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Tony's lectures > Just a phase: Metabolism of xenobiotics by the liver > Flashcards

Just a phase: Metabolism of xenobiotics by the liver Flashcards

1
Q

What are xenobitoics?

A

They are substances foreign to the host

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2
Q

Xenobiotics accumulate in different body tissues. TRUE OR FALSE?

A

TRUE

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3
Q

Many xenobiotics are non polar and lipophilic. TRUE OR FALSE?

A

TRUE

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4
Q

Xenobiotics require modifications to make them polar and water soluble and easier to excrete. TRUE OR FALSE?

A

TRUE

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5
Q

Metabolism may terminate the action of xenobiotics. TRUE OR FALSE?

A

FALSE

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6
Q

Several routes of metabolism may exist for xenobiotics. TRUE OR FALSE?

A

TRUE

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7
Q

Active absorption of molecules does not occur via transport protein. TRUE OR FALSE?

A

FALSE

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8
Q

If xenobiotics is small ion it can cross the membrane via aqueous channels. TRUE OR FALSE?

A

TRUE

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9
Q

List the factors that affect absorption

A
  • lipohilicity vs hydrophobicity
  • relative concentrations on either side of the membrane
  • The ionisation of xenobiotic
  • Particle size
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10
Q

List the factors that affect distribution

A
  • Drug lipophilicity
  • Lipoidality of tissue
  • Blood flow through tissue
  • Mass of the tissue
  • Plasma/tissue concentration gradient
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11
Q

Drug action differs between men and women. TRUE OF FALSE?

A

TRUE

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12
Q

Define metabolism

A

It is the chemical modification of xenobiotics with overall goal of ridding the body of the substance

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13
Q

Where does metabolism mainly occur?

A

In the liver

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14
Q

During first pass effect there is an extensive chemical transformation of lipophilic or heavy compounds. TRUE OR FALSE?

A

TRUE

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15
Q

List the effects the metabolite may have

A
  • May have equal activity to xenobiotic/drug
  • No or reduced activity
  • Increased activity (prodrugs)
  • Toxicity not observed in the parent molecule
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16
Q

What is elimination?

A

The main process by which the body eliminated unwanted substances

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17
Q

Name the most common routes of elimination

A
  • renal
  • biliary
  • exhalation
  • perspiration
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18
Q

What type of filtration allows drugs to pass through urine?

A

Glomerular

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19
Q

What kind of secretion provides an active carrier process for anion and cations?

A

Tubular secretion

20
Q

Volatile agents cannot be excreted via the lungs. TRUE OR FALSE?

21
Q

Where can glucuronic acid conjugate be excreted?

22
Q

Phase 1 metabolic reactions create functional groups that place xenobiotics in a correct chemical state to be acted upon at phase 2. TRUE OR FALSE?

23
Q

The majority of phase 1 reactions in hepatic microsomes employ cytochrome P450 (CYP) enzymes .TRUE OR FALSE?

24
Q

What are cytochrome P450 (cyp) enzymes?

A

They are large group of enzymes encoded for by the P450 gene superfamily

25
Q

CYPs have substrate and reaction specificity. TRUE OR FALSE?

26
Q

Which CYP metabolises 50% of therapeutic drugs?

27
Q

Genetic polymorphisms lead to individual metabolic profiles which can impact on chemotherapy of disease . TRUE OR FALSE?

28
Q

Where are reductive reactions catalysed?

A

Within the liver

29
Q

What do reductive reactions require?

30
Q

What inhibits reductive reactions?

31
Q

How does phase 2 metabolism occur?

A

It occurs through the action of a diverse group of enzymes performing a range of different reactions

32
Q

What is usually involved in conjugation in phase 2 metabolism?

A

A high energy co-factor, resulting in water soluble product which can be readily excreted

33
Q

What is the major pathway in phase 2 metabolism?

A

Major route is conjugation with a-D-glucuronic acid

34
Q

What intermediate is required in conjugation?

A

UDP-glucuronic acid

35
Q

What is the major pathway for phenols?

36
Q

What intermediate is required for sulfation?

37
Q

Sulfation is a competing pathway with glucuronidation. TRUE OR FALSE?

38
Q

Glucuronidation is predominates at high substrate. TRUE OR FALSE?

39
Q

Sulfation prdominates at low substrate. TRUE OR FALSE?

40
Q

There is relatively more PAPS in cell cytosol compared to UDPGA. TRUE OR FALSE?

41
Q

What intermediate does Methylation require?

42
Q

Acetylation requires acetyl CoA, TRUE OR FALSE?

43
Q

Where does acetylation occur?

A

In kupffer cells in the liver

44
Q

In AA conjugation, substrate is activated by the attachment of AMP. TRUE OR FALSE?

45
Q

what occurs during AA conjugation?

A
  • Substrate is activate by attachment of AMP
  • AMP is then replaced with S-CoA
  • Conjugation with endogenous AAs then occurs
46
Q

Glutathione substrates are highly electrophiic compounds. TRUE OR FALSE?

47
Q

Glutathione conjugates are excreted in bile or via

kidney. TRUE OR FALSE?

Tony's lectures (8 decks)

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