fundamental concepts

Question 1

What is resting membrane potential?

Answer 1

-Underpins the ability of neurons to generate signals and to communicate

-its an example of something called “electrical excitability”

-because the neuron is in an unstable state, upon a trigger that stored up energy is released and its the release of that energy that is the signal (action potential)

Question 2

What is electrical excitability?

Answer 2

when a neuron is not active energy is being is being expended (spent or used up) to maintain an unstable state

Question 3

What is action potential?

Answer 3

Triggered signals within a neuron that are electrical in nature

-Depends on the RMP

Question 4

What is happening within the resting membrane potential?

Answer 4

-the RMP depends upon the fact that the cell membrane of a neuron is a lipid bilayer
(two layers of fatty molecules) charged molecules don’t tend to pass through however it is leaky

-This membrane creates a barrier between the inside of a neuron and the outside of the neuron

Question 5

What are the 3 forces acting on the distribution of ions across the cell membrane?

Answer 5

Electrostatic pressure
Transporter
Diffusion

Question 6

Describe electrostatic pressure

Answer 6

-same charged ions repel each other and differently charged ions attract each other

-Positively charged ions will typically want to move into an area that is more negatively charged

Question 7

Describe Transporter

Answer 7

• moves specific ions
  -Uses energy (a substantial proportion of the energy consumed by the brain is in maintaining the RMP)

Question 8

Diffusion

Answer 8

Irrespective of the charge those ions will tend to want to move from areas of their high concentration to areas of low concentration

Question 9

Summarise the forces at work in relation to sodium

Answer 9

-There is a greater concentration of sodium outside than inside, so there is a diffusion gradient inducing sodium to want to go back into the cell
-The outside of the neuron is more positive than the inside and so there is electrostatic pressure as well pushing sodium inside
-While the cell membrane has a barrier it is slightly leaky and so some of the sodium can get through the membrane
-The transporter pushes it back out

Question 9

What is the structure of a synapse?

Answer 9

-made up of a presynaptic and postsynaptic terminal.

-The presynaptic terminal is at the end of an axon and is the place where the electrical signal (the action potential) is converted into a chemical signal (neurotransmitter release)

Question 10

What is neural integration?

Answer 10

-Each post synaptic neuron may receive inputs from many different pre synaptic neurons

-

Question 11

What is the difference between ESPS and IPSPS

Answer 11

PSPs are called excitatory (or EPSPs) if they increase the likelihood of a postsynaptic action potential occurring, and inhibitory (or IPSPs) if they decrease this likelihood.

Question 12

What are Ligands also referred to as

Answer 12

Neurotransmitter

Question 13

What is the binding site

Answer 13

place on receptor where the ligand interacts

Question 14

What are the two main concepts of binding the ligand to the receptor

Answer 14

Selective binding
Affinity

Question 15

Describe selective binding

Answer 15

-Only specific ligands will fit in a binding site
Due to the 3D shape of the receptor

-But some drugs bind to more than one receptor type

Question 16

Describe Affinity

Answer 16

-Essentially how well a ligand binds to a receptor

-High affinity means that receptors are saturated (completely bound) = a small amount of ligand binds to almost all the receptors

Question 17

What are the two types of receptor?

Answer 17

Ionotropic receptor
metabotropic receptor

Question 18

Describe the Ionotropic receptor

Answer 18

-Receptor is “directly coupled” to an ion channel

-Essentially true to say “the receptor is an ion channel”
Ligand binds = Ion channel opens

Question 19

Describe the Metabotropic receptor

Answer 19

-Ligand binds to receptor
-Changes 3D shape of receptor
-This activates a G-protein that connects to the receptor inside the neuron
-activating an intracellular signalling cascade

(Can alter ionotropic receptors to make them more or less excitable
Can alter protein synthesis)

Question 20

What are the two broad types of neurotransmitter

Answer 20

Amino acid derivatives
Monoamines

Question 21

What are the 3 main neurotransmitters within Amino acid derivatives

Answer 21

Glutamate
GABA
Glycine (technically an amino acid)

Question 22

What are the 4 main components of glutamate

Answer 22

-Derived from glutamic acid
-Most abundant neurotransmitter
-Excitatory
-Binds to at least 8 different receptors, both ionotropic and metabotropic (including NMDA and AMPA receptors)

Question 23

What are the 3 main components of GABA

Answer 23

-Made from glutamate
-Most abundant inhibitory neurotransmitter
-Binds to both ionotropic and metabotropic GABA receptors

Question 24

What are the main components of Monoamines

Answer 24

-Mostly bind to metabotropic receptors
-Found in restricted groups of neurons

Dopamine
Serationin (5-HT)
Neuropeptides (e.g, opioids)

Question 25

What two things can receptors in the presynaptic neuron cause?

Answer 25

Negative feedback
Retrograde signalling

Question 26

What is negative feedback in relation to receptors in the presynaptic neuron

Answer 26

release of neurotransmitter can stop its own further release

Question 27

What is retrograde signalling in relation to receptors in the presynaptic neuron

Answer 27

signal from postsynaptic neuron to presynaptic neuron; may be important for synaptic plasticity

Question 28

When and only when can receptors have its function

Answer 28

Receptors only have their function if they are bound in their binding site by the neurotransmitter ligand

Question 29

What is long term potentiation

Answer 29

-A process involving persistent strengthening of synapses

-A form of synaptic plasticity

-Bliss and Lomo (1973) discovered LTP, studied Rabbits hippocampus

Question 30

What 2 things might change to result in an altered post synaptic response to the same input nerve impulse?

Answer 30

NMDA receptors for induction

AMPA receptors for expression

Question 31

Describe NDMA receptors in relation to LTP

Answer 31

• ## NMDA Important for LTP to get started (Induction, also referred to as acquisition)-Channel is blocked by magnesium ion
  Two things need to happen in order for the NMDA receptor channel to open

1. Depolarise the membrane and this removes the magnesium block
2. Glutamate needs to be binding to the receptor
   -And when opened calcium can enter the postsynaptic neuron

-Essentially blocking NMDA receptors impairs the induction of LTP

Question 32

Describe AMPA receptors in relation to LTP

Answer 32

-AMPA receptors for expression

-Once LTP has started NMDA receptors are no longer needed for it to be expressed

-Many AMPA receptors are ionotropic so when glutamate binds to them there is a direct excitatory postsynaptic potential