Neurophysiology

Question 1

What was Luigi Galvani know for?

Answer 1

First appreciating that electricity is the primary force of our behaviour, explaining our fast reaction, as shown with his experiments on frogs

Question 2

What did Giovanni Aldini show?

Answer 2

That the whole nervous system communicates with electricity. He showed this by stimulating all muscles with cut nerve.

Question 3

Where is information integrated?

Answer 3

The dendrites

Question 4

Which type of potential is maintained at the same magnitude along the axon?

Answer 4

Action potential

Question 5

What happens to synaptic potential as it goes along?

Answer 5

It diminishes

Question 6

Where does signal summation occur?

Answer 6

At the cell body

Question 7

When will a neuron pass on the action potential?

Answer 7

If it reaches the threshold potential (-50mv)

Question 8

What is the threshold potential?

Answer 8

The minimum depolarisation required to initiate a nerve impulse, passing on the action potential (-50mv)

Question 9

What are gap junctions?

Answer 9

purely electrical synapses that allow electrical charge to cross directly between specialised channels (~10% of synapses)

Question 10

Where is an action potential generated?

Answer 10

At the axon initial segment/axon hillock

Question 11

Which type of neurite has the biophysical mechanisms to generate action potential?

Answer 11

Axons

Question 12

What type of mechanism is used to generate an action potential?

Answer 12

Voltage-dependent

Question 13

What does an intracellular recording measure?

Answer 13

The difference in current flow inside the neuron compared to a reference electrode outside, away from the neuron (differential recording)

Question 14

What does an oscilloscope do?

Answer 14

Tracks changes in potential difference over time

Question 15

What is resting membrane potential?

Answer 15

Approximately -65mv (more negative inside the neuron than outside)

Question 16

What is depolarisation?

Answer 16

The rapid rise in membrane potential initiated by an action potential, which, at its peak, become greater than outside of the membrane (around 30mv)

Question 17

What does an intracellular recording measure during depolarisation?

Answer 17

The flow of positively charged ions into the neuron, toward the electrode

Question 18

What is an extracellular recording?

Answer 18

A method of recording electrical activity whereby the recording electrode is placed outside of but very close to the neuron to measure an extracellular spike, with a reference electrode placed far away.

Question 19

What does an extracellular recording measure?

Answer 19

The flow of positively charged ions away from the electrode, into the membrane

Question 20

What is the purpose of the reference electrode in am extracellular recording?

Answer 20

To remove background electrical noise/events in the recording area

Question 21

What is the role of the phospholipid bilayer?

Answer 21

A barrier maintaining the compartment of the cell, helping to keep things from going in and out

Question 22

Why is water good at breaking down compounds/salts such as NaCl?

Answer 22

Because it is polar molecule

Question 23

What are membrane channels made of?

Answer 23

Multiple trans-membrane proteins forming a pore

Question 24

What are the three main types of membrane channels?

Answer 24

1. Simple leak channels
2. Ligand gated channels
3. Voltage gated channels

Question 25

What are leak channels?

Answer 25

A channel which is constantly open

Question 26

What is a ligand gated channel?

Answer 26

A channel which is opened when a substance binds to it (receptors that form the basis of neurotransmission)

Question 27

What is voltage gated channel?

Answer 27

A channel which opens when the voltage changes across the membrane, changing the structure of the proteins

Question 28

Which type of channel is important for the generation of an action potential?

Answer 28

Voltage gated channels

Question 29

Which type of channel is important for neurotransmission?

Answer 29

Ligand gated channel

Question 30

What is the most common (and important) ion pump?

Answer 30

The sodium-potassium ATPase pump

Question 31

What does the sodium potassium pump do?

Answer 31

It transports 3 Na+ ions out of the cell and brings in 2 K+ ions

Question 32

Why is the sodium potassium pump important?

Answer 32

To reestablish the resting membrane potential and ion gradients/balance needed to generate another action potential

Question 33

At rest, which ions are more concentrated in the extracellular space than inside the neuron?

Answer 33

Sodium (Na+), Chloride (Cl-), and Calcium (Ca2+)

Question 34

At rest, which ions are more concentrated inside the neuron than outside?

Answer 34

Potassium (K+) and organic anions (A-)

Question 35

What is the main ion involved in maintaining the negative membrane potential inside of a neuron?

Answer 35

Organic anions that are too big to cross the membrane

Question 36

What are the two forced involved in the movement of ions across the membrane?

Answer 36

Diffusion and electrostatic force

Question 37

Why is the net diffusion on K+ more limited than Na+?

Answer 37

Because the direction of the two forces oppose each other (it wants to diffuse out of the cell where there is less K+ but it's positive nature is electrostatically attracted to the intracellular space where it is relatively more negatively charged)

Question 38

Why do Na+ ions flood into the cell when given the opportunity?

Answer 38

Because they are under the dual aligned pressure of electrostatic force and diffusion.

Question 39

What is an intracellular sharps recording?

Answer 39

An incredibly fine glass pipette is filled with a solution of charged particles and pierces the phosholipid membrane to record electrical events

Question 40

What did John Eccles find?

Answer 40

That, using the sharps method, you can record the excitatory post-synaptic potential (a relatively slow electrical event) by stimulating presynaptic axons

Question 41

What is an EPSP?

Answer 41

An Excitatory Post-Synaptic Potential, the result of the opening on sodium channels and the influx of Na+ ions

Question 42

What type of receptor do nicotine, muscarine, and belladonna all act on?

Answer 42

Cholinergic receptors

Question 43

What are the two types of receptor involved in cholinergic transmission and where does this typically occur?

Answer 43

The nicotinic receptors and the muscarinic receptors at the neuromuscular junction.

Question 44

What type of channel is the nicotinic receptor?

Answer 44

Ligand gated ion channel - allows Na+ ions in when acetylcholine binds

Question 45

Which type of receptor mediates fast cholinergic transmission?

Answer 45

The nicotinic receptor (an ionotrophic receptor)

Question 46

What type of receptor is the muscarinic receptor?

Answer 46

A metabotropic/G-protein-coupled receptor

Question 47

Which type of receptor mediates slower cholinergic transmission?

Answer 47

Muscarinic receptors

Question 48

What does nicotine do to cholinergic transmission?

Answer 48

It binds directly to the nicotinic receptor, acting as an agonist

Question 49

How do muscarinic/G-protein receptors work?

Answer 49

They are attached to several proteins inside of the membrane which are released when the receptor changes shape due to acetylcholine binding, causing a cascade of the processes such as the opening of channels

Question 50

What are the three main receptors involved in glutamate transmission?

Answer 50

1. AMPA receptor 2. NMDA receptor 3. Kainate receptor

Question 51

Which receptor carries the majority of the synaptic current for fast excitatory (glutamate) transmission?

Answer 51

The AMPA receptor

Question 52

What is the NMDA receptor?

Answer 52

A voltage-dependent ionotrophic receptor involved in glutamate transmission, neuroplasticity, and learning.

Question 53

What is required for the activation of the NMDA receptor?

Answer 53

The presence of glutamate AND the depolarisation of the cell

Question 54

What is the major excitatory neurotransmitter in the brain?

Answer 54

Glutamate