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E'Pharmacology Test 1 Fall '24 > 8/28 Pharm lecture 3 > Flashcards

8/28 Pharm lecture 3 Flashcards

1
Q

What is the effector protein?

A

The protein that is activated by the G protein

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2
Q

how many second messengers are there in the Phospholipase C cascade?

A

There are 3 different second messengers, DAG, IP3, and Calcium

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3
Q

Do all g proteins elicit the same response in a cell?

A

No, different g- proteins can activate different proteins, therefore having a different overall action/effect in the cell.

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4
Q

Describe the g-protein pathway involving Phospholipase C

A
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5
Q

Describe desensitization

A

Beta arrestin binds to the OH groups attached to the end of the carboxyl terminal on the 7TM protein blocking further activity from occurring (signaling cascade can no longer occur).
Beta Arrestin drags recepto to the Clatherin coded pi on the cell membrane

The protein/receptor gets engulfed by clatherin coded pit (endocytosis)

opt 1. Drug and receptor both in pit, drug breaks off of receptor: G-protein gets moved back to the cell surface to be reused and drug is out of cell and might bind again.

opt 2. If covalent bond is too strong. Lysosome merges with the ligand and the lysosome degrades the entire drug & receptor

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6
Q

desensitization (pic) ….. explain it!

A
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7
Q

What is clatherin?

A

A protein involved in endocytosis

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8
Q

What is endocytosis?

A

The taking in of matter by a cell (cell eats something)

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9
Q

Describe Recycling of a g-protein.

A

drug breaks off of receptor: G-protein gets moved back to the cell surface to be reused.

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10
Q

What is a kinase?

A

an enzyme that attaches a phosphate group

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11
Q

What is a phosphatase?

A

An enzyme that strips a phosphate group from a protein

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12
Q

what is an example of a catalytic cell surface receptor?

A

Tyrosine Kinase (enzyme that attaches a phosphate group)

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13
Q

What is tyrosine?

A

one of our 20 amino acids

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14
Q

What are the ligands that attach to Tyrosine kinases?

A

Growth Factors: EGF (Epidermal growth factor)
Adhesion Factors: When WBC bind to the surface of a blood vessel

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15
Q

What is dimerization?

A

Two monomers coming together ( 1 is useless)

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16
Q

What does dimerization cause?

A

phosphorylation of the kinases which makes it act like a kinase enzyme

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17
Q

Describe the RTK process

A
  1. 2 ligands bind to 2 different RTK’s
  2. This makes the two monomers come together, and activates 6 ATP molecules.
  3. When they come together, they “activate” each other by becoming phosphorylated. The phosphates from the ATPs are added to the Tyrosines.
  4. It is now activated and can interact with effector proteins and create the downstream effects.
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18
Q

Where does the 6 phosphate groups come from in the RTK process when phosphate are added to Tyrosines?

A

They are pulled from 6 ATP molecules… They are attached to the 6 tyrosines

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19
Q

How are RTK’s different from G-proteins?

A

G proteins have to activate an enzyme where RTK’s are the enzyme

Once activated, it activates the Effector protein.

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20
Q

How are RTK’s the same as g-proteins?

A

They both are membrane bound, ligand activated, and eventually activate an effector protein.

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21
Q

What are voltage gated channels?

A

Pores in the cell’s surface that allow highly charged molecules to pass through the cell wall.

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22
Q

Where are voltage gated channels found within the body?

A

Excitable cells: Neurons, muscle, endocrine cells

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23
Q

Which stage is this channel in?*

A

Closed

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24
Q

Which stage is this channel in?*

A

Activated

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25
Q

Which stage is this channel in?*

A

Inactivated

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26
Q

*Which stage is this channel in?

A

Deactivated

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27
Q

What is the cycle of a voltage gated channel?

A

closed, threshold, activated, inactivated, deactivated, circles back to closed again

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28
Q

V-G channel Types are based on

A

Ion selectivity (Ca, K, Na)

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29
Q

What senses the voltage change

A

Voltage sensing amino acids

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30
Q

What activates a voltage gated channel?

A

When a resting potential gets closer and closer to the firing potential, or threshold

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31
Q

What activates a ligand-gated ion channel?

A

a ligand binding to the receptor instead of voltage. (more common)

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32
Q

What are the two subtypes of ligand-gated ion channels?

A

Inotropic (binding site and channel on same protein)
Metabotropic (ligand activates GPCR, 2nd messenger activity opens channel)

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33
Q

How does a inotropic ligand-gated channel work?

A

The same as the Voltage gated except a ligand binds to it to activate it instead of a threshold.

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34
Q

How does a metabotropic ligand-gated channel work?

A

A ligand activates a GPCR which activates the channel

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35
Q

Which ligand gated channel is more common, inotropic or metabotropic?

A

Inotropic

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36
Q

Describe how the nicotinic acetylcholine receptor works

A

neurons release 2 acetylcholine molecules

Acetylcholine molecules bind to the alpha subunits on the receptor

This opens the gate

Na+ floods into the cell

Na+ activates Ca++ channels

Ca++ floods into the cell

Ca++ activates actin myosin

muscle contracts

37
Q

Where are nicotinic acetylcholine receptors found?

A

on skeletal muscle

38
Q

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

A

Nicotinic acetylcholine

39
Q

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

A

An odorant molecule binding to a odorant receptor

40
Q

Describe how the odorant molecule binding to a odorant receptor works to help us smell.

A

(cAMP degrades pretty fast)

41
Q

What can activate a receptor inside of the cell?

A

something that is lipid soluble
a gas

42
Q

What type of cells line your blood vessels?

A

endothelial cells

43
Q

What might cause a strong shearing force on a blood vessel?

A

High blood pressure
Orthostatic blood pressure

44
Q

What is activated by a strong shearing force on a blood vessel?

A

an enzyme called nitric oxide synthase

45
Q

What does nitric oxide synthase produce?

A

Nitric oxide gas

46
Q

Where does nitric oxide gas diffuse to when it’s released?

A

all directions; its a gas. But specifically diffuses to smooth muscle that surrounds the blood vessel

47
Q

What effect does nitric oxide have on the smooth muscles around blood vessels?

A

It relaxes it, thereby opening up the blood vessel.

48
Q

What is the enzyme that turns GTP into Cyclic GMP?

A

guanylyl cyclase

49
Q

Why can steroid hormones cross the cell wall without issue?

A

It is uncharged

50
Q

What is the general gist of Absorption in pharmacokinetics?

A

It is how the drug gets to where it’s going

51
Q

What is the general gist of Distribution in pharmacokinetics?

A

It is where the drug ends up.
i.e. lipids, bone, aqueous compartments, muscle

52
Q

What is aqueous diffusion?

A

When a water soluble drug dissolves in water and get through the cell wall via aquaporins using a concentration gradient

53
Q

what is lipid diffusion?

A

When a lipid soluble drug crosses the cell wall. Lipids can cross the cell wall freely. They use concentration gradients.

54
Q

What are the different types of permeation mechanisms?

A

Aqueous diffusion (can be 20K-30K MW) Aquaporins
lipid diffusion (steroids, )
special carriers
endocytosis
exocytosis

55
Q

Can all water soluble molecules go through the aquaporin channels?

A

No.
Molecules that are too charged or too big d/t being bound to a larger protein (like albumin) they can’t go through the aquaporin.

56
Q

How do special carriers work?

A

Molecules bind to a drug and moves across barriers can be by active transport or facilitated diffusion.

57
Q

Define endocytosis and exocytosis

A

Membrane engulfment (clatherin pit eats molecules)
transports across cell membrane
Merging of vesicle with membrane (spits it out)

58
Q

What type of molecules do endocytosis and exocytosis help?

A

very large drugs

59
Q

In order to get the pharmacodynamic effect that we want, we have to take into account all of the ________

A

pharmacokinetic variables

60
Q

Dose adjustments are sometimes necessary d/t what pharmacologic parameters

A

volume of distribution
clearance

61
Q

What is volume of distribution?

A

gives an idea of How much of the drug actually go to the blood vs. how much went to other areas of the body

62
Q

What is clearance?

A

ability of the body to eliminate the drug. This is constant with drugs. (not same with elimination)

63
Q

Volume distribution is measure per

A

Liter

64
Q

Why would Vd be different for the same amount given of two different drugs.

A

Drug A might dispose of itself very quickly into the fatty tissue, where drug B sticks around in the blood a little longer. Giving Drug A a higher volume distribution than drug b. Bigger the Vd-greater amt of drug leave blood and goes to fatty tissue.

65
Q

Describe this graph

A

The volume in the blood of a certain drug at time 0, when you first give a drug, is at it’s max. Over time the volume in the blood decreases as the drug is distributed to other parts of the body

66
Q

What does a high volume distribution mean?

A

Little of the drug is left in the blood

67
Q

What is the volume of whole blood?

A

0.8L/kg 5.6L/70kg

68
Q

What is the plasma volume?

A

0.04 L/kg (half of the whole blood) 2.8L per 70kg

69
Q

What are the metric conversions?

A
70
Q

How to calculate the dose?

A

Multiply Vd by the Target concentration

71
Q

Are both Vd and Target concentrations going to be provided?

A

Yes

72
Q

Graphs for pharmacokinetics

A
73
Q

How to solve for Vd

A

Dose delivered / initial concentration in the blood

74
Q

Units for Vd

A

Liters (per 70kg)

75
Q

Describe what is going on in these pictures

A

A: you give a bolus of the drug into a closed system. the drug has no where to go so it’s concentration stays constant.

B: you give a bolus of the drug into a system with one form of elimination. This leads to a steady decrease in concentration.

C. you give a bolus of the drug into the blood, which then is distributed to other parts of the body, but isn’t eliminated here.

D. you give a bolus of the drug into the blood, it is distributed to other parts of the body, and then eventually excreted.
the initial decrease in the graph shows the distribution, the slower decrease shows the drug being eliminated.

76
Q

Clearance, for almost every drug, is going to be _______

A

constant

77
Q

What is a systemic clearance?

A

A combination of all of the modes of elimination for a drug.
CLsystemic=CLrenal+CLliver+CLother

78
Q

CLearance formula

A

CLearance = Rate of Elimination (changes) / Concentration in body at any given time (changes)

79
Q

How do you calculate the rate of elimination?

A

Multiplying the ClearanceIn f X concentration that’s in the blood

80
Q

In first order elimination, what is constant?

A

Clearance ( how many % we are eliminating)

81
Q

In zero order elimination, _________ is constant; because the receptor is _________

A

Rate of elimination; saturated

82
Q

What is zero order elimination?

A

Elimination when the body’s ability to eliminate a drug has reached it’s maximum capability d/t all of the transporters being used up. Body can only empty so fast.
Saturated all elimination mechanisms- you can only pee it out so fast.

83
Q

What is first order elmination?

A

Elimination when your body clearance percentage stays the same. (the speed stays the same)

You have a mixing bowl full of water and you have different size measuring cups to be used in a specific order from biggest to smallest. Each measuring cup is equal to 12% of the volume of water inside of the bowl. When the bowl is full you use the biggest measuring cup and dip out 12 percent. Now the biggest cup is full so you move to the next size, which dips out 12% of the remaining water. etc.

84
Q

What drugs should we associate with zero order elimination?

A

Aspirin, phenytoin, ethanol

85
Q

Vmax

A

Highest velocity you can eliminate it

86
Q

During zero order clearance- body eventually go back to _______

A

first order elimination after saturation goes down.

87
Q

Why is the rate constant in zero order elimination instead of the speed?

A

Because you have saturated your ability to eliminate that particular drug from the body any faster.

88
Q

What is a catalytic cell surface receptor?

A

A membrane bound, ligand activated active site that has an enzymatic component either directly associated with it, or the enzyme is built within itself.

E'Pharmacology Test 1 Fall '24 (5 decks)

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