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Physiology > W2 - Types of Signalling Molecules > Flashcards

W2 - Types of Signalling Molecules Flashcards

1
Q

Biogenic amines are usually/always hydrophobic/philic?

A

Usually hydrophilic

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2
Q

Peptides are usually/always hydrophobic/philic?

A

Always hydrophilic

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3
Q

Steroid are usually/always hydrophobic/philic?

A

Always hydrophobic

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4
Q

Lipids are usually/always hydrophobic/philic?

A

Always hydrophobic

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5
Q

Signalling gases are usually/always hydrophobic/philic?

A

Always hydrophilic

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6
Q

Thyroid hormones are usually/always hydrophobic/philic?

A

Always hydrophobic

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7
Q

Purines are usually/always hydrophobic/philic?

A

Always hydrophilic

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8
Q

Where are peptide signalling molecules translated and PTMed?

A

rER and then GA

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9
Q

Which peptides are released immediately after synthesis and which are stored for long periods of time (released when required)?

A

Immediately - cytokines, Stored - peptide NTM and hormones

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10
Q

What happens when a peptide signal binds to an ionotropic/metabotropic receptor?

A

Ionotropic - influx of ions, metabotropic - changes an enzyme’s activity within cell

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11
Q

What enzymes degrade peptide signals to stop the signal, decreasing it’s half life?

A

Protease and peptidases

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12
Q

Some peptide signals such as glycoproteins are degraded much slower (hours), in this case, how must a signal be sustained?

A

Continuous synthesis of the signal by the cell

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13
Q

Androgens and estrogens are two classes of steroid hormones, what are the other 3?

A

Progestins, glucocorticoids and mineralocorticoids

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14
Q

Which organelles are steroid hormones synthesised in?

A

Mitochondria and sER

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15
Q

Why cannot steroid hormones be stored within vesicles or cells?

A

They are lipophilic and so are soluble in the
plasma membrane

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16
Q

What does steroid hormones being lipophilic mean about when they are synthesised in relation to their secretion?

A

They must be synthesised immediately prior to secretion

17
Q

Globulin and albumin carrier proteins are needed for transport of steroid hormones to their target sites, why?

A

They are hydrophobic and so aren’t soluble in the extracellular aqueous fluid

18
Q

What is the equation for the laws of mass action and mass action equilibriums?

A

M+C <–> MC

19
Q

In terms of M+C <–> MC, what happens where the conc of the signal is highest and where is is lowest?

A

Highest - M binds C and is then moved away in the circulatory system to Lowest - M unbinds from MC (M can then interact with target)

20
Q

Which receptor types do steroid signals usually bind?

A

Nuclear I receptors on surface of nucleus or nuclear II receptors inside nucleus

21
Q

When a steroid hormone is bound to a receptor, what is it called?

A

Ligand dependent transcription factor

22
Q

How do ligand dependent transcription factors regulate gene expression?

A

Bind to DNA and interact with RNA polymerase

23
Q

What are 3 examples are gas molecules that act in cell-cell communication?

A

CO, HS and NO

24
Q

Gas molecules interact with intracellular proteins but are hydrophilic, how is this possible?

A

They are very small and so can readily diffuse through the membrane

25
Q

What enzyme synthesises NO from arginine?

A

NO synthase

26
Q

Why can NO only act in autocrine/paracrine signalling?

A

It has a very short half life of 2-30secs

27
Q

Which 2 systems can NO work in?

A

In the immune system and cardiovascular system

28
Q

Steps of NO as a vasodilator (lowering bp) (3 steps)

A
  1. NO is synthesised by NOS in vascular endo cells and it diffuses into vascular smooth muscle cells, binding to soluble guanylyl cyclase 2. GTP –> cGMP 3. cGMP activates PKG to relax smooth muscle layer around blood vessels
29
Q

What are the purines?

A

Adenine and Guanine

30
Q

What limits the action of prostaglandins and purines to autocrine/paracrine action?

A

Their metabolism

31
Q

Which enzymes are prostaglandins and purines susceptible to? (for hydrolysis)

A

Prostaglandins - short chain alcohol dehydrogenase (SCAD) and 15-hydroxyprostaglandin dehydrogenase (PGDH), Purines - ectonucleotidases

32
Q

What do ectonucleotidases do?

A

Remove phosphates from tri/di/mono phosphates on nucleotides

33
Q

What do purine signals bind to to activate transmembrane signalling?

A

Purinergic receptors

34
Q

What metabotropic and ionotropic receptors do adenosine and ATP act on?

A

P1 and P2Y GPCRs (met) and P2X (ion)

Physiology (14 decks)

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