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ICPP > Session 1: Homeostasis & Signalling Molecules > Flashcards

Session 1: Homeostasis & Signalling Molecules Flashcards

1
Q

Muscle activity involves biochemical reactions that produce heat due to ________ being converted to ____________

A

ATP

ADP

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2
Q

Apart from conversion of ATP to ADP, heat is also generated by what?

A

Movement of muscle contractile proteins

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3
Q

What are the main extracellular signalling groups?

A

Endocrine
Paracrine
Autocrine

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4
Q

Endocrine signalling involves which class of molecule?

A

Hormones

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5
Q

What are the major types of endocrine signalling molecules/hormones?

A

Hydrophilic 1 - Amines (Chatecholamines) e.g. Noradrenaline
Hydrophilic 2 - Peptides to proteins e.g. Insulin
Lipophilic- Steroids e.g. Testosterone

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6
Q

What are the time courses of action of amines, proteins and steroids?

A

Amines: milliseconds - seconds
Proteins: minutes- hours
Steroids: hours- days

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7
Q

Where are the receptors for each of these type of extracellular signalling molecule?
Amines
Proteins
Steroids

A

Amines- within the plasma membrane
Proteins- within the plasma membrane
Steroids- Intracellularly, within the cytosol or nucleus

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8
Q

What is the plasma half life of:

1) Chatecholamines
2) Peptides to proteins
3) Steroids

A

1) Seconds
2) Minutes
3) Hours

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9
Q

What do exogenous analogous signalling molecules do?

A

They attempt to mimic endogenous signalling molecules

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10
Q

Give two examples of exogenous endocrine analogues and what they might be used for.

A

Adrenaline- administered IV in emergency situations

Insulin- allows adequate control of blood sugar in diabetic patients

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11
Q

What is paracrine signalling?

A

Signalling from one cell which induces change in nearby cells

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12
Q

Are paracrine signalling molecules are released intra- or extracellularly?

A

Extracellularly

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13
Q

Signalling molecules that signal from neurone to neurone are known as what?

A

Neurotransmitters

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14
Q

Multiple synapsing of the CNS allows what?

A

Parallel processing of information

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15
Q

Transmission velocity of neurotransmitters is measured in what?

A

Milliseconds

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16
Q

What common neurotransmitter is excitatory at the end organ?

A

Acetylcholine (ACh)

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17
Q

Give 4 examples of monoamine neurotransmitters? State whether they are stimulatory or inhibitory.

A

Adrenaline - stimulatory
Noradrenaline - stimulatory
Dopamine - stimulatory and inhibitory
Serotonin

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18
Q

Give three examples of amino acids that act as neurotransmitters? State whether they are excitatory or inhibitory.

A

Glutamate- Excitatory
Glycine- Mostly inhibitory
GABA- Inhibitory

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19
Q

Local chemical meditators can also be examples of _________ signalling molecules

A

Paracrine

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20
Q

Some local chemical mediators can be classified as ____________ and ___________

A

Cytokines

Eicosanoids

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21
Q

Give four examples of cytokines

A

Interleukins
Chemokines
Interferons
Histamine

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22
Q

Give two examples of Eicosanoids

A

Prostaglandins

Leukotrienes

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23
Q

Besides Cytokines and Eicosanoids name four other local chemical mediators

A

Bradykinin
Nitric Oxide
Neuropeptides
Platelet Activating Factor

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24
Q

When would local chemical mediators be released?

A

Following local injury

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25
Q

What are the advantages of eliciting a local response?

A

It is rapid, focused and integrated and does not need to involve the whole body resource

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26
Q

Give three examples of the therapeutic application of paracrine signalling molecules of the neurotransmitter variety

A

Dopamine precursors and agents- inhibit dopamine breakdown in Parkinsonism
Fluoxetine- SSRIs to slow the reuptake of Serotonin in the CNA in depression
GABA receptor modulators/reducers of GABA synthesis- In epilepsy

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27
Q

Therapeutic paracrine signalling molecules that act as local chemical mediators can be used to treat what?

A

Inflammation (Steroids)
Moderate pain (NSAIDs)
Respiratory Inflammation

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28
Q

What is autocrine signalling?

A

When cells respond to signalling molecules that they produce and release themselves

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29
Q

Autocrine signalling shares many signalling molecules what what other signalling type? Such as?

A

Paracrine signalling

Such as cytokines and growth factors

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30
Q

Autocrine signalling molecules typically act over what distances when released from the cell?

A

Microns (Micrometres)

31
Q

Endogenous and exogenous signalling molecules bring about a __________ in functional status

A

Change

32
Q

The signal produced when a signalling molecule binds its target can function to _______ the original signal to produce another signal, and ultimately perform a specific task e.g. _______ or ________

A

Transform
Transport
Synthesis

33
Q

Endogenous signalling molecules have been engineered by ____________ and therefore carry out their function optimally

A

Evolution

34
Q

Exogenous signalling molecules are often engineered by _________ _________ to carry and transfer their ‘imposter’ signal. The signal is still carried, but the _____ may be sub-optimal.

A

Human design

Fit

35
Q

Exogenous signalling molecules may produce unwanted _____________.

A

Side effects

36
Q

Name 4 classes of targets for signalling molecules

A

Receptors
Ion channels
Transporters
Enzymes

37
Q

Name the 4 types of RECEPTORS that signalling molecules may act on

A

Kinase-linked receptors
Ion channels (Ligand Gated!!)
Nuclear/intracellular
G Protein Couple Receptors (GPCRs)

38
Q

Name the three types of ion channels

A

Ligand gated
Voltage gated
GPCR modulated

39
Q

Kinase-linked receptors have a timescale of what?

A

Hours

40
Q

Kinase-linked receptors bind ligands such as?

A

Growth factors
Cytokines
Hormones

41
Q

How do kinase-linked receptors work?

A

Via phosphorylation of specific groups which activates a SIGNALLING CASCADE leading to gene transcription e.g. growth/differentiation

42
Q

Ligand gated ion channels are a type of receptor. What are these receptors also known as? What does this mean?

A

Ionotropic receptors

They form an ion channel pore

43
Q

What is the time scale of ligand gated ion channels?

A

Milliseconds

44
Q

Ligand gated ion channels gate the flow of _____ across the plasma membrane for the duration of ________

A

Ions

Binding

45
Q

Give some examples of ligands that may bind to a ligand-gated ion channel

A 
Neurotransmitters such as: 
Acetyl Choline (ACh), GABA and NMDA
46
Q

Ligand gated ion channels allow _____ currents and _________ change which can drive or modulate action potential generation in ________ and ________ in muscle

A

ion
voltage
neurones
contraction

47
Q

Nuclear/ Intracellular receptors have a time scale of what?

A

Hours

48
Q

In order to bind to a nuclear/ intracellular receptor, ligands need to be what?

A

Lipid soluble

49
Q

Once the ligand is bound, what happens at the nuclear receptor?

A

The ligand-receptor complex migrates to the nucleus, if it is not already there, and binds to a TRANSCRIPTION FACTOR

50
Q

Once the ligand-receptor complex is bound to a transcription factor, what happens?

A

A set of genes are activated or inactivated

51
Q

Apart from steroids, what other ligands can bind to nuclear/intracellular receptors?

A

Thyroid hormone, Vitamin D, Xenobiotics

52
Q

GPCRs are also known as what type of receptor?

What does this mean?

A

Metabotropic receptors

It is a membrane receptor that acts through secondary messengers

53
Q

What are the largest family of receptors?

A

GPCRs

54
Q

Give two examples of groups of molecules that can bind to GPCRs

A

Hormones

Opiates

55
Q

What is the time scale of GPCRs?

A

Seconds

56
Q

Give two examples of GPCRs that have ligands that are neurotransmitters

A

Musclarinic acetyl choline (ACh) receptor (serotonin) and adrenoceptors (dopamine)

57
Q

What are the three major types of GPCR?

A

Gq, Gi and Gs

58
Q

What is the difference between ionotropic and metabotropic receptors

A

Ionotropic: form an ion channel pore in the cell membrane
Metabotropic: acts by signal transduction through a secondary messenger

59
Q

Ion channels are another target of cell signalling molecule. How do they work?

A

By selectively allowing ion current to flow across the plasma membrane

60
Q

Name 4 major ion currents

A

Na+ (Sodium ions)
K+ (Potassium ions)
Ca2+ (Calcium ions)
Cl- (Chloride ions)

61
Q

Ion channels regulate voltage signals in excitable cells to maintain _________________

A

Membrane potential

62
Q

True of false: Ion channels are selective

A

True

63
Q

Voltage- gated ion channels (VGICs) primary activity is dependent on change in ______ ______ density

A

electric field

64
Q

Ion channel activity can be facilitated or inhibited by ___________ of intracellular sits on channels via GPCR Protein Kinase A and Protein Kinase C activation

A

Phosphorylation

65
Q

Activity of ion channels can be allosterically modulated by endogenous intracellular signalling molecules such as ______, _______ and Ca2+ signalling proteins e.g. _____________

A

ATP
GTP
e.g. Calmodulin

66
Q

Transporters/Carriers in the plasma membrane do what via which methods of movement?

A

Transport ions or small molecules using FACILITATED DIFFUSION or ACTIVE TRANSPORT

67
Q

With regard to movement of molecules, what features will determine whether movement is achieved by facilitated diffusion or active transport?

A

The concentration gradient (against a gradient=active transport)
The size of the molecule (large= active transport)
The polarity of the molecule (polar molecules= active transport)

68
Q

What energy sources are required to achieve active transport?

A

ATP or a pre-existing ion gradient (in symport/antiport)

69
Q

Which transporters are responsible for the efflux of drugs and imposter molecules from cells?

A

Multi-drug Resistance Proteins (MDRPs)

Part of the ATP-binding cassette ABC superfamily

70
Q

An important example of transport in the body is in neurotransmitter re-uptake. Give three examples of neurotransmitters that would be taken back up in this way.

A

Serotonin
Glutamate
Noradrenaline

71
Q

Co-transport of _____ can be used to drive transport. This type of transport is known as _________.

A

Na+ (Sodium ions)

Symport

72
Q

List 3 common uses of enzymes

A

Signal processing
Degradation
Synthesis

73
Q

Give an example of competitive inhibition at active binding site by a drug.

A

Aspirin binding to COX enzyme

ICPP (8 decks)

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