Drug Target Sites: Receptors Flashcards Preview

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Flashcards in Drug Target Sites: Receptors Deck (60):
1

In which ways do drugs act?

Therapeutically to prevent disease, relieve the symptoms and (sometimes) cure the condition

2

What is a drug?

Chemical substance/natural product which affects body function (i.e.bioactive)

3

What do drugs include?

Active agents of medicines (therapeutic agents) as well as drugs of abuse

4

What is an exogenous agent?

Manufactured outside the body

5

What is an endogenous agent?

Something the body manufactures in order to carry out a specific function e.g. hormones

6

Give an example of a hormone that's both an endogenous and exogenous agent?

Adrenaline

7

What are some examples of drugs?

Aspirin (aka acetylsalicylic acid- acetyl derivative of salicylic acid)- analgesic (pain relieving)
Diamorphine (aka diacetylmorphine, heroin)- analgesic (pain relieving) Valium (aka Diazepam)- anxiolytic (anti-anxiety)
Sildenafil (aka Viagra)- vasodilator

8

What are cells, tissues and organs controlled by?

Nervous system
Humoral agent
Local factors

9

How do drugs affect normal working cells?

By mimicking or blocking the action of the 'endogenous' agent at specific cellular targets

10

In what ways can a drug be classified?

By nature
By action
Which cell components are involved
Which of the body systems does the drug affect
How does the drug help in the disease state

11

In what way can drugs be classified in nature?

Where or how it is obtained (e.g. origin of the drug, chemical structure)

12

In what way can drugs be classified by their action?

How and where the drug acts

13

What do all drugs do?

Interact with some part of a cell to produce a response

14

In what way can drugs be classified by the components involved?

Receptors
Ion channels
Enzymes
Carrier molecules

15

In what way can drugs be classified by the system the drug effects?

E.g. cardiovascular, respiratory, immune, endocrine

16

In what ways can drugs be classified by how the drug helps in the disease state?

I.e. therapeutic/clinical effects

17

Where do drugs act on a cell?

Either on or inside the surface of cells

18

What are drugs main targets?

Receptors (MAIN)
Ion channels
Enzymes
Carrier molecules

19

What is a drug receptor?

A large (macromolecular) protein structure

20

What do drug receptors participate in?

Intracellular communication via chemical signals

21

What happens when some agents dock a receptor?

Trigger a series of events

22

What are the primary cells arranged to within the body?

Muscle
Nervous
Epithelial
Connective tissues

23

What happens upon recognition of an appropriate chemical signalling molecule (ligand)?

Receptor proteins transmit the signal into a biochemical change in the target cell

24

What do drug + receptor give?

Response

25

What are the types of signalling molecules?

Endocrine signals
Paracrine signals
Autocrine signals

26

What are endocrine signals?

Hormones produced by endocrine cells, which travel through the blood to reach all parts of the body

27

Give an example of endocrine signal

E.g. adrenaline released from the adrenals acting on the heart muscle cells

28

What are paracrine signals?

Target only cells in the vicinity of the emitting cell

29

Give an example of paracrine signalling

E.g. neurotransmitters released from neurone and acting on neighbouring muscle cell

30

What are autocrine signals?

Affect only cells that are of the same cell (type) as the emitting cell

31

Where are autocrine signals found?

Immune cells

32

Where an receptors be found?

Intracellular receptors
Cell membrane

33

What are intracellular receptors?

Only a few
Association with steroid hormones

34

Why do many receptors have to be on the cell membrane?

Many molecules are polar and can't get through membrane

35

What does cell membrane receptors involve?

Active docking site outside the cell
Endogenous transmitters or drugs interact outside the cell

36

What happens when a drug attaches to a receptor on the cell membrane?

Cell changes shape and a cascade of events occur

37

What do transmembrane receptors allow?

Communication across the cell membrane

38

What are transmembrane receptors?

Proteins that span the thickness of the plasma membrane

39

What is the structure of transmembrane receptors?

One end is outside (extracellular domain) and one end inside (intracellular domain)
7-7 proteins that span the membrane

40

Where are the active sites for transmembrane receptors?

Outside the cell

41

What can transmembrane receptors bind?

Drugs (exogenous agents) or natural (endogenous) agents e.g. Na or Ach (neurorotransmitters)

42

What are agonists?

Binds to and activates the receptor
Through series events causes a change to occur

43

What are antagonists?

Binds onto receptor
Doesn’t activate it
Tends to block it
Don’t usually see an effect
Means agonists can’t bind to receptor to stimulate and cause a change

44

What are some common features about receptors?

Proteins (glycoproteins or lipoproteins)
One or more binding sites
Activated by binding of endogenous ligand- induces a conformation (shape) change
Saturable

45

How many signals do receptors generate?

One or more (second messenger signals)

46

What properties do receptors have?

Recognition
Transduction

47

What does the fraction of total membrane receptors occupied by Ligands determine?

Size of transmembrane signal transduction
I.e. More ligand greater chance of bigger signal

48

What are drugs features that act on receptors?

Receptor modulators
Enhance/diminish transmission or receipt of a ligand generated signal
Mimic signal (agonist)
Diminish signal (antagonist)

49

What are the actions of drugs on receptors?

Allosteric agonists or antagonists enhance or block the signal by binding allosteric sites that influence signal transmission

50

Where can other drugs block signal transduction?

Within the membrane
At intercellular signal reception points

51

What is the strength a signal replayed by the receptor dependent on?

Concentration of the hormone-receptor complex

52

What is the signal strength relayed by dependent on?

Affinity of the hormone for the receptor
Concentration of the hormone
Concentration of the receptor

53

What's the equation for the drug receptor interaction?

[H] + [R] [HR]
R- receptor
H- free hormone
HR- receptor bound hormone

54

Why is Kd?

Dissociation constant for the binding of the drug to the receptor
Kd is reciprocal of the affinity constant- higher the affinity of the drug for the receptor the lower the Kd
High Kd= low affinity, fewer receptor complexes

55

How do you calculate Kd?

[Kd] = [H] x [R] / [HR]

56

What mechanisms does the recognition of a drug or hormone by a receptor require?

Non-covalent mechanisms
E.g. Covalent, ionic, hydrogen, hydrophobic, van dee Waals

57

What are most drug-receptor interactions?

Reversible
Weak chemical bonds

58

What are irreversible drug-receptor interactions?

Uncommon
Strong chemical bonds (covalent)
E.g. Aspirin, anti-tumour drugs
Usually undesirable

59

What are the major classes of receptors

Ligand gated ion channels (e.g. Acetylcholine and GABA-A receptors)
G-protein coupled receptors (e.g. Beta- adrenoceptors)
Tyrosine-kinase linked receptors (e.g. Insulin)
Ligand activated transcription factors (e.g. Thyroid and steroid hormone receptors)

60

What are the important steps of hormone initiated signal transduction?

Biosynthesis of a hormone
Storage and secretion of the hormone
Transport of the hormone to the target cell
Recognition by the hormone receptor protein
Relay and amplification of the signal that leads to defined biochemical reactions within the target cell
Removal of hormone