READING

Question 1

what is the difference between a neurotransmitter and a hormone?

Answer 1

• neurotransmitters are released in the brain
• hormones are released by the pituitary and travel in the bloodstream
• often structurally similar, the main difference between the two is the distance they have to travel

Question 2

what is the difference between the electrical information flow in the nervous system and the flow of electricity in a wire?

Answer 2

• the electrical information flow in the nervous system is much much slower than the flow of information through a wire
• this is because in the nervous system it is the passage of charged ions that carry the current and not the passage of electrons

Question 3

at resting potential, what side of the membrane has what charge?

Answer 3

the extracellular side of the membrane has a charge of -70mV relative to the intracellular charge of the membrane

the intracellular charge isnt actually 0 but we consider it 0 as when we look at potential differences we look at the extracellular charge relative to the intracellular charge

Question 4

What is the difference between proteins made on the RER and proteins made from free floating ribosomes?

Answer 4

• proteins designed to be inserted into the cell membrane are made on the RER. This is because as the protein is being assembled it is threaded back and fourth through the membrane of the RER where it is trapped.
• neurons have a lot of RER because they have a lot of membrane proteins
• proteins destined to reside in the cytosol of the neuron is made in free floating ribosomes

Question 5

what protein do microtubules consist of?

Answer 5

tubulin

Question 6

what protein are microfilaments made of?

Answer 6

actin

Question 7

what 3 structures make up the cytoskeleton in order of increasing size?

Answer 7

microfilaments
neurofilaments
microtubules

Question 8

what distinguishes the axon from the soma?

Answer 8

there are no RER in the axon and very few free ribosomes

The protein composition of the membrane is very different in the axon

Question 9

what is the name of axon branches?

Answer 9

axon collaterals

Question 10

what are neurites?

Answer 10

axons and dendrites

Question 11

How are dendritic spines correlated with intellectual disability

Answer 11

• intellectually disabled infacts have fewer dendritic spines and the ones they do have are abnormally long and thin
• the extent of the spine difference was well correlated with the degree of intellectual disability

Question 12

what is the difference between unipolar, bipolar and multipolar cells?

Answer 12

unipolar- neuron has a single neurite
bipolar- two neurites
multipolar- multiple neurites

Question 13

what is the difference between the pyramidal cells and the stellate cells in the cerebral cortex?

Answer 13

stellate cells are star shaped and are local circuit neurons

pyramidal cells are pyramid shaped and are projection neurons

Question 14

what are the 3 main types of neurons in terms of what connections are made?

Answer 14

primary sensory neurons
interneurons
motor neurons

Question 15

what is the difference between golgi type 1 neurons and golgi type 2 neurons?

Answer 15

golgi type 1

• otherwise known as projection neurons
• these have long axons that extend from one part of the brain to the other

golgi type 2

• otherwise known as local circuit neurons
• these have short axons that do not extend beyond the vicinity of the cell body

Question 16

whats the function of ependymal cells

Answer 16

• they line fluid filled ventricles within the brain

- they play a role in directing cell migration during brain development

Question 17

what is the equilibrium potential in relation to the membrane potential?

Answer 17

The equilibrium potential is the membrane potential that would balance out the ions concentration gradient so that no net ionic current would flow if the membrane were permeable to that ion

Question 18

are k+ ca2+ and na+ more concentrated inside or outside the membrane

Answer 18

k+ is more concentrated inside the membrane

ca2+ and na+ are more concentrated outside the membrane?

Question 19

which ways does the sodium pottasium pump transport ions across the membrane?

Answer 19

pumps na+ outside the membrane and k+ inside

uses atp as this is against the concentration gradients

Question 20

which way does the calcium pump transport calcium?

Answer 20

outside the membrane

uses atp as against concentration gradient

Question 21

what is the blood brain barrier?

Answer 21

a specialisation in the walls of the brain cappilleries that limits the movement of pottasium and other substances into the extracellular fluid of the brain

Question 22

do electrical synapses exist

Answer 22

yes

Question 23

where do electrical synapses occur?

Answer 23

gap junctions

gap junction often connect a neuron with a non neuronal cell, but they can connect two neurons in an electrical synapse

Question 24

what are connexins and connexons

Answer 24

the proteins present in electrical synapses, they combine to form connexon channels. two connexon channels can then combine to form gap junction channels that allow ions to directly transfer from one cell to another

Question 25

are electrical synapses directional or bidirectional?

Answer 25

they are bidirectional as gap junction channels allow ions either way

Question 26

what is a neuromuscular junction?

Answer 26

a chemical synapse between motor neurons in the spinal chord and skeletal muscle

Question 27

what is the post synaptic membrane of a neuromuscular junction called?

Answer 27

the motor end plate

Question 28

what are the 3 major categories of neurotransmitters?

Answer 28

amino acids amines peptides

Question 29

what is the difference between AMPA and NMDA receptors

Answer 29

AMPA are permeable Na+ and K+ NMDA are permeable to NA+ K+ AND Ca2+ NMDA-gated channels are voltage dependent this is because at normal resting potential the NMDA channel is clogged by Mg2+ ions. Mg2+ is only unclogged when the membrane depoarizes. This usually follows the activation of AMPA channels at the same synapse

Question 30

what two neurotranmitters mediate most inhibition in the CNS

Answer 30

GABA mediates most inhibtion | Glycine mediates most of the rest

Question 31

what ion do GABA and Glycine channels allow in

Answer 31

Cl- ions

Question 32

how do barbituates and benzodiazepines influence the GABAa receptors?

Answer 32

When GABA is present, benzodiazepines increase the frequency of channel openings and barbituates increase the duration of channel openings - this results in more CNS inhibition

Question 33

why does ethanol enhance inhibition in some brain areas and not others?

Answer 33

specific a,b and y subunits are nessercary for contructing an ethanol sensitive GABA

Question 34

what 4 main protein subtypes do drugs bind to?

Answer 34

receptors enzymes carriers ion channels

Question 35

what is the difference between agonists and antagonists?

Answer 35

agonists activate the receptors and antagonists block the receptors

Question 36

What is the difference between on target and off target side effects?

Answer 36

- on-target effects are unwanted side effects mediated through the same receptor as the clinically desired effects - Off-target effects are unwanted side effects arising from the action of a different receptor

Question 37

what is the difference between affinity and efficacy?

Answer 37

affinity is the tendency of a drug to bind to its receptors efficacy is the tendency of it, once bound, to activate the receptors

Question 38

what happens to the agonist log concentration-effect curve in the prescence of a competitive antagonist?

Answer 38

It shifts to the right, without a change of slope or maximum

Question 39

what is a dose ratio?

Answer 39

the ratio by which the agonist concentration has to be increased in the presence of the antagonist in order to restore a different level of response

Question 40

what is the relationship between the dose ratio and antagonist concentration?

Answer 40

there is a linear relationship between the dose ratio and the antagonist concentration

Question 41

What are 3 features of reversible competitive antagonism?

Answer 41

* shift of the agonist log concentration–effect curve to the right, without change of slope or maximum (i.e. antagonism can be overcome by increasing the concentration of the agonist) * linear relationship between agonist dose ratio and antagonist concentration * evidence of competition from binding studies

Question 42

what is irreversible competitive antagonism?

Answer 42

- Irreversible competitive (or non-equilibrium ) antagonism occurs when the antagonist binds to the same site on the receptor as the agonist but dissociates very slowly, or not at all, from the receptors, with the result that no change in the antagonist occupancy takes place when the agonist is applied - with irreversible competitve antagonism the antagonist reduces the maximum response, however this may be hard to detect if there are a lot of spare receptors

Question 43

whats stephensons formulation of efficacy?

Answer 43

- the reciprocal of the occupancy need to produce a 50% maximum response - e.g e= 25 implies that 50% of the maximal response occurs at 4% occupancy

Question 44

what is a full agonist?

Answer 44

a drug whose efficacy is sufficient that it produces a maximum response when less than 100% of receptors are occupied

Question 45

what happens to the dose response curve of a full agonist in the presence of a partial agonist

Answer 45

- it shifts the dose curve to the right | - so in effect the partial agonist can act as a competitive antagonist to the full agonist

Question 46

what is constitutive activation and what are inverse agonists

Answer 46

activation of a receptor when no ligand is present sometimes a drug can reduce the amount of constituent activation and they are known as inverse agonists

Question 47

why do agonists activate receptors and antagonists dont?

Answer 47

receptors have two states: Resting (R) and Active (R*) Agonists have a higher affinity for R* so cause a shift of the equilibrium to R* Antagonists have a neutral affinity for either R or R* Inverse agonists have a higher affinity for R

Question 48

What is biased agonism?

Answer 48

- some receptors can induce multiple different intracellular responses - Biased agonists are more likely to induce one particular intracellular response from the same receptor

Question 49

what is positive and negative affinity modulation?

Answer 49

positive modulation increases the affiity for the agonist, negative affinity modulation decreases it

Question 50

what are 6 different mechanisms that give rise to tolerance and desensitisation?

Answer 50

* change in receptors * translocation of receptors * exhaustion of mediators * increased metabolic degradation of the drug * physiological adaptation * active extrusion of drug from cells

Question 51

How can change in receptors lead to tolerance or desensitisation?

Answer 51

receptors can change so that: - agonists binding dont open the ion channel - receptors are desensitised by phosphorylation - phosphorylation causes the agonist to be less likely to induce a g-protein response

Question 52

how does translocation of receptors lead to desensitisation

Answer 52

prolonged exposure to agonists can lead to a decrease in the number of receptors, due to receptors being taken into the cell via endocytosis

Question 53

how does exuastion of mediators work

Answer 53

depletion of an essential substance e.g amphetamines cause the release of amines from the nerve terminals however the amine store can become depleted

Question 54

how does altered drug metabolism work

Answer 54

desensitisation can occur because increased metabolic degradation can lower the drug plasma concentration