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BDS2.5 Applied Biomedical Sciences > Signal Transduction - Ion Channels > Flashcards

Signal Transduction - Ion Channels Flashcards

1
Q

What does Ligand binding to a receptor cause?

A

Conformational change in the protein receptor

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2
Q

Apart from being embedded in the cell membrane, where can receptors be found?

A

Nucleus or cytoplasm

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3
Q

When the agonist binds to the receptor, what does this allow? (Pathway)

A

Confo change and the receptor can activate the effector ligand and cause a signal transduction within the cell

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4
Q

Are signal transduction pathways conserved in the body?

A

Yes

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5
Q

What are the 4 major signal transduction pathways?

A

Ion channel

GPCR

Tyrosine kinase linked receptors (TKLRs)

Nuclear/intracellular receptors

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6
Q

What type of signalling molecule (ligand) activate the nuclear receptors?

A

Lipophillic ligand

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7
Q

What are the 2 types of ion channels?

A

Ligand gated

Voltage gated

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8
Q

What is an example of a ligand gated ion channel?

A

GABAa

GABAa binds to its receptor and allows Cl- to enter the cell

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9
Q

Where does benzodiazapine bind on the GABAa receptor?

A

Binds to an allosteric binding site, increase the affinity of binding for GABA molecules

GABA more likely to bind channel more likely to open and influx of chloride into the cell

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10
Q

How does the BDZ cause sedation?

A

Cl- into cell

Causes a negative intracellular charge, making it harder for an ap to occur and therefore causes sedation

no AP firing, supress CNS

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11
Q

Does BDZ cause the GABAa channel to open for longer or more frequently?

A

More frequently

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12
Q

Do barbiturates cause the GABAa channel to open for longer or more frequently?

A

Open for longer

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13
Q

What is the normal charge of the intracellular cytoplasm?

A

Negative

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14
Q

What is the only way for ions to cross the cell membrane?

A

Ion channels

Only way cells can redistribute charge

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15
Q

What charge of molecule causes the firing of an AP?

A

Sodium (positive charge)

Depolarise cell

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16
Q

What is the charge of a cell at rest? (intracellular)

A

-70mV

polarised

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17
Q

Why does the cell becoming less negative (more positive) make it easier to stimulate an AP?

A

Less negative, so need less additional positive charge to cause a stimulus

18
Q

Does benzodiazapine bind to the same or different (allosteric BS) from ligand?

A

Different

allosteric, increase affinity for GABA

hypopolarisation and harder to stimulate AP

19
Q

What channels does LA inhibit?

A

Voltage gated sodium channels

block AP

20
Q

What part of LA blocks the voltage gated sodium channel?

A

The amide side chain

21
Q

What 2 forms can LA exist?

A

Non-ionised and iodised

22
Q

From where do LA block sodium channels?

A

Penetrates the cell membrane in the non-ionised form (pass through cell), blocks channel in the ionised form from the inside (extra hydrogen)

23
Q

What forms can LA pass the membrane and block the channel?

A
24
Q

What does the balance of LA ionised and non-ionised depend on?

A

PH

25
Q

What pH drives the LA to the left? (LAH+)

A

To the left, more ionised state

acidic form

the inflamed tissue is acidic

26
Q

Why is LA less effective in inflamed tissue?

A

PH is lower (more acidic)

The La will take on the ionised form and cannot pass through the membrane

27
Q

What neurones is LA more effective in?

A

Small, rapidly firing neurons (e.g. pain fibres)

28
Q

Does LA show dependence?

A

Yes, the more the AP is fired the more effective the LA becomes.

29
Q

What are the 2 types of agonist?

A

competitive (bind to same BS as the agonist) - no conformational change of the receptor

non-competitive - bind to the allosteric BS

30
Q

What is an example of an ion channel receptor?

A

GABAa

31
Q

What is an example of GPCR receptor?

A

opioid receptors

32
Q

What is an example of a TKLR receptor?

A

growth receptor

33
Q

What is an example of a nuclear receptor?

A

steroid receptor

34
Q

How many GABA binding sites does the GABAa receptor have?

A

2

35
Q

What is a common BDZ in dentistry?

A

midazolam

= sedative

36
Q

Do barbituates cause anaesthesia or sedation?

A

sedation, increase duration of channel opening

they initiate anaesthesia

37
Q

Are ions lipophobic or lipophilic?

A

lipophobic, cant cross the membrane

38
Q

What channel does BDZ open?

A

ligand gated Cl- channels

39
Q

What part of the LA allows it to pass through the membrane?

A

lipid solubility of the aromatic region

40
Q

Why is there a constant supply of LA to pass through the membrane?

A

equilibrium

LAH+ is converted to LA

BDS2.5 Applied Biomedical Sciences (48 decks)

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