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SP604 > Synaptic Transmission > Flashcards

Synaptic Transmission Flashcards

1
Q

Communication witihin Neurons - Resting Potential, mV

A

-70mV

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2
Q

Communication witihin Neurons - Resting Potential, Na+

A

High Na+ inside the cell
Low Na+ outside the cell

Move in down electrochemical gradient

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3
Q

Communication witihin Neurons - Resting Potential, K+

A

Low K+ inside the cell
High K+ outside the cell

Move out down chemical gradient

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4
Q

Communication witihin Neurons - Excitation Threshold, mV

A

-55mV

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5
Q

Communication witihin Neurons - Excitation Threshold

A

If enough Na+ move into the cell, excitation threshold will be reached

Na+ channels will open, allowing an influx of Na+ into the cell, further depolarising the membrane

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6
Q

Communication witihin Neurons - Action Potential

A

Action potential is fired after excitation threshold has been reached

After firing, Na+ channels close and K+ channels open for repolarisation

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7
Q

Communication witihin Neurons - Action Potential, mV

A

30mV

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8
Q

Communication witihin Neurons - Refractory Period

A

Hyperpolarisation occurs as too many ions are taken out

Na+ / K+ pump redistributes charges
3 Na+ in, 2 K+ out, 1 ATP

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9
Q

Communication witihin Neurons - Refractory Period, Hyperpolarisation, mV

A

-80mV

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10
Q

Communication witihin Neurons - Refractory Period, Absolute

A

No stimulus could generate another action potential

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11
Q

Communication witihin Neurons - Refractory Period, Relative

A

A stimulus would need to be stronger than average in order to generate another action potential

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12
Q

Communication witihin Neurons - All-or-Nothing Principle

A

An action potential will only fire if excitation threshold is reached

Strength of a stimulus does not relate to the amount of depolarisation that occurs

If excitation threshold is not reached, and action potential will not be fired

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13
Q

Communication between Neurons - Neurotransmitters

A

Chemical substances released by the axon terminal after the arrival of an action potential

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14
Q

Communication between Neurons - Neurotransmitters, Mechanism

A

Ca2+ channels open at the presynaptic terminal when action potential arrives, with the influx of Ca2+ resulting in the release of neurotransmitters into the synaotic cleft

Neurotransmitters diffuse across the cleft and bind to complementary ligand-gated Na+ receptors in the postsynaptic membrane

If this binding blocks Na+, action potentials are inhibited
If this binging opens Na+ channels, another action potential is started in the next neuron

Neurotransmitters are then reuptaken or broken down and reused

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15
Q

Communication with Neurons - Excitatory Current

A

An action potential is propogated along the axon when Na+ difuse down the chemical gradient and depolarise the adjacent section of the membrane

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16
Q

Communication between Neurons - Neurotransmitters, Summation

A

One action potential from one neuron will not release sufficient neurotransmitter to generate an impulse in the next neuron therefore summation is required

17
Q

Communication between Neurons - Neurotransmitters, Summation, Temporal

A

Multiple impulses are sent along the same neuron in a short period of time

18
Q

Communication between Neurons - Neurotransmitters, Summation, Spatial

A

Multiple impulses are sent along different neurons at the same time

19
Q

Communication between Neurons - Neurotransmitters, Dopamine

A

Inhibitory

Allows feelings of pleasure and reward

20
Q

Communication between Neurons - Neurotransmitters, Serotonin

A

Inhibitory

21
Q

Communication between Neurons - Neurotransmitters, Acetylcholine

A

Excitatory

Allows motor control and coordination

22
Q

Communication between Neurons - Neurotransmitters, GABA

A

Inhibitory

23
Q

Communication between Neurons - Neurotransmitters, Glycine

A

Inhibitory

24
Q

Communication between Neurons - Neurotransmitters, Glutamate

A

Excitatroy

25
Q

Communication between Neurons - Neurotransmitters, Norepinephrine

A

Excitatory and Inhibitory

26
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Epilepsy

A

Epilepsy is a result of overexcitation
Anti-epileptics reduce excitation

Phenytoin binds to Na+ channels, blocking them from opening, meaning that Na+ cannot enter the cell and depolarise the membrane
Topiramate antagonises glutamate so it cannot excite neurons, blocks Ca2+ channels so they cannot stimulate the release of neurotransmitters into synaptic clefts
Clonezepam agonises GABA resulting in more inhibited impulses

27
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Mental Health

A

Increased dopamine levels result in schizophrenia, tourettes, OCD and mania
Decreased dopamine levels result in ADHA, depression and Parkinson’s

28
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Addiction

A

Addictive substances tend to stimulate the nucleus accumbens

This increases dopamine levels, increasing feelings of pleasure and decreases GABA resulting in increased excitation

29
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, DOPA

A

Increases dopamine levels

Used to treat Parkinson’s

30
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Cocaine

A

Increases serotonin, dopamine and norepinephrine

31
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Methyletalymine / Ritaline

A

Blocks reuptake of neurotransmitters resulting in slowed elongated excitation

Used to treat ADHD

32
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Amphetamine

A

Increases dopamine

33
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Antipsychotics

A

Block dopamine receptors

34
Q

Communication between Neurons - Neurotransmitters, Effects of Drugs, Alcohol

A

Antagonises Na+ channels, serotonin and glutamate
Agonises dopamine and GABA

Together these reduce responsivity due to enhanced inhibitory impulses, and associates with pleasure but acts as a depressant

35
Q

Communication between Neurons - Neurotransmitters, Loewi

A

Conducted a study with frog heart

Heart A was electrically stimulated in Beaker A
Heart A was removed from Beaker A and replaced with Heart B
Heart B showed activity despite no stimulation

Supports that there must have been a chemical released by Heart A that remained in Beaker A to stimulate Heart B

36
Q

Communication between Neurons - Neurotransmitters, Sherrington

A

Conducted research on reflexes and summation

Measured that transmission within neurons took place at 40 m / s
Transmission between neurons took place at 5 m / s

The difference in speed indicates that the mechanisms of communication differ for between and within neurons

SP604 (9 decks)

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