brain, neurones, drugs and disease

Question 1

how many neurons

Answer 1

100 billion in average brain

Question 2

whether an action potential is generated depends on

Answer 2

size of voltage change reaching the axon hillock

Question 3

myelinated cells

Answer 3

schwann - PNS

oligodendrocytes- CNS

Question 4

neurolemma

Answer 4

plasma membrane surrounding all neurons

Question 5

at rest

Answer 5

neurolemma is negatively charged with respect to outside -70mv ‘polarised’

depolarisation gets more positive

hyperpolarisation gets more negative

Question 6

forces determining ion distribution

Answer 6

diffusion

electrostatic pressure

Question 7

depolarisation

Answer 7

Na ions in

Question 8

repolarisation

Answer 8

K ions out

Question 9

excitatory neurotranmistters

Answer 9

depolarise cell membrane

increase likelihood of action potential
cause an excitatory post synaptic potential (EPSP_

Question 10

inhibtoary neurotranmsitters

Answer 10

hyper polarise the cell membrane
decrease liklihood of action potential
cause inhibity post synaptic potential (IPSP)

Question 11

threshold

Answer 11

-60mV

Question 12

poison arrows

Answer 12

contain Ouabain (toxic subtance)
which is extracted from seeds of the African tress Strophanthus and Acokanthera ouabio

used as a dart poison for hunting

Blocks sodium/potassium pump, leading to an increase in intracellular sodium…

has become invaluable research tool in neuroscience

also used in low dose for treatment of heart failure

Question 13

lidocaine

Answer 13

widely used local anaesthetic
blocks voltage gated sodium ion channels
stops APs dead in their tracks
on WHO list of worlds essential medicines

think of sodium salt and lido(caine) cocaine also looks like salt

Question 14

myelin speeds propagation to

Answer 14

up to 150ms-1 (about 330 mph)

Question 15

MS

Answer 15

degeneration of myelin and development of scar tissue disrupts and eventually blocks neurotransmission along the myelinated axons

Question 16

Agatoxin//Atrocatoxin

Answer 16

derived from funnel web spider

blocks calcium channels

Question 17

vesicles contained ACh – how much?

Answer 17

2000-10,000 molecules of it

Question 18

fate of remaining neurotransmitter in the cleft

Answer 18

1) excess can keep firing post synaptic neutron
2) neuropeptides diffuse out of the cleft and destroyed by surrounding tissue
3) re-uptaken e.g. serotonin and noradrenaline
4) broken down- e.g. ach by acetylcholinesterase

Question 19

prozac

Answer 19

serotonin reuptake blocker

amitriptyline (serotonin and noradrenaline reuptake blcoker)

Question 20

why do we have brains?

Answer 20

promote survival and reproduction

avoidance of harm, body maintenance

sex and nurturing (sexual selection)

Question 21

functional defence systems

Answer 21

learned threat— cortex and limbic system – avoidance —motor

loom– sensorimotor midbrain– avoidance– autonomic

pain– spinal cord– escape–endocrine

Question 22

primary sensory areas processing info for the eye

example of specific function

Answer 22

visual cortex/midbrain superior colliculus

Question 23

primary motor structures providing commands for fine movements of fingers and mouth

(example of specific function)

Answer 23

hand area in motor cortex and trigeiminal motor nucleaus in brainstem

cortex (fingers)
mouth (trigeminal)

Question 24

generic functions

Answer 24

repeating micro-architecture that processes info received from regions performing widely different functions

Question 25

control of eye movement (example of sensorimotor function)

Answer 25

the midbrain superior colliculus input from the retina output to the eye muscles retinotropic maps of the visual world. evoked eye movements bring novel events onto the fovea (most sensitive part) where you focus: critical for effective visual perception

Question 26

examples of generic functions carried out by wide connections, general processing

Answer 26

sensorimotor calibration/skill episodic memory slection/attention reinforcement

Question 27

examples of specific functions carried out by specific structures

Answer 27

``` energy balance fluid balance temp regulation defence reproduction ```

Question 28

cerebellum

Answer 28

contains half totally number of CNS neurons 10% brain weight projects to most upper motor neurone damaged= jerky movement all sensorimotor, cognitibe and motivational/affective structures connect here

Question 29

hippocampus

Answer 29

generic processing system critical for episodic memory construction of mental images vital role in STM spatial mem and navigation

Question 30

basal ganglia

Answer 30

generic processing system 1. striatum (caudate, putamen and nucleus accumbens) 2. globus pallidus 3. subthalamic nucleus 4. substantia nigra well preserved system! selection: Deciding what to do amongst competing options Sticking with the choice until completed Avoiding distraction from less important stimuli reinforcement learning: Do things that have good consequences again!

Question 31

fast neurotransmitters - short lasting effects

Answer 31

ACh glutamate (excitatory) Gamma-aminobutyric acid (GABA) (inhibitory)

Question 32

neuromodulators (wider spread of connections and more subtle effects)

Answer 32

``` dopamine noradrenaline serotonin (5HT- 5 hydroxy-trypitamine) ```

Question 33

5 fundamental processes of synaptic transmission that drugs effect

Answer 33

1. manufacture 2. storage 3. release- by AP via voltage gated calcium channels 4. diffusion across cleft 5. inactivation- breakdown

Question 34

nicotine

Answer 34

affects binds to ach receptor (agonist)

Question 35

novichok

Answer 35

nerve agent that is a acetylcholinesterase inhibitor | stops normal breakdown of ach-esterase

Question 36

antagonists

Answer 36

interfere with how the molecule fits into the receptor

Question 37

Dales principle

Answer 37

'each neuron uses a single neurotransmitter' not strictly true! - many neurons release either GLU//GABA - but can also use several modulatory neurotransmitters - and modulatory systems can also be affected by other modularity neurotransmitters - e.g. pain modualtion

Question 38

hallucinogenic drugs

Answer 38

``` LSD Ketamine magic mushroom all mimic serotonin ```

Question 39

5-HT2a

Answer 39

serotonin 2a receptor

Question 40

endorphins

Answer 40

peptides with opiate like effects endorphins and opiates inhibit substance P subtance P- released by pain receptors opiates e.g. morphine induce changes in neuroplasticity so v addictive

Question 41

Parkinsons disease

Answer 41

first example of brain disorder that results from deficiency is single neurotransmitter lack of dopamine in the nigrostriatal dopamine pathway in the basal ganglia BG is critical for selection of behaviours esp movement - so patients find it hard to initiate movement as well as other cognitive symptoms

Question 42

drugs that affect dopamine

Answer 42

antipsychotics- chlorpromazine - receptor blocker stimulants - amphetamines/cocaine- increase release and block reuptake LDOPA- increases manufacture of dopamine

Question 43

dopamine prob in parkinsons

Answer 43

doesn't cross the blood-brain barrier- L dopa can though and it mimics it

Question 44

local anaesthics

Answer 44

procaine and ligocaine block Na channels (absorbed well through mucous membranes - 'EMLA cream'

Question 45

drugs noradrenaline is affected by

Answer 45

``` in perippheral (heart) and CNS ``` - antidepressants - Imipramine- blocks reuptake - antidepressants -MAO inhibitors- block break-down - stimulants (amphetamine- increases release and blocks re-uptake)

Question 46

drugs serotonin is affected by

Answer 46

antidepressants- prozac- reuptake inhibitor hallucinogens- LSD-5HT receptor agonist Ecstasy

Question 47

drugs GABA is affected by

Answer 47

anti-anxiety drugs- benzodiazepines- valium- inhibit effect at GABA receptors anticonvulsant drugs- also benzos anaesthetics- Barbiturates- potentiate the effect of GABA blocking info relay in thalamus

Question 48

GABA and the thalamus

Answer 48

The thalamus is a forebrain structure that ‘relays’ information from the sense onto ‘higher processing’ areas of the cortex The thalamus has a balance of excitatory (Glutamate) and inhibitory (GABA) neurotransmission Many general anaesthetics are GABA agonists….so they increase inhibition in the thalamus which blocks the relay of sensory information to the cortex