Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

liver & friends lectures > liver detoxification > Flashcards

liver detoxification Flashcards

1
Q

define xenobiotics

A

foreign chemical substance not normally found or produced in the body which cannot be used for energy requirements

eg drugs

can be absorbed across lungs or skin OR ingested

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how are xenobiotics excreted

A

bile , urine , sweat and breath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

properties of pharmacologically active compounds

A
  • lipophilic
  • non-ionised at pH 7.4
  • bound to plasma proteins to be transported in blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

lipophilic definition

A

able to dissolve in lipids/fats

to be able to pass through plasma membranes to reach metabolising
enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 2 types of enzymes involved in metabolic reactions

A
  • microsomal enzymes
  • non-microsomal enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

define microsomes

A

fragments of endoplasmic reticulum with attached ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where are microsomal enzymes found

A

in microsomes on smooth endoplasmic reticulum

mostly found in liver hepatocytes but can be found in the kidneys & lungs too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where are non-microsomal enzymes found

A

anywhere but microsomes

located in the cytoplasm & mitochondria of hepatocytes in the liver but also in other tissue too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

which type of reactions do microsomal enzymes carry out

A

mainly Phase I reactions, but can do phase 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what affects the activity of microsomal enzymes

A

drugs, food, age, bacteria & alcohol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

which type of reactions do non-microsomal enzymes carry out

A

mainly Phase II reactions, but can do phase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

are non microsomal enzymes inducible

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

which reactions are non-microsomal enzymes involved in

A

all conjugation reactions except GLUCURONIDATION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

which reactions are microsomal enzymes involved in

A

oxidative,reductive & hydrolytic reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how are drugs usually excreted

A

most are excreted by the kidneys

but lipophilic drugs are not effectively
removed

as they are passively absorbed

because they can diffuse through cell membranes easily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

aim of drug metabolism

A

to make the drugs more polar so they cannot get across membranes and thus are easily excreted

17
Q

where does drug metabolism mainly occur

A

liver

18
Q

what are the 2 pathways for drug metabolism

A

phase 1 reaction
phase 2 reaction

19
Q

what is phase 1 liver detoxification

A

the first line of defense against toxins. It consists of a group of enzymes known as the cytochrome P450 family

20
Q

what is phase 2 liver detoxification pathway

A

neutralizes the byproducts of Phase I liver detoxification and other remaining toxins.

by making the toxins water-soluble.

so they can be excreted from the body - conjugation

21
Q

what is the aim of phase 1 for lipophilic drugs

A

to make the drug more hydrophilic so that it can be excreted by the kidneys
- it does this by adding a hydroxyl group to the drug

Introduces reactive group to drug - attack point for conjugation

22
Q

why do hydrophilic molecules not reach the metabolising enzymes

A

because they are excreted easily

23
Q

what are the 4 methods of oxidation

A
  • Hydroxylation (add -OH)
  • Dealkylation (remove -CH side chains)
  • Deamination (remove -NH)
  • Hydrogen removal
24
Q

what happens in reduction

A

hydrogen is added
so unsaturated bonds become saturated

25
Q

what is functionalisation

A
  • Introduces reactive group to drug
  • Includes adding or exposing; -OH,-SH,-NH2,-COOH
  • The product of the reaction is usually more reactive
  • There is a small increase in HYDROPHILICITY
26
Q

how do cytochrome P450 enzymes work

A

Uses heme group (Fe2+) to oxidise substances
the products are more water soluble

27
Q

how to name cytochrome P450 enzymes

A

1st number = the family the enzyme belongs to

Letter= indicates subfamily

2nd number= individual genes involved

28
Q

what is cytochrome P450 reductase

A

the enzyme required to transfer electrons from NADPH to CY P450

Contains flavoprotein which in turn consists of; Flavin adenine dinucleotide (FAD) & flavin mononucelotide (FMN)

29
Q

what does FAD do

A

accepts electrons from NADPH

30
Q

what does FMN do

A

electron donor to CYP’s

31
Q

what can phase I reactions do

A
  • Inactivate drugs
  • Further activate drug
  • Activate drug from pro-drug (inactive form of drug)
  • Make a drug into a reactive intermediate (could be carcinogenic or toxic)
32
Q

what happens in phase II reactions

A

“conjugation reaction”:
- Attachment of substituent groups (endogenous (from the body) molecules)

usually forms inactive products

33
Q

what are phase II reactions catalysed by

A

transferases

34
Q

where do phase II reactions occur

A

mainly in liver, but can occur in other tissues like the lungs & kidneys

35
Q

what is a glucuronidation reaction

A
  • Adding a glucuronic acid group
  • Increases hydrophilicity
  • substances produced from this are glucoronides
  • process forms covalent bonds
36
Q

enzyme for glucoronidation reaction

A

glucuronosyltransferase/ UGT - microsomal

37
Q

what is Uridine diphospho-glucuronic acid (UDPGA)

A

a co-enzyme/donor
compound required to conjugate glucuronic acid,

38
Q

functions of cytochrome p450 enzymes

A
  • detoxification of xenobiotics
  • cellular metabolism
  • homeostasis

liver & friends lectures (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions