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ESA 2 > M And R > Flashcards

M And R Flashcards

1
Q

Name the four ways that phospholipids can move in the plasma membrane

A

Flexing, rotation, lateral movement and flip flop

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2
Q

Why can proteins not do flip flop?

A

There would be too large of a disruption to the plasma membrane which would probably result in rupture

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3
Q

How can we test if a protein sits on the inner membrane or outer membrane of the phospholipid bilayer?

A

Freeze fracture

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4
Q

Which two proteins are important for maintaining the cytoskeleton of the cell?

A

Actin and spectrin

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5
Q

Name two hereditary deficiencies to spectrin protein

A

Spherocytosis and elliptocytosis

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6
Q

Which two sites are important for protein integration into the plasma membrane?

A

The signal recognition particle (SRP) on the protein and the docking protein on the membrane

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7
Q

What properties must be displayed for a substance to diffuse through the plasma membrane?

A

Hydrophobic, small and uncharged

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8
Q

Name the four ways that membrane proteins can aid in transport of charged or large substances across a membrane

A

Facilitated diffusion
Ping pong
Ligand binding (e.g. nicotinic receptors)
Voltage sensitivity

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9
Q

Define equilibrium potential

A

The concentration at which there is no net movement of an ion in or out of the cell

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10
Q

What does the Goldman-Hodgkin-Katz equation tell us?

A

This is the overall equilibrium potential of the cell including all of the ions. Opening an ion specific channel in the cell will change the overall charge of the cell toward the equilibrium potential of that ion

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11
Q

What is the significance of a negative equilibrium potential of an ion?

A

The opening of these ion specific channels will hyperpolarise the cell. (Chloride and potassium)

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12
Q

How many transmembrane regions are in the voltage gated sodium channel? And how many subunits?

A

6 transmembrane regions and 4 subunits

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13
Q

In the voltage gated sodium channel, where is the pore located?

A

Between the fifth and sixth transmembrane region in all four of the subunits

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14
Q

Lidocaine is a use-dependent blocker of which channel?

A

Voltage gated sodium channel. This means that the channel must first open before being blocked

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15
Q

Describe the basis of neural accommodation

A

Depolarisation of the membrane allows sodium influx, further activating other voltage gated sodium channels. These take time to inactivate and so many impulses in quick succession makes the threshold incrementally higher with each impulse until threshold cannot be reached and an impulse is not conducted

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16
Q

Give the five subunits of the nicotinic receptor

A

2 alpha, 1 beta, 1 delta and 1 gamma

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17
Q

Acetylcholine binds to which subunit of the nicotinic receptor?

A

The two alpha subunits, causing the central pore to open and allow sodium influx

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18
Q

What is the local current theory of conduction?

A

Immediate local change to an axonal polarisation that is not propagated

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19
Q

Why is myelin used to surround axons?

A

It is a good conductor of impulses

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20
Q

At what diameter is myelination detrimental to conduction velocity?

A

1 micrometre

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21
Q

What is saltatory conduction?

A

Propagation of a signal down an axon jumping between the nodes on Ranvier

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22
Q

How is acetylcholine released into the synapse?

A

It is held within a vesicle, which binds to the presynaptic membrane by a snare complex and synaptotagmin. When the impulse arrives, calcium influx binds to the snare complex and create a fusion pore for the ACh to be released into the synapse

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23
Q

Define affinity

A

The tendency of a receptor to bind to a ligand

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24
Q

Define efficacy

A

The intrinsic response that occurs within a cell as a result of binding to a receptor

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25
Q

Give the unit of measurement of affinity

A

Kd - the concentration of substrate at which half of the receptors are occupied. Low Kd means a high affinity

26
Q

Explain the difference between a receptor and an acceptor

A

A receptor binds the ligand and initiates a response internally whereas an acceptor only binds the ligand and has no associated response

27
Q

Define drug potency

A

The concentration at which the drug is required to induce a specific response. This is affinity + efficacy

28
Q

How do we measure efficacy of a drug?

A

Give the highest possible concentration of the drug so that all receptors are occupied and only internal response is measured. This is the Emax

29
Q

Give the unit of measurement for drug potency

A

EC50 - the concentration at which half Emax is elicited

30
Q

What structure of clathrin coated pits allows for receptor mediated endocytosis (RME)?

A

The triskelion

31
Q

Once the ligand and receptor are taken up by a cell in RME, what structure do they enter?

A

The compartment of uncoupling of receptor and ligand (CURL)

32
Q

What is the fate of the ligand and receptor in RME for ferric ions?

A

Both recycled

33
Q

What is the fate of the ligand and receptor of insulin in RME?

A

Ligand recycled, receptor degraded

34
Q

What is the fate of the receptor and ligand of LDL in RME?

A

Receptor recycled and ligand degraded

35
Q

How many transmembrane domains are there in a G protein coupled receptor?

A

Seven

36
Q

Give the two subunits associated with a GPCR

A

Alpha and beta-gamma

37
Q

How do the alpha and beta-gamma subunits dissociate and associate in GPCRs?

A

Alpha subunit is initially bound to GDP
Stimulation of GPCR causes GTP to displace GDP
Beta-gamma subunit freed and exerts effects in the cell
Alpha unit slowly hydrolyses GTP to GDP by GTPase enzyme
GDP presence increases affinity for beta-gamma again

38
Q

Give the three forms that an alpha subunit of a GPCR can take

A

S, i and q

39
Q

Which enzyme do Gas and Gai act on?

A

Adenylyl cyclase

40
Q

What is the function of adenylyl cyclase?

A

Convert ATP to cAMP. cAMP will stimulate protein kinase A and cause a signal amplification

41
Q

Give the process occurring after Gaq stimulation

A

Stimulates phospholipase C to convert PIP2 into DAG and IP3. IP3 binds to sarcoplasmic reticulum to release calcium into the cytosol. The released calcium and DAG activate protein kinase C to cause signal amplification. The calcium is often utilised in muscle contractility

42
Q

How does calcium enter a cardiac myocyte?

A

Depolarisation of the membrane causes the voltage operated calcium channel to open

43
Q

Describe calcium induced calcium release

A

Voltage operated calcium channels open to allow calcium into the cell. This binds to a ryanodine receptor on the sarcoplasmic reticulum and allows calcium to be released from the sarcoplasmic reticulum.

44
Q

Give the role of calcium in myocyte contraction

A

Binds to the troponin complex to move the tropomyosin away from the myosin binding site, allowing the myosin head to bind

45
Q

Which calcium channel is important for the maintenance of the resting membrane potential?

A

Sodium calcium exchanger (NCX). Extrudes calcium for sodium influx

46
Q

Which portion of the spine has sympathetic outflow?

A

Thoracolumbar (T1-L2)

47
Q

Which portion of the spine has parasympathetic outflow?

A

Sacral and cervical

48
Q

Where in the autonomic system are nicotinic receptors found?

A

The pre-ganglionic synapses of both the parasympathetic and sympathetic fibres

49
Q

Where are muscarinic receptors (using ACh) found in the autonomic nervous system?

A

Post-ganglionic synapses of the parasympathetic division

50
Q

Where are adrenoceptors (using noradrenaline) found in the autonomic nervous system?

A

Post-ganglionic synapses of the sympathetic division

51
Q

How is acetylcholine removed from the synapse space?

A

By acetylcholinesterase enzyme breaking it down to acetate and choline

52
Q

How is acetylcholine made in the pre-synaptic bulb?

A

Made using choline acetyltransferase (CAT) and packed into vesicles using vacuolar ATPase

53
Q

How is noradrenaline removed from the synaptic space?

A

It is taken back up into the pre-synaptic bulb and broken down by monoamine oxidase (MAO)

54
Q

What is the mechanism of action of AChE inhibitors and what conditions are they used for?

A

These block acetylcholinesterase activity and keep the acetylcholine concentration high. Used for Parkinson’s disease and myasthenia gravis

55
Q

What is the mechanism of action of MAO inhibitors and what conditions are they used for?

A

These block monoamine oxidase enzyme and so noradrenaline is not degraded and so more persists in the synapse. This is used for depressive or anxious patients.

56
Q

Why is salbutamol favoured over salmeterol for asthmatics?

A

Salbutamol is a selective beta 2 agonist whereas salmeterol is not and so may induce tachycardia

57
Q

Between which two values is the therapeutic value found?

A

LD50 and ED50

58
Q

What is a precipitant (class II) drug?

A

One that displaces the original drug from binding blood proteins so that the first has a higher circulating concentration

59
Q

Describe first order drug metabolism kinetics

A

The rise in drug concentration is met by a proportional increase in product concentration

60
Q

Describe zero order drug metabolism kinetics

A

All of the enzymes are saturated and so a rise in drug concentration will not affect the rate at which product is made

ESA 2 (2 decks)

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