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Pharmacy > Health and Disease > Flashcards

Health and Disease Flashcards

1
Q

define pharmacology

A

the science of drugs and how they act in biological system

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2
Q

What are the 4 main protein targets for drug action?

A
  1. receptors
  2. ion channels
  3. enzymes
  4. transporters
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3
Q

What do ion channels do?

A

they are present on cellular membranes and open in response to environmental cues, which allows the passage of channel-specific ions down a concentration gradient

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4
Q

What are the 2 ways in which drugs can affect ion channels?

A

blockers and modulators

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5
Q

What do blockers do to ion channels?

A

they block ion channels and prevent ion movement

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6
Q

What do modulators do to ion channels?

A

they don’t block the channel, but bind and increase or decrease the chance of the channel opening

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7
Q

What are the 3 ways in which drugs affect enzyme activity?

A

inhibitors, false substrates, prodrugs

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8
Q

How do inhibitors affect enzyme activity?

A

they block substrate from binding

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9
Q

How do false substrates affect enzyme activity?

A

the enzymes produce an abnormal metabolite

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10
Q

How do prodrugs affect enzyme activity?

A

drugs given to the patient are inactive, so enzymes convert them into active state

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11
Q

What do transporters do?

A

transport substances across membranes, can be against a concentration gradient- but only ONE side of membrane is open at once

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12
Q

What are the 2 ways in which drugs affect transporters?

A

inhibitors and false substrates

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13
Q

How do inhibitors affect transporters?

A

they block activity of the transporter, so it can’t transport substances across the membrane

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14
Q

How do false substrates affect transporters?

A

an abnormal compound will accumulate at the other side of the membrane

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15
Q

What are receptors?

A

proteins that typically sit on cell membrane and respond to exogenous cues and relay a signal into a cell to produce a response

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16
Q

What are the 3 ways in which a drug affects a receptor?

A

agonist, antagonist, modulator

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17
Q

How do agonists affect receptors?

A

activates the receptor when it binds

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18
Q

How do antagonists affect receptors?

A

bind to receptor, but produce NO response, and block activity of the receptor by endogenous activators

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19
Q

How do modulators affect receptors?

A

they bind to elsewhere on the receptor and increase or decrease the ability of the receptor to activate

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20
Q

define receptor

A

proteins, usually on the surface of a cell which receive and transduce signals

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21
Q

define ligand

A

something that binds, can be an agonist or antagonist

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22
Q

define agonist

A

something that binds and produces a response

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23
Q

define antagonist

A

something that binds and produces NO response

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24
Q

define second messenger

A

a molecule that relays a signal from a receptor to an effector

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25
Q

define signal transduction

A

a sequence of second messengers that elicit a biological response

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26
Q

How do receptors work?

A
  1. ligand binds to receptor
  2. causes a conformational change of the receptor protein
  3. results in a cellular effect
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27
Q

What are examples of cellular effects after a receptor is activated?

A

opening of a channel, activation of a linked enzymes. recruitment of an effector protein, intracellular transport

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28
Q

What are the 4 main families of receptor?

A
  1. ligand-gated ion channels
  2. G protein-coupled receptors
  3. Kinase-linked receptors
  4. nuclear receptors
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29
Q

How do ligand gated ion channels work?

A

when a ligand binds, it opens the channel, allowing the movement of channel-specific ions

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30
Q

What is an example of a ligand gated ion channel?

A

acetylcholine and nicotonic receptors

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31
Q

How do acetylcholine and nicotonic receptors work?

A
  1. an electrical impulse travels down the pre-synaptic neurone
  2. this triggers the release of acetylcholine
  3. acetylcholine acts on nicotinic acetylcholine receptors on the post-synaptic neurone
  4. this opens the channel, and allows sodium ion entry, which triggers an impulse in the next neurone
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32
Q

What is kinase?

A

a second messenger and an enzyme

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33
Q

What does kinase do?

A

it uses ATP to phosphorylate targets, and acts as a switch to turn target on or off and allows other 2nd messengers to bind to phosphorylated target protein

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34
Q

How do kinase-linked receptors work?

A
  1. the receptors is on the cell membrane as two halves
  2. when ligand binds to receptors it brings the two receptors halves into a dimer
  3. activates kinase activity of the receptors and a cascade and biological response
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35
Q

What is an example of a kinase-linked receptor?

A

epidermal growth factor receptor

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36
Q

How is epidermal growth factor receptor (EGFR) related to lung cancer?

A

EGFR can promote cell growth, and some patients with lung cancer may express many more EGFR receptors, so experience more growth

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37
Q

What is a G protein-coupled receptor?

A

a receptor with 7 transmembrane domains coupled to a G protein

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38
Q

How do G protein-coupled receptors work?

A

ligand binding activates the G protein bound on the intracellular surface, which interacts with an affector

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39
Q

How are G protein-coupled receptors activated?

A
  1. receptor is in resting state attached to G protein
  2. ligand binds and G protein is activated
  3. GDP is exchange for GTP by G protein
  4. GTP bound G protein interacts with the target effector, which causes a response
  5. the G protein then hydrolyses GTP to GDP and the G protein can dissociate from the effector
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40
Q

What is an example of a G protein-coupled receptor?

A

muscarinic receptors and smooth muscle contraction

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41
Q

How do muscarinic receptors work?

A
  1. muscarinic M3 G-protein coupled receptors are on intestinal smooth muscle
  2. acetylcholine activates M3 receptors
  3. the G protein is then able to bind to effector
  4. contraction of smooth muscle occurs
  5. therefore, antimuscarinics can be used to treat IBS
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42
Q

How do nuclear receptors work?

A
  1. the receptor is NOT associated with the cell membrane, but in the cyotplasm
  2. ligand enters the cell and binds to receptor in the cytoplasm
  3. ligand-receptor pair allows it to change conformation and it can move into nucleus
  4. it then binds to DNA and acts on gene expression
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43
Q

What is an example of a nuclear receptor?

A

oestrogen receptor

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44
Q

How are oestrogen receptors associated with breast cancer?

A

some patients with breast cancer may have more oestrogen receptors, so there is more growth
these receptors can be targeted by Tamoxifen

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45
Q

What is blood production controlled by?

A

multiple protein cytokines (release by WB cells) and growth factors

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46
Q

What detects blood vessel damage?

A

platelet surface receptors

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47
Q

What do platelets secrete? Why?

A

soluble factors to activate neighbouring platelets

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48
Q

What is required for a clotting cascade?

A

multiple blood proteins

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48
Q

What does thrombopoietin do?

A

regulate production of platelets

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49
Q

What does erythropoietin do?

A

regulate production of erythrocytes

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50
Q

What are the major precursors of platelets?

A

megakaryocytes

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51
Q

What kind of cells give rise to haematopoietic precursors of blood cells?

A

pluripotent stem cells

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52
Q

What creates a bruise?

A

when blood vessel endotheliums become damaged and blood leaks into surrouding tissues

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53
Q

What is the scientific name for blood clotting?

A

haemostasis

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54
Q

What 2 stages can clotting be broken down into?

A
  1. primary haemostasis
  2. secondary haemostasis
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55
Q

What happens in primary haemostasis?

A

platelets form a plug and are attracted to site of damage

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56
Q

What happens in secondary haemostasis?

A

a blood clotting mechanism is used to transform and stabilise the weak platelet plug into a clot by a fibrin network

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57
Q

What is the 1st step of platelet plug formation?

A

adhesion

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58
Q

What are the steps of adhesion in platelet plug formation?

A
  1. damage to endothelium cells exposes subendothelial tissue which is made up of collagen fibres
  2. collagen activates platelets and they adhere to these collagen fibres via an intermediate protein called von Willebrand factor (vWF)
  3. platelets binding to collagen causes a release of ADP and serotonin from their secretory vesicles, resulting in more platelet activation
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59
Q

What is the 2nd step of platelet plug formation?

A

platelet activation

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60
Q

What are the steps of platelet activation?

A
  1. release of ADP and serotonin from vesicles
  2. this causes change in shape and surface protein expression of platelets
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61
Q

What is the 3rd step of platelet plug formation?

A

platelet aggregation

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62
Q

What are the steps of platelet aggregation?

A
  1. platelets adhere to each other to form a plug
  2. synthesis and release of thromboxane A2 from arachidonic acid enhances more activation and aggregation
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63
Q

What stabilises the platelet plug?

A

fibrinogen bridges that form when receptors in the platelet surface become exposed during activation

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64
Q

What causes contraction of the plug?

A

actin and myosin

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65
Q

What do healthy endothelial cells do?

A

synthesis and release of Prostacyclin (PGI2) and nitric oxide, which both inhibit platelet activation

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66
Q

What is the scientific name for a clot?

A

a thrombus

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67
Q

What is a clot?

A

the transformation of blood into a gel consisting of fibrin polymers that occurs around the platelet plug

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68
Q

What does vessel damage activate?

A

a cascade of enzyme that results in the activation of an enzyme called thrombin

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69
Q

What does the enzyme thrombin do?

A

cleaves a protein called fibrinogen into fibrin molecules that create the fibrin network

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70
Q

Sequence of events

A

clotting factors -> prothrombin -> thrombin -> fibrinogen -> fibrin -> blood clot

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71
Q

What are the overall steps of blood clotting?

A
  1. damage to blood vessel lining triggers the release of clotting factors
  2. formation of the platelet plug and vasoconstriction limits blood flow
  3. development of the clot and fibrin strands adhere to form an insoluble clot
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72
Q

How is thrombin activated?

A

activated from prothrombin which then cleaves fibrinogen to fibrin (which is stabilised by activation of factor 8 by thrombin)

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73
Q

What are the steps in activating the clotting cascade for the extrinsic pathway?

A
  1. initiated by a tissue factor, not blood protein, on the outside of plasma membrane of cells in the sub-endothelial tissue
  2. tissue factors activates factor 7 and they both activate factor 10
  3. generates small amounts of thrombin
  4. thrombin then feeds back onto the intrinsic pathway to activate components and generate more thrombin
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74
Q

What are the steps of beginning the enzyme cascade in the intrinsic pathway of the clotting cascade?

A
  1. clotting factor 12 is activated by contact with collagen
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75
Q

What is the role of the liver in blood clotting?

A
  • produces many clotting factors
  • produces bile salts which are required for absorption of vitamin K needed for production of prothrombin
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76
Q

What does thrombin do?

A

it is an enzyme that recruits the intrinsic pathway and activates factor 5 and activates platelets

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77
Q

How does the protease activated receptor on platelets activate them?

A
  1. the enzyme thrombin binds and cleaves the thrombin receptor at a specific site on the N terminus on a platelet
  2. the cleaved N terminus can then bind and activate the receptor on the platelet
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78
Q

What are examples of clotting disorders?

A

damage to endothelium (myocardial infarction), clots (deep vein thrombosis), clotting disorders (haemophilia)

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79
Q

define pharmacology

A

the science of drugs and how they act in biological systems

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80
Q

What are the 4 main protein targets for drugs?

A
  1. receptors
  2. ion channels
  3. enzymes
  4. transporters
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81
Q

Which 2 ways do drugs affect ion channels?

A

blockers, modulators

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82
Q

How do blockers affect ion channels?

A

they block ion channels and prevent ion movement, paticularly VGNC

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83
Q

How do modulators affect ion channels?

A

they don’t block but they regulate how easily the channel opens or closes, and may need a lower or higher voltage -> so increase or decrease the chance of the channel opening

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84
Q

Which 3 ways do drugs affect enzymes?

A
  1. inhibitors
  2. false substrates
  3. prodrugs
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85
Q

How do inhibitors affect enzyme activity?

A

they block activity by binding to active site

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86
Q

How do false substrates affect enzymes?

A

they bind to the enzyme and produce an abnormal metabolite

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87
Q

How do prodrugs affect enzymes?

A

they are drugs in an inactive state and bind to enzymes to be activated

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88
Q

Which two ways do drugs affect transporters?

A

inhibitors and false substrates

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89
Q

How do inhibitors affect transporters?

A

blocks activity of the transporter so it can’t move substances across the membrane

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90
Q

How do false substrates affect transporters?

A

transporter thinks it is a different substrate, so an abnormal compound accumulates

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91
Q

What are the 3 ways in which drugs can affect a receptor?

A

agonist, antagonist, modulator

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92
Q

How do agonists affect receptors?

A

they bind to and activate the receptor

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93
Q

How do antagonists affect receptors?

A

they bind to the receptor and block activity by other activators -> do NOT activate it though

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94
Q

How do modulators affect receptors?

A

they bind elsewhere on the receptor and increase or decrease the ability of the receptor to activate

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95
Q

define receptor

A

proteins, usually on the surface of a cell which receive and transduce signals

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96
Q

define ligand

A

something that binds

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97
Q

define agonist

A

something that binds and induces a response

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98
Q

define antagonist

A

something that binds and produces NO response

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99
Q

define second messenger

A

a relay signal from a receptor to effector

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100
Q

define signal transduction

A

a sequence of second messengers that elicit a biological response

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101
Q

What are the steps of a basic ligand-receptor interaction?

A
  1. ligand binds to receptor
  2. this causes a conformational change of the receptor protein
  3. this results in a cellular effect e.g. opening of a channel
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102
Q

What are the 4 main types of receptor?

A
  1. ligand-gated ion channels
  2. G protein-coupled receptors
  3. kinase-linked receptors
  4. nuclear receptors
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103
Q

How do ligand-gated ion channels work?

A

substance binds to it and opens the channel, allowing movement of channel-specific ions

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104
Q

What is an example of a ligand-gated ion channel?

A

acetylcholine and nicotinic receptors

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105
Q

What is the function of kinase?

A

an enzyme and second messenger that uses ATP to add a phosphate to targets, activating them

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106
Q

How do kinase-linked receptors work?

A

the receptor is on the cell membrane as two halves and binding bring them together, which activates kinase activity and causes a cascade

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107
Q

What is an example of a kinase-linked receptor?

A

epidermal growth factor receptor and lung cancer -> EGFR promotes cell growth, so patients with more of these proteins experience mroe growth

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108
Q

How do G protein-coupled receptors work?

A

they are receptors with 7 transmembrane domains coupled to a g protein and ligand binding activates the G protein which interacts with an effector

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109
Q

What is an example of G protein-coupled receptors?

A

muscarinic receptors and smooth muscle contraction

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110
Q

How do nuclear receptors work?

A

the receptor is NOT on the cell membrane, but in the cytoplasm -> ligand-receptor pair allows it to change conformation and it can move into nucleus where it binds to DNA and acts on gene expression

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111
Q

What is an example of nuclear receptors?

A

oestrogen receptor and breast cancer

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112
Q

Which 2 factors determine a receptor response?

A

affinity and efficacy

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113
Q

define affinity

A

how well a drug binds to a receptor

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114
Q

define efficacy

A

how well a drug activates a receptor

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115
Q

How are receptor responses measured?

A

concentration-response curves

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116
Q

How are concentration-response curves plotted?

A

a chosen response is recorded e.g muscle contraction and the recorded response is plotted against LOG agonist concentration

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117
Q

describe and explain the concentration-response curve

A
  1. initial low concentration gives limited response as low receptor binding
  2. more agonist is added and there is more binding
  3. a plateau is reached as we either have full receptor occupancy or we have added all agonist and can’t get a higher biological response
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118
Q

define Emax

A

the maximum response produced by an agonist

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119
Q

define EC50

A

the concentration of agonist needed to give 50% of Emax

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120
Q

How can we compare agonist drugs in the same biological system?

A

compare the profile of their concentration-response curves, Emax and EC50 values

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121
Q

What does it mean if another agonist has a curve to the right?

A

it has a higher EC50, so a higher concentration of agonist is needed to give the same response, so the agonist is LESS POTENT that the other

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122
Q

What do different EC50 values indicate?

A

different potencies for the receptor

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123
Q

define partial agonist

A

an agonist that binds to a receptor but does not produce a FULL response - either poor efficacy or affinity

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124
Q

What does the concentration-response curve look like for a partial agonist?

A

it will have an Emax below a full agonist and different EC50

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125
Q

define inverse agonist

A

an agonist that reduces a biological response below basal levels

126
Q

What does the concentration response-curve look like for an inverse agonist?

A

Emax is below basal level

127
Q

What is an example of an inverse agonist drug?

A

drugs that reduce heart muscle contraction -> heart has basal level of activity without any agonist present

128
Q

define biased agonism

A

when different agonists bind to the same effector but activate different second messengers and create a different reponse

129
Q

What is an example of biased agonism?

A

G protein-coupled receptors can signal through a G protein or arrestin

130
Q

define arrestin

A

proteins that regulate the signalling of G protein-coupled receptors

131
Q

define balanced agonist

A

an agonist that activates both pathways to the same level

132
Q

What are the 2 types of competitive antagonist?

A

reversible or irreversible

133
Q

define competitive antagonist

A

an antagonist competes with agonists for the same receptor binding site

134
Q

How do reversible antagonists work?

A

increasing agonist concentration can outcompete antagonist

135
Q

How do irreversible antagonists work?

A

they permanently bind to receptors, so no amount of agonist can dislodge it

136
Q

How do reversible antagonists affect concentration-response curves of an agonist?

A

curve to the right but still can reach Emax, as a higher concentration of agonist A is needed to give the same response

137
Q

How do reversible antagonists affect Emax and EC50?

A

Emax of the agonist stays the same, but EC50 of agonist increases

138
Q

How do irreversible antagonists affect concentration-response curves of an agonist?

A

curve will be lower and to the right

139
Q

How does an irreversible antagonist affect Emax and EC50 of an agonist?

A

Emax of agonist decreases, EC50 of agonist increase

140
Q

How do we measure antagonism?

A

using the Schild plot and PA2

141
Q

define Schild plot

A

a way to determine the nature and potency of an antagonist

142
Q

What are the axes on a Schild plot?

A

X axis -> log (concentration of antagonist)
Y axis -> log (dose ratio -1)

143
Q

What is the equation for dose ratio?

A

EC50 of agonist with antagonist / EC50 of agonist without antagonist

144
Q

How do you determine the pA2 value?

A

pA2 vaule is where the line on the Schild plot intersects the X-axis (remember it is negative log of concentration)

145
Q

What does pA2 measure?

A

antagonist potency

146
Q

What is the pA2 equation?

A

pA2 = log(dose ratio -1) - log[antagonist]

147
Q

What does a higher pA2 value indicate?

A

a more potent antagonist

148
Q

What is indicated if two antagonists give the same pA2 value?

A

they act through the same receptor

149
Q

Where do agonists and competitive antagonists bind on a receptor?

A

the orthosteric site

150
Q

What is the allosteric site and its function?

A

another site on the receptor -> other molecules can bind here and modify the effects of an agonist

151
Q

define affinity modulation

A

the process of altering how well the agonist binds to the orthosteric site

152
Q

define efficacy modulation

A

the process of altering how well the agonist activates the receptor

153
Q

define affinity allosteric modulator

A

a ligand that binds to a receptor and alters how well the AGONIST binds to the receptor at the orthosteric site

154
Q

What do positive affinity allosteric modulators do?

A

increase how well an agonist binds to the orthosteric site, and decreases the concentration needed for the same reponse

155
Q

What do negative affinity allosteric modulators do?

A

decrease how well an agonist binds to the orthosteric site, and increase concentration needed for the same response

156
Q

define efficacy allosteric modulator

A

a ligand that binds to a receptor and alters how well the agonist activates the receptor -> the full response of the agonist will be increased or decreased

157
Q

define allosteric agonist

A

an allosteric ligand that binds to a receptor and can cause a response on its own without need for an agonist

158
Q

What type of cells are neurones?

A

postmitotic

159
Q

define postmitotic

A

cells that are fully differentiated and unable to divide

160
Q

define soma

A

the cell body of a neurone, an expanded area of cytoplasm where nucleus and organelles are found

161
Q

Which organelle do neurones NOT have?

A

centrioles -> important in cell division, so don’t need them

162
Q

What is the structure and function of the myelin sheath?

A

made up of Schwann cells and they insulate the axon

163
Q

What are the 4 shape classes of neurones?

A

multipolar, bipolar, unpolar, anaxonic

164
Q

What are the 3 classes of neurones?

A

afferent, efferent, interneurone

165
Q

define afferent neurone

A

transmits signal from receptors to CNS

166
Q

define efferent neurone

A

transmits signal from CNS to effectors

167
Q

define interneurone

A

transmits signal from afferent to efferent neurones

168
Q

What is a resting membrane potential (RMP)?

A

an electrical charge across the plasma membrane, with the interior of the cells negative compared to exterior

169
Q

define chemical gradient

A

gradient based on concentration

170
Q

define electrical gradient

A

gradient based on charge

171
Q

What are the 2 types of movement across the plasma membrane involving proteins?

A

facilitated diffusion and active transporters (pumps)

172
Q

define facilitated diffusion

A

when ions diffuse down their concentration gradient and the channels are selectively permeable to different ions

173
Q

define active transport

A

when pumps move ions against their concentration gradient and create a concentration gradient across the membrane

174
Q

How do Na+ and K+ pumps maintain excitability?

A

active transporters exchange 2K+ in for every 3NA+ out

175
Q

What is the resting membrane potential in most neurones?

A

-70mV

176
Q

Which equation is used to calculate the equilibrium potential for an ion?

A

the Nernst equation

177
Q

give the Nernst equation

A

E ion = RT / zF x log [ion]outside / [ion]inside

178
Q

Which other equation is used to calculate the resting membrane potential?

A

Goldman equation

179
Q

define action potential

A

a brief change in the voltage across a membrane due to the flow of ions into and out of the neurone

180
Q

What does the ‘all or nothing law’ describe?

A

if a stimulus is strong enough, an action potential occurs, which is always a full response i.e. can’t be strong or weak

181
Q

What are the 5 phases of action potentials?

A
  1. hypopolarisation
  2. depolarisation
  3. overshoot
  4. repolarisation
  5. hyperpolarisation/undershoot
182
Q

define hypOpolarisation

A

the initial increase of the membrane potential to the value of threshold potential

183
Q

define depolarisation

A

the potential moving from the RMP to less negative values

184
Q

define overshoot

A

the peak of the action potential being reached at about +40mV

185
Q

define repolarisation

A

the potential moving back to the RMP (-70mV)

186
Q

define hyperpolarisation/undershoot

A

the potential moves away from the RMP in a MORE negative direction, but the RMP is eventually restored due to K leak channel and sodium-potassium pump

187
Q

action potential stage 1

A

membrane is at resting potential and VGNC and VGKCs remain closed

188
Q

action potential stage 2

A

a stimulus causes depolarisation the threshold potential and VGNCs open

189
Q

action potential stage 3

A

Na+ ions flow in and the membrane rapidly depolarises and more VG sodium ion channels open but VGKCs remain closed

190
Q

action potential stage 4

A

VG sodium ion channels are inactivated and Na+ entry slows

191
Q

action potential stage 5

A

VGKCs open and K+ begin to flow out, beginning repolarisation

192
Q

action potential stage 6

A

VGNC channels fully close and VGKC remain open to give delayed hyperpolarisation -> eventually resting potential is restored

193
Q

What are the properties of VGNCs?

A
  1. open rapidly with depolarisation at around -55mV
  2. moving away from -55mV causes inactivation
  3. inactivated channels are blocked during continued depolarisation
  4. inactivated channels move to a closed state during repolarisation
194
Q

What are the properties of VGKCs?

A
  1. K+ channels slowly open during depolarisation at about +30mV
  2. they close slowly on repolarisation
195
Q

What are the 2 classes of refractory period?

A

absolute refractory period, relative refractory period

196
Q

What happens during the absolute refractory period?

A

action potentials cannot be generated as VGNCs are inactivated and can’t be activated again until the membrane is repolarised and resting state is restored

197
Q

When does the refractory period occur?

A

from the start of an action potential to the point that voltage first returns to RMP

198
Q

What happens during the relative refractory period?

A

the membrane potential is hyperpolarised by VGKCs and action potentials CAN be generated if the stimulus is strong enough to overcome hyperpolarisation and reach threshold

199
Q

What is action potential propagation?

A

the process by which an action potential travels across a neurone

200
Q

How does action potential propagation work (local currents)?

A
  1. stimulation at point A exceeds threshold
  2. local currents spread along axon and exceed threshold
  3. this opens VGNC and generate AP at point B
  4. VGNC inactivation occurs and open VGKC prevent back-propagation
201
Q

What 2 factors does the velocity of action potential propagation depend on?

A
  1. axon diameter
  2. myelination
202
Q

How does axon diameter affect action potential propagation velocity?

A

the larger the diameter, the faster the propagation as there is more space for ions to travel

203
Q

define saltatory conduction

A

the propagation of action potentials along myelinated axons from one node of Ranvier to the next, increasing velocity

204
Q

What causes Guillain-Barre syndrome?

A

the destruction of Schwann cells in the peripheral nervous system

205
Q

What causes multiple sclerosis (MS)?

A

a loss of oligodendrocytes in the brain and spinal column

206
Q

What are the 2 types of graded potential?

A

excitatory and inhibitory

207
Q

What do inhibitory graded potentials do?

A

take the membrane further away from the threshold potential

208
Q

What are the 4 types of excitatory graded potentials?

A
  1. temporal summation
  2. spatial summation
  3. no summation
  4. spatial summation of EPSPs and IPSPs
209
Q

define temporal summation

A

2 excitatory stimuli close in time causes EPSPs to add together

210
Q

define spatial summation

A

2 simultaneous stimuli at different locations cause EPSPs to add together

211
Q

define no summation

A

2 stimuli separated in time cause EPSPs that do NOT add together

212
Q

define spatial summation of EPSPs and IPSPs

A

changes in membrane potential that cancel each other out

213
Q

define synapse

A

the point at which an electrical signal moves from one nerve cell to another

214
Q

What are the 2 types of synapse?

A

electrical and chemical

215
Q

What is the structure of an electrical synapse?

A

the pre and post-synaptic neurones are directly connected by gap junctions

216
Q

What is the structure of an chemical synapse?

A

the pre and post-synaptic neurones are physically separated by the synaptic cleft and chemical transmitter from pre-synaptic neurone binds to receptors on post-synaptic neurone

217
Q

What are gap junctions?

A

channels formed by connexons in both cell membranes and allow direct passage of ions and small molecules through the channels

218
Q

What are the features of chemical synapses?

A
  1. synaptic vesicles filled with neurotransmitter on the inside of the presynaptic neurone
  2. voltage-gated calcium ion channels in presynaptic neurone
  3. neurotransmitter receptors on postsynaptic neurone
219
Q

What are the 3 types of synapse in the CNS?

A

axo-dendritic, axo-somatic, axo-axonal

220
Q

define axo-dendritic synapse

A

an axon synapsing onto a dendrite

221
Q

define axo-somatic synapse

A

an axon synapsing onto a cell body

222
Q

define axo-axonal synapse

A

an axon synapsing onto another axon or axon terminal

223
Q

define neurotransmitter

A

a chemical messenger that is released from a pre-synaptic neurone

224
Q

What are the sequence of events involved at a chemical synapse?

A
  1. neurotransmitter is synthesised and stored in vesicles
  2. AP arrives at presynaptic terminal
  3. AP depolarises the terminal and VGCC opem
  4. Ca2+ enter and trigger exocytosis
  5. transmitter diffuses down synaptic cleft and binds to receptors
  6. ion flow causes postsynaptic response
  7. transmitter is removed by enzyme breakdown or reuptake
  8. the vesicle is retrieved from the terminal membrane
225
Q

What are the 4 key criteria for a substance being a neurotransmitter?

A
  1. substance must be present within the presynaptic neurone
  2. substance must be released in response to presynaptic depolarisation by an AP
  3. specific receptors for the substance must be present on the postsynaptic cell
  4. there must be a mechanism for removal and/or breakdown
226
Q

What are the 2 types of neurotransmitter receptor?

A

ionitropic receptor, metabotropic receptor

227
Q

What is an ionotropic receptor?

A

a ligand (transmitter) gated ion channel that opens to allow passage of ions through membrane in response to binding

228
Q

What is a metabotropic receptor?

A

a g protein-coupled receptors -> binding activates g-protein which activates second messenger which can directly affect ion channels on membrane

229
Q

What is a neuromuscular junction?

A

the synapse between a motor neurone and skeletal muscle

230
Q

What is a neuromuscular junction also known as?

A

a motor endplate

231
Q

Which neurotransmitter and receptor are used at neuromuscular junctions?

A

acetylcholine and nicotinic receptors

232
Q

What type of receptor in the nicotinic acetylcholine receptor?

A

ionotropic or neurotransmitter-gated ion channel

233
Q

How is acetylcholine synthesised?

A

in the presynaptic terminals by the enzyme choline acetyltransferase

234
Q

How is acetylcholine broken down?

A

by acetylcholinesterase into acetate and choline

235
Q

What is the main excitatory transmitter in the CNS?

A

glutamate

236
Q

What type of receptor does glutamate activate?

A

both ionotropic and metabotropic receptors

237
Q

What is the main inhibitory transmitter in the CNS?

A

GABA (G-aminobutyric acid)

238
Q

What type of receptor does GABA work on?

A

a small family of ionotropic and metabotropic receptors

239
Q

What type of potential does glutamate generate?

A

an excitatory postsynaptic potential (EPSP)

240
Q

What type of potential does GABA generate?

A

an inhibitory postsynaptic potential (IPSP)

241
Q

What do IPSPs do?

A

make a neurone less likely to generate an action potential

242
Q

define gastrointestinal system

A

a network of organs and specialised cells that enable you to transform food into the energy and nutrients required for life

243
Q

Which organs is the GI tract made up of?

A

mouth, oesophagus, stomach, small intestine, large intestine, anus

244
Q

Name the accessory organs

A

salivary glands, liver, gallbladder, pancreas

245
Q

define accessory organ

A

an organ that plays a role in the function of the GI tract but is not part of it

246
Q

define mesentery

A

a membranous tissue that surrounds the organs of the GI tract

247
Q

What is the function of the mesentery?

A
  • holds intestines in place
  • has lots of blood vessels and lymphatics for absorption and immunity
248
Q

What prevents food travelling to the lungs?

A

the pharynx and epiglottis

249
Q

What is the function of the oesophagus?

A

to transport food bolus to the stomach

250
Q

What are the main functions of the stomach?

A
  • mix food
  • digest protein
  • emulsify fat
251
Q

How many layers is the stomach wall made up of?

A

4

252
Q

Which cells is the stomach acid produced by?

A

parietal cells

253
Q

Which 3 sections is the small intestine divided into?

A

duodenum, jejunum, ileum

254
Q

What is the function of the small intestine?

A

primary site of absorption

255
Q

What increases the surface area of the small intestine?

A

finger-like projections called villi that contain microvilli with epithelial cells on surface

256
Q

Which 3 sections is the small intestine divided into?

A

ascending colon, transverse colon, descending colon

257
Q

What is the function of the large intestine?

A
  • role in conservation of water and ions
  • storage of faecal matter
  • crypts that are involved in lysosome secretion
258
Q

How many sets of salivary glands do humans have?

A

3

259
Q

What is the function of saliva?

A
  • contains some digestive enzymes
  • lubricates food with mucus
260
Q

What is the function of the liver in digestion?

A
  • produces bile and involved in excretion
  • bile is needed for emulsification of fats
261
Q

What is the function of the gallbladder?

A
  • collects secretions from liver
  • delivers bile to duodenum
262
Q

What is the function of the pancreas?

A
  • makes enzymes to digest proteins, fats, carbohydrates
  • produces insulin and glucagon from islets of Langerhans
263
Q

What are the 4 functions of the GI system?

A
  1. ingestion
  2. secretion
  3. movement
  4. digestion
264
Q

define ingestion

A

the process of taking in food or drink through the mouth

265
Q

define secretion

A

the release of substances that contribute to digestion

266
Q

What are the 2 main types of movement in the GI system?

A

segmentation and peristalsis

267
Q

define segmentation

A

‘squishing’ of substances backwards and forwards to help move them

268
Q

define peristalsis

A

coordinated movement with contraction and relaxation of intestine

269
Q

define digestion

A

breakdown of food into smaller components that can be absorbed into the bloodstream

270
Q

What are the 2 types of digestion?

A

mechanical and chemical

271
Q

define absorption

A

the process through which nutrients, water and electrolytes enter the blood (through villi and microvilli)

272
Q

define excretion

A

the process by which metabolic waste is eliminated from the body

273
Q

Which 2 main parts is the nervous system divided into?

A

the central and peripheral nervous systems

274
Q

What is the central nervous system made up of?

A

the brain and spinal cord

275
Q

define periphery

A

the area that is away from the centre of the body

276
Q

define afferent neurone

A

a neurone that transmits an action potential from the periphery to the CNS

277
Q

define efferent neurone

A

a neurone that transmits an action potential from the CNS to the periphery

278
Q

define vertebrae

A

a stack of bones that surround the spinal cord

279
Q

What are the 4 sections of spinal nerves that receive inputs and send outputs?

A

cervical, thoracic, lumbar, sacral

280
Q

How do sensory inputs enter the CNS?

A

through the dorsal root into the spinal cord

281
Q

What is the dorsal root ganglion?

A

where the cell bodies of axons are just outside the vertebrae in the spinal cord

282
Q

What type of neurone are most sensory neurones?

A

unipolar -> have a cell body and one long axon

283
Q

What is the simplest example of a connection between sensory neurone input and output back to the periphery?

A

the monosynaptic reflex

284
Q

define monosynaptic

A

there is ONE synapse between the presynaptic and postsynaptic neurone

285
Q

What type of neurone are most motor neurones?

A

multipolar

286
Q

define reflex

A

when input is received by the periphery and the body provides output back to the periphery without any conscious thought

287
Q

What do proprioceptors do?

A

sense position and movement

288
Q

How does the knee jerk reflex work?

A
  1. tap the tendon attached to the quadriceps
  2. the tendon gets pulled, which stretches the quadriceps
  3. this is sensed by the muscle spindle fibres (proprioceptors)
  4. generates action potential
  5. action potential goes through dorsal root to spinal cord
  6. neurotransmitter is released in spinal cord
  7. this causes an action potential in a motor neurone, which causes the quadriceps to contract
289
Q

What is the pathway of a reflex arc?

A
  1. receptor gives input to integrative centre
  2. integrative centre gives output to effector
290
Q

What is USUALLY the integrative centre?

A

the spinal cord

291
Q

How do sensory neurones vary?

A

by thickness and myelination

292
Q

What does the extent of myelination determine?

A

the speed of an action potential

293
Q

define ascending pathway

A

neuronal input travelling from the spinal cord to the brain

294
Q

give an example of an ascending pathway in proprioception

A
  1. action potential comes into dorsal root
  2. goes up the spinal cord to a synapse at the brain stem (medulla)
  3. action potential crosses to the other side of the body
  4. it reaches another synapse in the middle of the brain called the thalamus
  5. eventually reaches the somatosensory cortex
295
Q

define descending pathway

A

information going from the brain to the spinal cord

296
Q

Where does all input from the periphery to the CNS BELOW the neck go to?

A

the spinal cord

297
Q

Where does all input from the periphery to the CNS go to if ABOVE the neck?

A

the cranial nerves

298
Q

define glial cell

A

a cell that is specialised to help neurones function but are NOT neurones

299
Q

What are 2 examples of glial cells?

A

oligodendrocytes and astrocytes

300
Q

What do oligodendrocytes do?

A

produce myelin -> there are different glial cells that do this in the peripheral nervous system called Schwann cells

301
Q

What does astrocytes do?

A

act as a buffer to equalise concentrations of k+ ions -> there may be high concentrations of K+ ions if axons are generating many action potentials, so astrocytes ‘suck them up’ and move them to other parts of the brain

302
Q

define the meninges

A

the 3 layers of membranes that cover and protect the brain and spinal cord

303
Q

What is the outer membrane called?

A

dura mater

304
Q

What is the inner membrane called?

A

the pia mater

305
Q

What is the space between the inner and outer membranes called?

A

the sub arachnoid space

306
Q

What is the sub arachnoid space filled with?

A

cerebrospinal fluid

307
Q

What is the function of the choroid plexus?

A

it is a gland in the middle of the brain that produces cerebrospinal fluid

308
Q

What does the cerebrospinal fluid contain?

A

salt and sugar -> high concentrations of Na+ and low K+ -> glucose and oxygen

309
Q

What is the blood-brain barrier?

A

a semipermeable membrane separating the blood from the cerebrospinal fluid and brain

310
Q

What is the structure of the blood-brain barrier?

A

tight junctions between the endothelial cells and blood vessel wall (tight junction is a seal between two cells that prevents leakage of content)

311
Q

What does the blood-brain barrier do?

A

prevents substances leaking out of the blood vessels into the brain, including blood borne viruses and bacteria

312
Q

Which cells acts as immune cells in the brain?

A

microglia

313
Q
A

Pharmacy (6 decks)

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