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Biomedical Physiology > Cell Signalling > Flashcards

Cell Signalling Flashcards

1
Q

Cell to cell communication can be of two types, what are these?

A

Direct and indirect cell communication

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2
Q

What are the four principle types of cell signalling in animals?

A

Direct - gap junctions
Autocrine and paracrine signalling
Endocrine signalling
Neural signalling

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3
Q

Describe how direct signalling may take place.

A

Adjacent cells may communicate directly through aqueous pores - GAP JUNCTIONS

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4
Q

Describe the process of indirect cell signalling in four stages

A
  1. Cell releases chemical messenger to extracellular env
  2. Chemical messenger transported to target cell
  3. Communication of signal to target cell via receptor binding
  4. Signal transduction pathways activated that cause a response within the cell
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5
Q

On what scale does the indirect cell signalling of paracrines work?

A

On a local scale

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6
Q

In paracrine cell signalling, how do the chemical messengers travel from the signalling cell to the target cell?

A

By diffusion

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7
Q

On what scale does the indirect cell signalling method of autocrines work?

A

Local scale

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8
Q

What is the difference between autocrine and paracrine cell signalling?

A

With autocrine signalling, the chemical messenger causes a response in the signalling cell whereas with paracrine signalling, the chemical messengers target a nearby cell

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9
Q

On what scale does endocrine cell signalling work?

A

Long distance

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10
Q

How does the chemical messenger travel in endocrine signalling?

A

In the circulatory system

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11
Q

What are endocrine messengers?

A

They are hormones

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12
Q

In neural signalling which is a type of indirect cell signalling, how is the signal transferred to the target cell in terms of distance?

A

Short distance

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13
Q

In neural singalling, the electrical signals travel over ____ distances within a single cell.

A

Long

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14
Q

Chemicals can be either h____ or h____

A

Hydrophobic or hydrophilic

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15
Q

Hydrophobic chemical messengers are soluble in

A

Lipids

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16
Q

Hydrophobic chemical messengers can/can’t pass through cell membranes

A

CAN

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17
Q

Hydrophobic messengers do/do not dissolve in aqueous fluids such as the cytoplasm or the blood

A

DO NOT

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18
Q

Hydrophilic chemical messengers are soluble in

A

Aqueous solutions

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19
Q

Can hydrophilic chemical messengers pass through cell membranes?

A

No

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20
Q

Are hydrophilic chemical messengers soluble in the cytoplasm and ECF?

A

YAS

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21
Q

There are six main classes of chemicals involved in cell signalling, what are these?

A

Peptides, steroids, amines, lipids, purines and gases

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22
Q

Peptides, steroids and amines are all known

A

hormones

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23
Q

The six main classes of chemicals involved in cell singnalling can be involved in

A

autocrine, paracrine and neurotransmitter cell to cell singalling

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24
Q

Peptide messengers can exist as what three types?

A

Amino acids, peptides and proteins

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25
Q

What are amino acids normally involved in cell signalling as?

A

Neurotransmitters

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26
Q

What are peptides normally involved in cell singalling as?

A

Autocrines, paracrines, neurotransmitters, neurohormones, hormones and pheromones

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27
Q

What are proteins normally involved in cell signalling as?

A

Autocrines, paracrines, neurotransmitters, neurohormones, hormones and pheromones

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28
Q

What is the difference between peptides and proteins in terms of amino acids?

A

Peptides 50 AA

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29
Q

What is a neurohormone?

A

A substance produced by nerve cells (neurosecretory neurones) and secreted into the circulation

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30
Q

Give two examples of neurohormones

A

Vasopressin and adrenaline

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31
Q

Are peptide messengers hydrophobic or hydrophilic?

A

Hydrophilic

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32
Q

Where are peptide messengers synthesisied?

A

In the rough ER

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33
Q

Peptide messengers are packaged into

A

vesicles

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34
Q

Peptide messengers can be used immediately or

A

stored

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35
Q

What type of peptide messengers are stored?

A

Peptide hormones and neurotransmitters

36
Q

What type of peptide messengers are made on demand?

A

Paracrine peptides such as cytokines

37
Q

How are peptide messengers released from the cell?

A

By exocytosis

38
Q

What is exocytosis?

A

When a secretory vesicle fuses with the plasma membrane releasing the vesicle contents to the cell exterior

39
Q

How are peptide messengers transported?

A

Easily through aqueous solutions

40
Q

What happens to peptide messengers in the extra cellular fluid?

A

They are broken down in the ECF by proteolytic enzymes

41
Q

What is the half life of peptide messengers?

A

The rate of breakdown of the peptide messengers by the proteolytic enzymes present in the ECF

42
Q

Is the half life of peptide messengers short or long?

A

Short - few seconds - few hours

43
Q

Why must peptide messengers be produced at a constant rate for a sustained response?

A

Because they have a short half life so won’t have a lasting effect

44
Q

What is the issue with peptide messengers reaching their target cell?

A

Peptide messengers are hydrophilic so cannot cross the plasma membrane easily

45
Q

How do peptide messengers cause a response in their target cell as they cannot cross the plasma membrane easily.

A

They bind to transmembrane receptors, conformational change of receptor, activated singal transduction pathways

46
Q

What are steroid messengers derived from?

A

cholestrol

47
Q

Steroid messengers can be which types of messenger?

A

Hormones in vertebrates and invertebrates, paracrine/autocrine in some tissues and pheromones in animal-animal communication

48
Q

There are three classes of steroid messengers in vertebrates, what are these?

A

Mineralocorticoids, glucocorticoids and reproductive hormones

49
Q

Give an example of a steroid messenger from the class mineralocorticoids.

A

Aldosterone - sodium reabsorption

50
Q

Give an example of a steroid messenger from the class glucocorticoids

A

Cortisol - manage stress & metabolism

51
Q

Give two examples of steroid messengers from the class of reproductive hormones

A

Eostrogens and testosterone

52
Q

How are steroid hormones synthesised?

A

Enzymes for steroid biosynthesis located in smooth er or mitochondria

53
Q

How are steroid hormones secreted?

A

Directly through the membrane because they are hydrophobic -

54
Q

Can steroid hormones be stored?

A

No because they are hydrophobic

55
Q

At which distance can steroid messengers be transported?

A

Short and long distance

56
Q

How are steroid messengers transported short distances?

A

By diffusion - dissolved in the extracellular fluid

57
Q

How are steroid messengers transported long distances?

A

By being bound to carrier proteins

58
Q

Steroid messengers can travel long distances by specific or non specific carrier proteins, give an example of a specific and an example of a non specific carrier protein.

A

Specific - globulins and non specific - albumin

59
Q

Steroid messengers are transported either bound to a carrier protein or as…

A

free messengers

60
Q

What percentage of steroid messengers are transported bound to a carrier protein and what percentage of steroid messengers are transported as free messengers?

A

Over 99% are bound to a carrier protein and below 1% are transported as free messengers

61
Q

What is the equation of law of mass action and equilibrium and what does each letter stand for?

A

M + C ->-

62
Q

What happens in the law of mass action and equilibrium in terms of steroid messengers?

A

Local conc of messenger is high near signalling cell
Most of messenger binds to carrier proteins
circulatory sys carries free and bound to target cell
Free messengers enter target cell
decresed conc of free messenger
causes bound messenger to dissociate from protein and also enter cell

63
Q

How do steroid messengers interact with the target cell?

A

By binding to the receptors to exert an effect

64
Q

What are the two types of receptors steroid messengers may bind to?

A

Transmembrane and intracellular receptors

65
Q

What is an intracellular receptor?

A

Intracellular receptors are receptors located inside the cell rather than on its cell membrane.

66
Q

What is a transmembrane receptor?

A

This type of receptor spans the plasma membrane

67
Q

When a steroid messenger binds to intracellular receptors what happens?

A

Act as transcription factors > control expression of target genes
• Pathway involves transcription & translation > time lag

68
Q

When a steroid messenger binds to a transmembrane receptor, what happens?

A

Binding activates signal transduction pathway

• Causes rapid non-genomic effect

69
Q

What are biogenic amines?

A

A chemical messenger obviously but chemicals containing an amine group attached to carbon atom

70
Q

What is an amine group?

A 
Amine group (-NH2
)
71
Q

Are biogenic amines hydrophobic or hydrophilic?

A

Most are hydrophilic

72
Q

What can the synthesis and release of biogenic amines be compared to as they have the same properties in terms of hydrophobicity?

A

synthesis & release similar to peptides

73
Q

What are many biogenic amines synthesised from?

A

Many synthesised from AAs

74
Q

The biogenic amine catecholamines are synthesised from which amino acid?

A

Tyrosine

75
Q

The biogenic amine thyroid hormone is synthesised from which amino acid?

A

Tyrosine derivative

76
Q

The biogenic amine serotonin and melatonin are synthesised from which amino acid?

A

Tryptophan

77
Q

The biogenic amine histamine is synthesised from which amino acid?

A

Histadine

78
Q

The biogenic amine acetylcholine is synthesised from which amino acid?

A

Choline & acetyl-coenzyme A

79
Q

What may the biogenic amine catecholamines act as?

A

neurotransmitters, paracrines, hormones

80
Q

Give three examples of catecholamines and what do they act as?

A

Dopamine - neurotransmitter
Noradrenalin & adrenalin – neurotransmitters, paracrines,
hormones

81
Q

The biogenic amine thyroid hormones act as?

A

hormones

82
Q

The biogenic amine serotonin acts as?

A

Seratonin - neurotransmitter

83
Q

The biogenic amine melatonin acts as?

A

Melatonin – neurotransmitter & hormone

84
Q

The biogenic amine histamine acts as?

A

Histamine – neurotransmitter & paracrine

85
Q

The biogenic amine acetylcholine acts as?

A

Acetylcholine – primary neurotransmitter at NMJ

Biomedical Physiology (19 decks)

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