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Semester 2 (1st year) > Wk 21 > Flashcards

Wk 21 Flashcards

1
Q

Oxidised substances=

Reduced substances=

A

Lose electrons/ energy

Gain electrons/ energy

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2
Q

Free radical=

A

Have an unpaired electron in outer shell which makes them very unstable and reactive and want to steal an electron from another atom (but this makes that atom a free radical)

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3
Q

What is ROS?

What are ROS derived from?

What does excess ROS oxidise?

A

Reactive oxygen species (free radicals and peroxides)

Derived from metabolism of O2

oxidizes protein/ lipids/ DNA

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4
Q

How is iron related to ROS?

A

It catalyzes the reaction that forms ROS

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5
Q

Antioxidants=

What are the main antioxidants from diet?

What is the main antioxidant in the body?

A

a substance that inhibits oxidation or reactions promoted by oxygen, peroxides or free radicals

Vitamin A, C, E

Glutathione (GSH)

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6
Q

How does the liver detoxify?
(What cells remove forgein material from blood?)

Where does the liver remove waste to?

A

Cytochrome P450 enzymes convert toxic insoluble compounds into less toxic water sol metabolites that can easily be excreted

Kupffer cells

Gall bladder and kidneys

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7
Q

How does the liver clean the blood?

A

Kuppfer cells= phagocytic macrophages digest bacteria and other foreign matter in blood

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8
Q

What does the liver synthesize? (6)
Acronym to help remember

What does the liver store? (4)

Acronym to remember

A

Synthesis= Look left, go back, point up

Lipids (cholesterol, TGs, ketone bodies) 
Lipoproteins (VLDL) 
Glucose 
Bile
Proteins
Urea

Store= Give fat men (a) try

Glycogen
Fat sol vitamins (D,E,A,K) and vit B12
Metals (iron/ copper)
Triglycerides

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9
Q

What is dangerous about a vit K deficiency?

How does warfarin work?

A

Can’t ‘K’lot (clot) without vit K so increased risk of haemorrhage

it is an anticoagulant that antagonises the activity of vit K

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10
Q

What are the proteins made by the liver?

5

A

Albumin (main liver protein) and other carrier proteins

Haemostasis proteins (clotting)

Hormones and prohormones
Apolipoproteins

Enzymes (cytochrome P450)

Bile proteins

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11
Q

What is the main protein in the blood plasma?

What is a marker of liver damage?

What is the most important function of this protein?

What are 6 other cool functions of this protein?

(acronym)

A

Albumin

Serum albumin

regulate the oncotic pressure of the blood

(To brilliant Albumin, what a duuuude) 
Transport 
Buffering 
Anticoagulant 
Wound healing/ inflammation 
Antioxidant 
Detoxification
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12
Q

How does the liver breakdown/ catabolize Amino Acids?

A

First step= removal of amine group

Carbon skeleton –> ketoacid–> metabolism

Nitrogen skeleton portion -> ammonia (ammonia converted to less toxic form, urea, in liver)

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13
Q

What is transamination?

What is deamination?

A

Transfer of amino group from an amino acid to a keto acid (generates a new non-essential AA)

The removal of the amine group as ammonia (ammonia then converted to less toxic form, urea, in liver)

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14
Q

What is urea?

A

waste product formed from protein breakdown

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15
Q

What is pharmacokinetics?

A

what the body does with a drug

ADME

(picture a tic tac going through body)

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16
Q

What are xenobiotics?

Examples?

A

Forgein substances not natural to body (drugs, food additives, processed food, cosmetic products etc)

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17
Q

What is bioavailability?

A

Fraction of administered drug that reaches systemic circulation

18
Q

What is the aim of metabolism?

A

Make drug less active and more hydrophilic

19
Q

What are the 2 main classes of metabolism?

A

Phase 1: oxidation, reduction, hydrolysis of drug

Phase 2: conjugation of drug (or phase 1 product) with another molecule

20
Q

Describe phase 1 of metabolism:

A

Add functional groups such as: -OH, -COOH, -SH, -O, or NH2 to alter biological properties of drug (usually drug inactivation and makes it more water sol so can be excreted)

Also prepares drug for conjugation to functional group

21
Q

What are 3 types of enzymes in phase 1 and what do they do?

A
  • haem protein mono-oxygenases cytochrome P450 (CYP) enzymes= mixed function oxygenases
  • flavin-containing monooxygenases (FMO)
  • Epoxide hydrolases (EH)
22
Q

What enzymes do 75% of all drug metabolism?

A

CYP enzymes

23
Q

How do CYP enzymes work?

A

Drug binds to oxidised Fe CYP to form complex

NADPH donates electrons to create reactive oxygen atom and this reactive oxygen atom transferred to drug

This results in oxidised drug product plus water

24
Q

What is Phase 2 metabolism?

A

Attachment of substituent group (GST, NAT, SULT, TPMT) to make it very soluble in water
(faster than phase 1 oxidation)

25
Q

What happens to drug’s therapeutic efficacy if…

Drug is metabolised too quickly?

Too slowly?

A

Lose therapeutic efficacy

increased therapeutic efficacy or adverse drug reactions or toxicity

26
Q

What happens if drug A and drug B are metabolised by the same enzyme?

A

They compete for enzyme -> drug plasma levels are determined by which drug binds to enzyme with higher affinity (or which drug has higher conc)

27
Q

What is an example of drug A inhibiting an enzyme involved in the conversion of prodrug B to drug B (causing less formation of drug B)?

A

PPI Omeprazole inhibits CYP enzyme which is needed for antiplatelet drug to activate so taken together= increased risk of thrombus formation

28
Q

What happens when xenobiotics and drugs activate transcription and induce expression of genes encoding drug-metabolising enzymes? (2)

A

Can induce its own metab

Can induce metab destruction of other drugs

29
Q

What antibiotic induces transcription of CYP 3A4 which increases metabolism of contraceptive pill (making it ineffective)

A

Rifampicin

30
Q

What can happen if there are polymorphisms or mutations in gene encoding a metabolic enzyme?

A

Can enhance, reduce or eliminate enzyme activity (so changes in plasma levels of drug)

31
Q

What is the metabolism of opiods?

A

codeine prodrug converted by CYP2D6 into morphine

32
Q

What are the different steps of alcohol metab?

A

Ethanol absorbed in mouth, stomach and SI

Ethanol metabolised in liver by sequential hepatic oxidation
- First to acetaldehyde by alcohol dehydrogenase
Then to acetic acid by aldehyde dehydrogenase

(then to Acetyl CoA, then Fatty Acids)

33
Q

What is acetaldehyde and why is it bad to have excess?

A

It is a reactive and toxic compound

Excess= flushing, tachycardia, hyperventilation and considerable panic and distress (and nausea because CTZ activated)

34
Q

How is paracetamol metabolised…

Primarily which phase?

Normal Metabolism:

If conjugation saturated:

In overdose:

A

Predominantly in phase 2

Normal: non-toxic conjugates are added (glucuronide and sulfate conjugates) and then excretion in urine

Conjugation saturated: CYPs make toxic metabolite (NAPQI) which binds to glutathione so it can be excreted in urine

In overose: glutathione depletion so NAPQI increases -> cell death and hepatic necrosis

35
Q

What does N-acetylcysteine (NAC) do?

A

Increases glutathione synthesis in liver (so helps NAPQI get excreted in urine)

36
Q

What are the 4 stages of liver cirrhosis?

A

Normal -> Inflamed -> Fibrotic -> Cirrhotic

37
Q

High levels (outside of the hepatocytes) of what enzymes indicate significant liver cell damage:

A

Transaminase enzymes:

  • Alanine aminotransferase (ALT) [lard/ viral]
  • Aspartate aminotransferase (AST) [scotch]
38
Q

What is cholestasis?

A

Buildup of bile in liver because blockage to bile flow

39
Q

What is hyperbilirubinemia?

A

Jaundice

40
Q

What is pruritis?

A

Itchy skin due to: Increase in bile salts

41
Q

What are 4 common clinical signs of cirrhosis?

A

Palmar erythmia

Spider hemangiomas/ naevi

Ascites (fluid in abdomen)

Finger clubbing

Semester 2 (1st year) (13 decks)

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