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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
What are the advantages of eliciting a local response?
It is rapid, focused and integrated and does not need to involve the whole body resource
26
Give three examples of the therapeutic application of paracrine signalling molecules of the neurotransmitter variety
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
27
Therapeutic paracrine signalling molecules that act as local chemical mediators can be used to treat what?
Inflammation (Steroids) Moderate pain (NSAIDs) Respiratory Inflammation
28
What is autocrine signalling?
When cells respond to signalling molecules that they produce and release themselves
29
Autocrine signalling shares many signalling molecules what what other signalling type? Such as?
Paracrine signalling | Such as cytokines and growth factors
30
Autocrine signalling molecules typically act over what distances when released from the cell?
Microns (Micrometres)
31
Endogenous and exogenous signalling molecules bring about a __________ in functional status
Change
32
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 ________
Transform Transport Synthesis
33
Endogenous signalling molecules have been engineered by ____________ and therefore carry out their function optimally
Evolution
34
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.
Human design | Fit
35
Exogenous signalling molecules may produce unwanted _____________.
Side effects
36
Name 4 classes of targets for signalling molecules
Receptors Ion channels Transporters Enzymes
37
Name the 4 types of RECEPTORS that signalling molecules may act on
Kinase-linked receptors Ion channels (Ligand Gated!!) Nuclear/intracellular G Protein Couple Receptors (GPCRs)
38
Name the three types of ion channels
Ligand gated Voltage gated GPCR modulated
39
Kinase-linked receptors have a timescale of what?
Hours
40
Kinase-linked receptors bind ligands such as?
Growth factors Cytokines Hormones
41
How do kinase-linked receptors work?
Via phosphorylation of specific groups which activates a SIGNALLING CASCADE leading to gene transcription e.g. growth/differentiation
42
Ligand gated ion channels are a type of receptor. What are these receptors also known as? What does this mean?
Ionotropic receptors | They form an ion channel pore
43
What is the time scale of ligand gated ion channels?
Milliseconds
44
Ligand gated ion channels gate the flow of _____ across the plasma membrane for the duration of ________
Ions | Binding
45
Give some examples of ligands that may bind to a ligand-gated ion channel
``` Neurotransmitters such as: Acetyl Choline (ACh), GABA and NMDA ```
46
Ligand gated ion channels allow _____ currents and _________ change which can drive or modulate action potential generation in ________ and ________ in muscle
ion voltage neurones contraction
47
Nuclear/ Intracellular receptors have a time scale of what?
Hours
48
In order to bind to a nuclear/ intracellular receptor, ligands need to be what?
Lipid soluble
49
Once the ligand is bound, what happens at the nuclear receptor?
The ligand-receptor complex migrates to the nucleus, if it is not already there, and binds to a TRANSCRIPTION FACTOR
50
Once the ligand-receptor complex is bound to a transcription factor, what happens?
A set of genes are activated or inactivated
51
Apart from steroids, what other ligands can bind to nuclear/intracellular receptors?
Thyroid hormone, Vitamin D, Xenobiotics
52
GPCRs are also known as what type of receptor? | What does this mean?
Metabotropic receptors | It is a membrane receptor that acts through secondary messengers
53
What are the largest family of receptors?
GPCRs
54
Give two examples of groups of molecules that can bind to GPCRs
Hormones | Opiates
55
What is the time scale of GPCRs?
Seconds
56
Give two examples of GPCRs that have ligands that are neurotransmitters
Musclarinic acetyl choline (ACh) receptor (serotonin) and adrenoceptors (dopamine)
57
What are the three major types of GPCR?
Gq, Gi and Gs
58
What is the difference between ionotropic and metabotropic receptors
Ionotropic: form an ion channel pore in the cell membrane Metabotropic: acts by signal transduction through a secondary messenger
59
Ion channels are another target of cell signalling molecule. How do they work?
By selectively allowing ion current to flow across the plasma membrane
60
Name 4 major ion currents
Na+ (Sodium ions) K+ (Potassium ions) Ca2+ (Calcium ions) Cl- (Chloride ions)
61
Ion channels regulate voltage signals in excitable cells to maintain _________________
Membrane potential
62
True of false: Ion channels are selective
True
63
Voltage- gated ion channels (VGICs) primary activity is dependent on change in ______ ______ density
electric field
64
Ion channel activity can be facilitated or inhibited by ___________ of intracellular sits on channels via GPCR Protein Kinase A and Protein Kinase C activation
Phosphorylation
65
Activity of ion channels can be allosterically modulated by endogenous intracellular signalling molecules such as ______, _______ and Ca2+ signalling proteins e.g. _____________
ATP GTP e.g. Calmodulin
66
Transporters/Carriers in the plasma membrane do what via which methods of movement?
Transport ions or small molecules using FACILITATED DIFFUSION or ACTIVE TRANSPORT
67
With regard to movement of molecules, what features will determine whether movement is achieved by facilitated diffusion or active transport?
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
What energy sources are required to achieve active transport?
ATP or a pre-existing ion gradient (in symport/antiport)
69
Which transporters are responsible for the efflux of drugs and imposter molecules from cells?
Multi-drug Resistance Proteins (MDRPs) | Part of the ATP-binding cassette ABC superfamily
70
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.
Serotonin Glutamate Noradrenaline
71
Co-transport of _____ can be used to drive transport. This type of transport is known as _________.
Na+ (Sodium ions) | Symport
72
List 3 common uses of enzymes
Signal processing Degradation Synthesis
73
Give an example of competitive inhibition at active binding site by a drug.
Aspirin binding to COX enzyme

ICPP (8 decks)

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