capacitance in a plasma membrane?

Answer 9

ions can interact across the neuronal membrane

Question 10

What is the role of ion transporters?

Answer 10

actively move ions against concentration gradients and create ion concentration gradients e.g. maintaining a high concentration of Na+ ions outside the cell and a high concentration of K+ ions inside the cell

Question 11

What are the two main types of ion transporter?

Answer 11

Na+/K+ pump and Ca2+ pump (ATPase pumps)

Question 12

How do ion exchangers work?

Answer 12

Ions move down their concentration gradient which allows them to move ions against their concentration gradient

One thing does what it will naturally do and the other one will go against its concentration gradient. It exchanges

Question 13

What does the ion concentration gradient represent?

Answer 13

potential - this forms the basis for neuronal signalling

Question 14

What are mechanically gated channels?

Answer 14

Mechanically gated channels are membrane proteins that open and close in response to mechanical forces, such as pressure, stretch, or vibration, allowing ions to flow in and out of the cell.

Question 15

What are ligand-gated channels

Answer 15

Ligand-gated channels are membrane proteins that open and close in response to the binding of a specific molecule (ligand) to the protein, allowing ions to flow in and out of the cell. (An example of ligand is a neurotransmitter)

Question 16

What are voltage gated channels?

Answer 16

Voltage-gated channels are membrane proteins that open and close in response to changes in the electrical potential difference (voltage) across the cell membrane, allowing ions to flow in and out of the cell.

Question 17

What are the different ways in which an ion channel can be gated?

Answer 17

voltage-gated, ligand-gated and mechanically-gated

Question 18

What allows for selectivity in ion channels?

Answer 18

the presence of a selectivity filter/core which is consisted of eight oxygen atoms arranged in a manner which allows for the corresponding ion to be energetically relaxed

Question 19

What is equilibrium in regards to concentration / electrical gradients?

Answer 19

equilibrium is the point at which the concentration and electrical gradients balance, such that there is no NET movement of an ion

Question 20

What generates the resting membrane potential?

Answer 20

The resting membrane potential is generated by the unequal distribution of ions across the plasma membrane, The result is a negative charge inside the cell relative to the outside.
It is generally induced by selective K+ permeability.

Question 21

In which electrochemical gradients is considerable potential stored within neurons?

Answer 21

electrochemical gradients of Na+ and Ca2+ across the membrane

Question 22

What are the main 3 principles responsible for the movement of charged particles.

Answer 22

1. Move along concentration gradient until equally distributed
2. Ions will move along an electrical potential gradient. (pos to neg)
3. Membrane resistance and Capacitance.

Question 23

Which ions can be found in high concentrations inside the cell

Answer 23

Potassium
Chloride (Sometimes)

Question 24

Which ions can be found in high concentrations outside the cell

Answer 24

Sodium (Most Times)
Chloride
Calcium (Sometimes)

Question 25

What are mechanically gated channels?

Answer 25

Mechanically gated channels are membrane proteins that open and close in response to mechanical forces, such as pressure, stretch, or vibration, allowing ions to flow in and out of the cell.

Question 26

What is the major determinant of the permeability of a membrane to a specific ion

Answer 26

Number of open ion channels specific for that ion

Question 27

Depolarization vs. Hypopolarization

Answer 27

Depolarization: decrease in the electrical potential difference (voltage) across the cell membrane, bringing the cell closer to the threshold required to generate an action potential.

Hypopolarization: a relatively small decrease in voltage that does not typically lead to an action potential.