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Biology unit 1- Ms Byrne > Synapses > Flashcards

Synapses Flashcards

1
Q

what are synapses?

A

-junctions between the axon of one neurone and the dendron of another neurone

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2
Q

what are neurontransmitters?

A

-chemicals that transmit the impulse from one neurone to another

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3
Q

what is the synaptic cleft?

A

-the small gap that neurotransmitters have to pass across

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4
Q

what are the general names given to the neurones involved in synaptic transmission?

A

-pre synaptic neurone
-post synaptic neurone

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5
Q

what is the main job of the pre synaptic neurone?

A

-the neurone that releases the neurotransmitters

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6
Q

what is the job of the post synaptic neurone?

A

-receives the neurotransmitters via receptors

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7
Q

what structure does the end of the pre synaptic neurone? why? what does this structure contain?

A

-synaptic bulbs which contain large numbers of mitochondria which provides the energy for the production of the neurotransmitters
-synaptic bulbs are found at the end of the axon

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8
Q

how is the neurotransmitter stored?

A

-synaptic vesicles

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9
Q

look at the diagram of transmission at synapse on page 61

A

w

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10
Q

what is the name of the main neurotransmitter involved in impulse transmission?

A

-acetylcholine

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11
Q

what are the steps of impulse transmission (until the neurotransmitters received at the post synaptic neurone) what is the main neurotransmitter involved?

A

-when an impulse reaches the synaptic bulbs calcium channels open and calcium ions diffuse in
-the increase of these ions cause the synaptic vesicles to move tp the pre synaptic membrane
-the vesicles fuse with the membrane and release the neurotransmitter (acetylcholine) by exocytosis
-the neurotransmitter diffuses across the synaptic cleft and is received by the receptors

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12
Q

what happens during impulse transmission after the neurotransmitter has been received by receptors (until action potential is reached) in the post synaptic membrane?

A

-once received sodium channels open, positive sodium ions diffuse in causing the membrane to become depolarised which triggers an Excitatory Post Synaptic Potential (EPSP)
-once depolarisation reaches the threshold (depends on amount of receptor sites filled by neurotransmitters and amount of sodium ions) an action potential will occur in the post synaptic neurone

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13
Q

what happens during impulse transmission after the action potential has been reached in the post synaptic neurone? (in terms of the most common neurotransmitter acetylcholine)

A

-the enzyme will then break down the neurotransmitter into its products
-if the neurotransmitter was left in the receptor a new action potential could not happen
-in the case of acetylcholine the enzyme acetylcholinesterase will break it down to chlorine and ethanoic acid
-the products will then diffuse back across the synaptic cleft into the pre synaptic neurone
-they are re synthesised using energy provided by the mitochondria and the process begins again

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14
Q

what does EPSP stand for and what is it?

A

-excitatory post synaptic potential
-when the post synaptic neurone is rapidly depolarised by sodium ions which causes an action potential to be reached

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15
Q

what is the enzyme called which breaks down acetylcholine and what is it broke down into?

A

-acetylcholinesterase
-choline and ethanoic acid

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16
Q

what are 4 functions of synapses?

A

-nervous communication
-unidirectionality of impulses
-prevent overstimulation
-provide intergration

17
Q

how do synapses ensure unidirectionality?

A

-impulses can only pass from the pre synaptic to the post synaptic neurone as the neurotransmitter is only releases from the pre and received in the post by the receptors

18
Q

how do synapses prevent overstimulation?

A

-they control the supply of neurotransmitters to prevent fatigue of effectors e.g. muscles

19
Q

how do synapses provide integration?

A

-it can involve multiple pre synaptic neurones forming junctions with one post synaptic neurone
-provides flexibility

20
Q

by what process is integration aided by?

A

-process of summation

21
Q

what happens during the process of summation?

A

-a series of impulses that travel along the same neurone or a number of neurones operating in unison
-this releases a number of neurotransmitters which can reach a threshold to trigger an EPSP

22
Q

what are the 2 different types of synapses and what are their jobs?

A

-excitatory synapses which cause an EPSP and a subsequent action potential
-inhibitory synapses which make it more difficult for synaptic transmission to take place

23
Q

how do inhibitory synapses cause an IPSP (inhibitory post synaptic potential)?

A

-inhibitory neurotransmitters are released which leads to an influx of negative ions into the post synaptic membrane
-making the membrane more negative causing an IPSP
-

24
Q

how does an IPSP cause hyperpolarisation? how does this prevent an EPSP from occurring?

A

-due to the large amount of negative ions entering the post synaptic
-the neurone becomes even more negative than the normal resting potential
-makes it harder for excitatory synapses to reach a threshold for an action potential due the neurone being so negative

25
Q

why are inhibitory synapses important?

A

-reduces the the input of background stimuli to prevent overstimulation
-also prevents dome reflex actions

26
Q

what is the main transmitter involved in the CNS? and what is the main one involved in involuntary control?

A

-CNS- acetylcholine
-involuntary- noradrenaline

27
Q

how many neurotransmitters does each synaptic bulb produce?

A

-1

28
Q

what is the name of the transmitter released at inhibitory synapses? what does it do?

A

-GABA
-causes negative ions to flow into the post synaptic neurone causing hyperpolarisation
-helps to reduce anxiety by dampening nerve pathways in the brain

29
Q

how does nicotine effect the release of impulses? what transmitter does this effect primarily? is it stimulatory or antagonistic?

A

-causes release of acetylcholine
makes action potentials more likely
-stimulatory

30
Q

how does curare effect impulses and is it stimulatory or antagonistic?

A

-blocks receptors
-prevents synaptic transmission
-antagonistic

31
Q

how does opioids effect impulses and is it stimulatory or antagonistic? why can they be good sometimes?

A

-blocks calcium channels
-less transmitters released
-less action potentials
-antagonistic
-can provide pain relief

Biology unit 1- Ms Byrne (17 decks)

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