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Biology > Synapses and drugs > Flashcards

Synapses and drugs Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How is the speed of impulse propagation increased?

A

by myellin

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2
Q

What is saltatory conduction?

A

action potentials are generated at the nodes of ranvier

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3
Q

What is synaptic transmission

A

pass on the action potential

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4
Q

Where is the action potential?

A

at the presynaptic neurone

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5
Q

What are the 2 alternatives to explain the process of synaptic transmission?

A

electrical- potential goes from one cell to next

chemical- chemical is released by pre-synaptic neurone

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6
Q

What is the evidence for chemical synaptic transmission?

A

Synaptic cleft- as its the section between the 2 neurones and if neurones are not touching each other then it cant be electrical
Synaptic delay- there is a delay of 0.5-0.8msec which means that a chemical must be involved unlike an electrical signal which is fast
Classic Otto Loewi experiment- 1 heart attached to a vagus nerve, whenn stimulating vagus nerve the heart would slow down. Then he attached 2 hearts with the vagus nerve and they both slow down. This could only happen from a chemical being released from a vagus nerve

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7
Q

What is the length of the synaptic cleft

A

30-40nm

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8
Q

What are electical synapses?

A

adjacent cells joined via gap junctions, thus ionic continunity between cells
fast but inflexible

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9
Q

What do gap junctions act as?

A

electrical synapse

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10
Q

What does it mean if the electrical synapse is inflexible?

A

you can transmitt action potential but cant modify action potential

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11
Q

Why are electrical synapses fast?

A

No neurotransmitter is released

action potential potential will go from neurone directly to the post synaptic neurone

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12
Q

Where are electrical synapse?

A

You have them in your heart and muscles of eye

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13
Q

What is the structure of a chemical synapse?

A

mitochondria
vesicles ( containing neurotransmitter)
synaptic cleft
post synaptic receptors

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14
Q

Why does the presynaptic area has lots of mitochondria?

A

its very energy intense

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15
Q

What are the inital stages of chemical synaptic transmission?

A
  1. the arrival of an action potential causes the influx of ca2+
  2. this causes the vesicle to migrate towards the presynaptic membrane
  3. here it fuses with the meembrane and releases the neurotransmitter via exocytosis
  4. the transmitter diffuses down the concentration gradient across the synaptic cleft and binds to post synaptic receptors changing the shape of the protein and ion channels open and diffuse
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16
Q

What can a single post synaptic cell receive their synaptic input from?

A

from several thousand presynaptic neurons

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17
Q

What is motor endplate?

A

junction between nerve cell and muscle cell

a neuromuscular junction

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18
Q

What is the experiment of recording from 2 points on a muscle fibre following neural stimulation?

A

1, A motor neurone is stimulated

  1. 2 electrodes put on muscle cell
  2. action potential recorded
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19
Q

What is an endplate?

A

when recording the action potential close to where the stimulus was, you have a positive bump

20
Q

What did the drug curare do?

A

Used a drug curarae
It stopped action potential in muscle cells- paraylsis/not able to move
Ended in endplate potential

21
Q

What is an endplate potential?

A

when the action potential on a muscle fibre can be abolished by curare, revealing the endplate potential (triggering the action potential)

22
Q

What is a neurotransmitter?

A

ACH

23
Q

how does ACH trigger action potential at neuromuscular junction ?

A

bind to receptors on the sarcolemma, opening sodium channels
leading to influx of sodium ions and an EPP
If threshold is reached, an action potential is generated

24
Q

What happens when ACH is on the muscle cell?

A

it will contract as ACH is released and triggered EPP, initiating depolarisation which triggers action potential on the muscle

25
Q

What was the experiment between 2 neurones?

A

stimulated motor neurons in the spinal cord of a cat

then recorded from post synaptic neuron

26
Q

What are the 2 neurons he used?

A

EPSP and IPSP

27
Q

What is inhibitory?

A

When taking it further away from threshold (getting more negative)

28
Q

What does the post synaptic cell do?

A

takes a decision whether fire or not depending on the potentials added together in the cell body

29
Q

What is EPSP?

A

excitatory postsynaptic potential

30
Q

What is IPSP?

A

Inhibitory postsynaptic potential

31
Q

How do you make postsynaptic cell negative IPSP?

A

caused by neurotransmitter opening CL channels and CL go in to neurone or
K+ open and K+ go out the cell
Both would hyperpolarise the cell and cause IPSP

32
Q

How do you make the inside of a neurone positive EPSP?

A 
Small depolarisation caused by neurotransmitter released
binding to receptors 
opening Na+ ion channels
Na+ go into the neurone
causes EPSP (depolarisation)
33
Q

What can neurotransmitters do?

A

alter ionic permability by binding onto postsynaptic membrane protein receptors (activation of receptors)
Only some neurotransmitters affect

34
Q

What are the 2 mode of action of transmitters?

A

Direct activation of an ionic channel (na+ etc)

Use of a secondary messenger

35
Q

What is a secondary messenger?

A

neurotransmitter released
binds to receptor which is not the ion channel, but it releases chemicals which act on ion channel and open or shut them.

36
Q

What are the 3 mechanisms of transmitter inacitvation (get rid of neurotransmitter such as ACH)?

A

Diffusion
Reputake- presynaptic neurone sucks neurotransmitter
Enzymatic breakdown (ACH-esterase)- breakdown of neurotransmitter

37
Q

Summary of events at a chemical synapse

A
  1. arrival of action potential causes influx of calcium ions
  2. calcium causes vesicles contraning neurotransmitter to migrate to presynaptic membrane
  3. transmitter is released via exocytosis
  4. transmitter migrates to postsynaptic receptors
  5. activation of receptors causes change in postsynaptic ionic permability
  6. transmitter inacitvation via reputake,diffusion and enzyme breakdown
  7. IPSP, EPSP (EPP)
38
Q

What is an example of another neurotransmitter?

A

nitric oxide

39
Q

What is dayls law

A

one neurone contains one neurotransmitter

40
Q

What are the 2 basic types of acetylcholine receptor?

A

nicotinic

muscarinic

41
Q

What does nicotinic receptor do?

A

it occurs at neuromuscular junction- ACH- open Na+ channels which therefore means its excitatory- muscles contract

42
Q

What does the muscarinic receptor do?

A

occur on heart-ACH- open K+ and Cl- channels- are therefore inhibitory

43
Q

What is the affect of ACH?

A

same neurotransmitter but 2 different effects depending on the receptor

44
Q

What is Agonists

A

drug that enhances effectiveness of a neuron- turn the neurone on

45
Q

What are antagonists

A

drug that supresses specific neurons- turn neuron off

46
Q

What do drugs do?

A

either enhance neurotransmission or depress

47
Q

What are the examples of the mode of action of a selection of therapeutic drugs?

A

L-dopa
Botox
Atropine
Prozak

Biology (30 decks)

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