Lecture 2 - Communication in the brain

Question 1

what are glial cells

Answer 1

they make up half of the volume of the CNS and have support roles

Question 2

neuronal cell body

Answer 2

contains organelles and relays signals down to the axon

Question 3

dendrites

Answer 3

projections that receive signals from the neighbouring neurone, relays the information to the cell body

Question 4

axon

Answer 4

thin, long structures that transmits the signal from the cell body to terminal buttons - wrapped in myelin for rapid transmission

Question 5

axon terminals

Answer 5

transmits information outside the cell by neurotransmitters, which live in the terminal buttons.

Question 6

myelin sheath

Answer 6

insulting - 80% lipids, 20% protein

Question 7

oligodendrocytes

Answer 7

produce myelin

Question 8

astrocytes

Answer 8

supports the BBB

Question 9

microglia

Answer 9

help the repair process

Question 10

where is grey matter found in the cerebellum

Answer 10

surrounding white matter

Question 11

what is grey matter called in external areas

Answer 11

cortex

Question 12

what is grey matter called deeper in the brain

Answer 12

nuclei

Question 13

how is white matter organised

Answer 13

in tracts of axons

Question 14

how are grey and white matter organised in the spinal cord

Answer 14

it’s revered - white matter surrounds the grey matter

Question 15

what do neurones use to send messages

Answer 15

action potentials

Question 16

what is resting membrane potential

Answer 16

-70mV
as neurones have a negative concentration gradient, there are more positive ions outside rather than inside the cell - there are more sodiums outside and more potassium inside

Question 17

what channels are open during resting potential

Answer 17

potassium leak channels

Question 18

what creates an action potential

Answer 18

a depolarisation - causes the resting potential to move towards 0mV.

Question 19

When is an action potential fired

Answer 19

when the depolarisation reaches -55mV

Question 20

Outline the stages once and action potential is fired

Answer 20

1. sodium channels open causing sodium ions to enter the cell
2. this triggers more sodium channels to open
   potassium channels open, and potassium leaves the cell, reversing the depolarisation
3. at the same time sodium channels start to close
4. the cell returns to resting levels

Question 21

what is a hyperpolarisation

Answer 21

when the action potential goes past -70mV as potassium channels stay open too long

Question 22

what is the all or nothing principal

Answer 22

if threshold is not reached, no action potential will fire

Question 23

what are the 3 methods of signal termination

Answer 23

reuptake
diffusion
degration

Question 24

spatial summation

Answer 24

adds together all inputs received at the same time

Question 25

temporal summation

Answer 25

adds together inputs received at the same place but at slightly different times

Question 26

ligated ion channels

Answer 26

a type of receptor where there is rapid ion flow directly across the outer cell membrane 3-5 protein subunits for a pore when the neurotransmitter binds to the receptor, this open the pore and directly induces ion fluxes (fast acting)

Question 27

G protein coupled receptors

Answer 27

when the neurotransmitter associated with an extracellular recognition cite, a G protein is activated and opens/closes ion channels located at other places on the cell membrane (slow acting)

Question 28

inhibitory neurotransmitters

Answer 28

decrease the likelihood that the neurone will fire an action potential

Question 29

excitatory neurotransmitters

Answer 29

increase the likelihood that the neurone will fire an action potential

Question 30

what medical condition is associated with low levels of acetylcholine

Answer 30

alzheimers

Question 31

what do the medications donepezil, rivastigmine and galantamine do?

Answer 31

they prevent acetylecholinesterases from breaking down acetylcholine.

Question 32

what is glutamate

Answer 32

an amino acid neurotransmitter and the most abundant extort neurotransmitter in the brain which binds to a range of different receptors

Question 33

what is GABA

Answer 33

an amino acid neurotransmitter and the most abundant inhibitory neurotransmitter in the brain. it is produced from glutamate and binds to a range of receptors.

Question 34

what is glycine

Answer 34

an amino acid neurotransmitter that acts in the spinal cord, similar to GABA in the brain. a co-agonist.

Question 35

what are agonists

Answer 35

substances that bind to synaptic receptors and increase the effect of the neurotransmitter

Question 36

what are antagonists

Answer 36

substances that bind to synaptic receptors to decrease the effect of the neurotransmitter

Question 37

what are catecholamines

Answer 37

they help the body respond to stress or fright and prepare the body for 'flight or flight' actions epinephrine, norepinephrine and dopamine

Question 38

what are indolamines

Answer 38

found as discrete clusters of cells along the midline of the brain stem pathways projecting from the pons and midbrain to the cortex and limbic system as well as other areas of the CNS. they help with sleeping, eating and digestion

Question 39

what are the 3 treatments of depression

Answer 39

tricyclics, MAOI's and SSRI's

Question 40

explain how tricyclics work to treat depression

Answer 40

they block the reuptake of serotonin and norepinephrine in presynaptic terminals, meaning there is a higher concentration in the synaptic cleft

Question 41

how to MOAI's work in treating depression.

Answer 41

they prevent monoamine oxidase from removing norepinephrine, serotonin and dopamine from the brain

Question 42

how do SSRI's work in treating depression

Answer 42

the block the reabsorption of serotonin into neurones

Question 43

explain the use of MDMA 'ecstasy' on serotonin

Answer 43

more serotonin ends up in the synaptic cleft as ecstasy can prevent the transporters for carrying serotonin back to the terminal and can cause the transporter to in reverse and bring serotonin back to the synapse from the terminal