drugs and synapses Q&A

Question 1

whats the role of a synapse

Answer 1

space for neurotransmitters to reach different neurons- means neurotransmitters can reach many neurons not just one-creating simultaneous responses

many impulses can be combined at a synapse allowing stimuli from diff receptors to interact for a single response

Question 2

what is the function of acetylcholine in a synapse?

Answer 2

neurotransmitter to transmits impulses between neurones in a synapse
activates muscle action, plays a part in attention and awakening & involved in thought, learning and memory

Question 3

whats the role of calcium ions in a synapse

Answer 3

move down axon to transmit nerve impulse

Question 4

what do neurotransmitters do

Answer 4

neurotransmitters allow action potentials to be transported across a synapse

sodium ion channels on the postsynaptic neurone are usually closed but when a neurotransmitter binds to it it causes a conformational change and the channels open and sodium ions flood in causing depolarisation

contained in vesicles in the synaptic knob

Question 5

describe the 2 types of summation

Answer 5

summation amplifies nerve impulses
a single impulse may not be enough to generate an action potential so multiple impulses at once may be necessary

Question 6

what is an exitatory synapse

Answer 6

makes post synapse neurone membrane more permeable to Na ions

increases likelihood of post synaptic membrane depolarising

Question 7

what is an inhibitory synapse

Answer 7

Makes Post synaptic neurone less permeable to Na ions

decreases liklihood of post synaptic membrane depolarising

Question 8

what does acetylcholinesterase do?

Answer 8

hydrolyses acetylcholine into a separate acetyl and choline

Answer 9

O
||
C–OH

Question 10

compare and contrast synapses and neural muscular junctions

Answer 10

neuromuscular junctions are between a muscle cell and a neurone
a synapse is between 2 neurons

Question 11

what is divergence of nerve impulses?

Answer 11

When one nerve impulse can reach many neurones
this allows nerve signals to be sent in many dif directions from a single presynaptic neurone

Question 13

sodium potassium pump works how?

Answer 13

against a conc gradient- active transport

Answer 14

hypeerpolarisation useful as it keeps nerve impulse moving unidirectionally so it reaches the right effector

Question 15

what drugs can be taken to reduce effects of depression

Answer 15

SSRIS selective serotonin reuptake inhibitors

Question 16

l dopa

Answer 16

precursor to dopamine, becomes dopamine in the brain (lower levels of L dopa in the brain of someone with parkinsons)

Question 17

Whats an agonist

Answer 17

a drug or substance that binds to the receptor inside a cell or on its membrane and causes the same action as the substance that would usually bind to it

Question 18

whats a nerve

Answer 18

a group of neurones grouped together surrounded by a protective covering

Question 19

why cant dopamine be given directly to a parkinsons sufferer?

Answer 19

dopamine cant cross the barrier between blood and the brain

Question 20

how does l dopa become dopamine?

Answer 20

transported from the blood to the brain
converted to dopamine by dopa-decarboxylase
increases dopamine levels in brain

Question 21

how does giving parkinsons patients L dopa help them with movement

Answer 21

converted to dopamine in the brain
leads to an increase in dopamine in the brain
increased levels of dopamine mean more nerve impulses are transmitted in areas of the brain that control movement- lessening the symptoms of parkinsons

Question 22

how can drugs affect the events that happen at a synapse?

Answer 22

Drugs can increase transmission of impulses at a synapse by:

-Causing more neurotransmitter to be produced in the synaptic KNOB
-Causing more neurotransmitter to be released at the presynaptic MEMBRANE
-Imitating the effect of a neurotransmitter by binding to and activating receptors on the postsynaptic MEMBRANE
-Preventing the breakdown of neurotransmitters by enzymes
-Preventing the reuptake of neurotransmitters by the presynaptic CELL

Drugs can decrease transmission of impulses at a synapse by:
-Preventing production of neurotransmitter in the presynaptic knob
-Preventing the release of neurotransmitter at the presynaptic membrane
-Enabling neurotransmitter to gradually leak out of the presynaptic knob so there is little left when an action potential arrives
-The neurotransmitter that leaks out of the cell is destroyed by enzymes
-Binding to receptors on the postsynaptic membrane and so preventing neurotransmitters from binding

Question 23

whats the main neurotransmitter thats affected by MDMA

Answer 23

serotonin

Question 24

how does MDMA affect serotonin

Answer 24

-prevents reuptake of serotonin by presynaptic NEURONE by binding to specific proteins that enable serotonin uptake on the presynaptic membrane->this increases amount of serotonin in the brain
-serotonin levels for future action potentials will be reduced as usually serotonin will be reabsorbed into presynaptic membranes for future action potentials
-MDMA also triggers further release of serotonin from presynaptic neurones further adding to the increase

Question 25

what is habituation?

Answer 25

animals learn not to respond to a stimulus thats repeated multiple times with no negative outcome (detecting and responding to stimuli requires energy so habituation conserves energy)

Question 26

how does transmission of nerve impulses change with habituation?

Answer 26

-when habituation has taken place fewer calcium ions move into presynaptic neurone on arrival of nerve impulse -so less neurotransmitter released -so action potential less likely to be generated in postsynaptic neurone -less neurotransmitter released=less neurotransmitter binding to receptors on postsynaptic neuron membrane -impulse weaker so less sodium ion channels open -channels not open so fewer sodium ions move into axon->charge inside axon remains neg -threshold potential not reached so impulse doesnt reach effector organ