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Extracellular signalling Flashcards

1
Q

Why do cells communicate together

A
  • regulate development
  • control growth & division
  • co-ordinate function
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2
Q

What happens when cellular communication goes wrong

A
  • signal lost (diabetes 1)
  • target ignores signal (diabetes 2)
  • signal doesn’t reach target (multiple sclerosis)
  • too much signal (brain damage)
  • multiple breakdowns (cancer)
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3
Q

What happens in diabetes 1

A
  • signal (insulin) lost

- pancreatic B cells no longer synthesise

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4
Q

What happens in diabetes 2

A
  • insulin ignored by defective target receptor
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5
Q

What happens in multiple sclerosis

A
  • nerve impulse not reach target

- breakdown of myelin sheath surrounding neurone

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6
Q

What happens in brain damage

A
  • excitetoxicity
  • too much glutamate neurotransmitter
  • neural degeneration
  • death
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7
Q

What happens in cancer

A
  • over-active
  • under-active
  • confused signalling
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8
Q

What are the three ways in which cells communicate (signal)

A
  • remote by secreted proteins
  • contact by plasma membrane-bound molecules (juxtacrine)
  • contact via gap junctions
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9
Q

What happens in contact via gap junctions

A
  • GJ join cytoplasm of interacting cells

- passage of signals

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10
Q

Give an example of gap junction

A

cardiomyocyte contraction (cc)

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11
Q

How do gap junctions in cc form

A
  • connexin protein expressed by adjacent cells
  • channel —> cytoplasmic content movement (2nd messenger)
  • rapid electrical; coupling
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12
Q

What protein make the gap junctions in the cardiac muscle

A

Connexin-43

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13
Q

What are the stages of remote signalling

A
  • reception
  • transduction
  • response
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14
Q

What are extracellular signal molecules referred to as

A

1st messenger

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15
Q

Give examples of 1st messenger

A
  • growth factors
  • neurotransmitters
  • hormones
  • cytokines
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16
Q

What are 1st messengers synthesised by

A

Signalling cells

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17
Q

What do 1st messengers have

A
  • specific response in target cells

- specific receptors

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18
Q

What are the four types of intercellular signalling

A
  • autocrine
  • paracrine
  • endocrine
  • neuronal
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19
Q

What happens in autocrine

A
  • cells respond to self-signals
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20
Q

What happens in paracrine

A
  • signalling acting on nearby cells
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21
Q

What happens in endocrine

A
  • signal released in blood
  • circulate
  • act on specific target
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22
Q

What happens in neuronal

A
  • response to nerve impulse
  • neurotransmitters released
  • act on target cells
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23
Q

What are hormones

A

Chemical messengers transport signal from one cell to another

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24
Q

Name two types of hormones

A
  • endocrine

- paracrine

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25
Where are endocrine hormones released into
- blood | - by endocrine glands
26
Where are paracrine hormones released into
- diffuse thru intestinal tissue
27
What do hormones regulate
- energy needs - protein & nucleic acid metabolism - mineral and electrolyte metabolism - synthesis and release of hormones
28
How is hormone activity regulated
- positive feedback | - negative feedback
29
Give examples of hydrophilic hormones
- catecholamines | - peptide hormones
30
Give examples of lipid-based hormones
- steroids - thyroid hormones - sterol hormones
31
Give examples of catecholamines
- adrenaline - noradrenaline - dopamine - serotonin - histamine
32
Give examples of peptide hormones
- insulin - glucagon - angiotensin II
33
Give examples of steroids
- oestrogen - testosterone - cortisol - aldosterone
34
Give examples of thyroid hormones
- thyroxine (T4) | - tri-iodothyronine (T3)
35
Give examples of sterol hormones
- calcitrol (Vitamin D)
36
What has to happen to signal of extracellular in order to have an effect
- convert into intercellular signal
37
What are receptors and what do they do
- co-ordinate functions of cells in response to signals | - shape complementary to messenger for interaction
38
Give an example of receptor subtype specific
Adrenaline - liver, muscle: glycogen degeneration - adipose: fatty acid production - cardiovascular: heart rate, bloop pres. up
39
What determines the class of a receptor
- molecular structure | - transduction mechanism
40
What are the two types of receptions
- cell-surface - hydrophilic | - intracellular - lipid-based
41
Name cell-surface membranes
- ligand-gated ion channel - G-protein coupled - tyrosine kinase
42
Name intracellular receptor
- nuclear hormone receptor
43
Describe ligand-gated ion channels
- ionotropic - very fast - synaptic transmission
44
Explain mechanism of ligand-gated ion channels
- binding —> conformational change - ions flow - cell electrical potential altered
45
Where are ligand-gated channels found | Where is binding site
- electrically excitable cells | - extracellular side
46
What is the structure of ligand-gated ion channels
4 or 5 heteromeric subunits | Central pore
47
Give examples of ligand-gated ion channels
- nAChR - GABAa - GlyR - 5-HT3R
48
How does nicotine acetylcholine receptor (nAChR) work
- in. Na+ & K+ permeability - Na+ in, K+ out - depolarisation
49
What are G-protein-coupled-receptors (GPCR)
- metabotropic | - heptahelical
50
What is the structure of GPCR
- single polypeptide chain - 7 a-helical regions —> intracellular & extracellular loops - NH2 terminus - COOH cytosolical terminus
51
What is a 2ry messenger
- small intracellular molecule | - formed in reception to receptor activation
52
What is Renin-Angiotensin system (RAS)
- feedback system
53
What does RAS control
- blood pressure - blood vol. - electrolyte homeostasis
54
What does RAS consist of
- renin | - angiotensin-converting enzyme (ACE)
55
What does renin (made in kidney) do
- cleaves a decapeptide from N-terminus from angiotensinogen (made in liver)
56
What is ACE
Membrane-bound dipeptidyl carboxypeptidase
57
What does ACE do
- cleaves C-terminal dipeptides from angiotensin | - producing angiotensin 2
58
What does Ang 2 do
- in. Sympathetic activity - water retention - aldosterone secretion - arteriolar vasoconstriction - in. Bp - ADH secretion
59
What is the structure of Ang 2
- peptide hormone | - octapeptide
60
What are the receptors of Ang 2
- GPCRs | - AT1, AT2
61
What effect does Ang ii have if bound to AT1
- vasoconstriction - increased NA - Na+ reabsorption - aldosterone secretion - vascular growth
62
What effect does Ang ii have if bound to AT2
Opposite AT1
63
What strategies are used to control RAS against HF
- inhibit renin release/ activity - ACE inhibitors - AT1 receptor antagonists (losaratan) - aldosterone receptor antagonists
64
What is the structure of kinase-linked receptors
- single transmembrane helix - large extracellular domain - intracellular catalytic domain - large & heterogeneous
65
Explain catalytic receptors (kinase-linked)
- receptor is enzyme - tyrosine kinase receptors - activated by insulin & growth factors
66
Explain non-catalytic receptors (kinase-linked)
- receptor act thru cytoplasmic tyrosine kinases - cytokines - growth hormones
67
What happens after ligand binding in kinase linked receptors
- receptor dimerisation - indirectly regulate transcription - cell division - tissue repair - apoptosis
68
What is the structure of nuclear hormone receptors
- monomeric - lipophilic hormones - separate ligand ; DNA binding domains
69
What do nuclear hormones receptors do
- regulate gene transcription
70
Examples of hormones that are acted on by nuclear receptors
- steroid hormones | - thyroid hormones
71
How do hormones affect gene transcription in nuclear receptors
- hormones diffuse across memb. - interact with cytosolic/nuclear receptors - hormone-receptor complexes - bind to DNA —> affect transcription
72
What do dendrites, cell bodies and axons do
- receive info. - assimilates info. - ends at nerve terminal
73
Describe neurotransmission
- action potential - synaptic vesicles fusing synaptic memb. - Ca2+ diff. in - neurotransmitter (ACh) released by exocytosis - neurotransmitter across syn cleft - binds to post-syn cleft - initiates response
74
What are neurotransmitters
Chemical messengers of nervous system
75
Give examples of neurotransmitters
- ACh - monoamines - amino acids - peptides - lipids
76
Give examples of monoamines neurotransmitters
- noradrenaline - adrenaline - dopamine - histamine - serotonin
77
Give examples of amino acids neurotransmitters
- glutamate - aspartate - glycine - GABA
78
Give examples of peptides neurotransmitters
- endorphins - substance P - neuroticisms - neurotensin
79
Give examples of lipids neurotransmitters
- anandamide
80
What is the life cycle of a neurotransmitter
- synthesis - storage - release - receptor activation - neurotransmitter inactivation
81
What are the two types of depression
- unipolar | - bipolar affective disorder
82
What neurotransmitters are deficited in depression
- noradrenaline - dopamine - serotonin
83
What are the treatments for depression
- monoamine reuptake inhibitors - Monoamine oxidase inhibitors (MAOIs) - miscellaneous antidepressants - electoconvulsive therapy (ETC) - mood-stabilising drugs
84
Give examples of monoamines reuptake inhibitors
- TCAs: tricyclics antidepressants - SSRIs: selective serotonin reuptake inhibitors - SNRIs: serotonin/noradrenaline reuptake inhibitors
85
What are the harmful effects of CO
- highly toxic - 50% of fatal poisoning - long term neurological & cardiovascular disorders
86
What are the benefits of CO
- endogenous signalling molecule - cardioprotective - neuroprotective
87
what is the role of antidepressants
increase monoaminergic transmission within the synaptic cleft

IMS (18 decks)

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