Liver function 1

Question 1

Excretion

Answer 1

Removal of metabolic waste and u wanted substances ( by products) from the body

Question 2

Main substances removed

Answer 2

Carbon dioxide - from cellular respiration

Urea - excess amino acids

Question 3

Carbon dioxide released and transported as ..

Answer 3

Hydrogencarbonate ions
Carbaminohaemoglobin
Carbonic acid

Question 4

High levels of co2 lead to

Answer 4

Increase in blood ph ( respirator acidosis)

Below 7.35 – slow difficult breathing

Question 5

Amino acid removal 1

Answer 5

Body cannot store excess but doesn’t want to waste so is excreted

1) deamination : in liver- toxic amino group removed to leave ammonia

Carboxylic group and r group form keto acid

2) ammonia reacts with co2 to form urea

Question 6

Uses of ammonia and keto acids

Answer 6

Ammonia :
•soluble
•toxic
•cannot be accumulated in blood so must be converted to less toxic form ( urea)

Keto :
• used in Krebs cycle and turned into lipids and cholesterol

Question 7

Ornithine cycle

Answer 7

Ammonia combined with carbon dioxide to form urea

1) ammonia and co2 combine with amino acid ornithine to produce citrulline (h20 released)
2) addition of further ammonia so converted to arginine (h20 released )
3) addition of H20 and removal of urea so reconverted to orthinine

Question 8

Detoxification

Answer 8

•occurs in smooth £R of hepatocytes

• liver produces hydrogen peroxide
• catalase enzyme breaks this down to oxygen and water

•cytochrome : breaks down cocaine

Question 9

Why to Detoxification of alcohol

Answer 9

•small lipid molecules can easily diffuse across plasma membranes and enter cells - alcohol enters rapidly and is toxic so can cause harm and must be broken down to small harmless substances

Question 10

How detoxification of alcohol happens

Answer 10

1) ethanol broken down ethanAL by enzyme ethanol dehydrogenase
2) ethanaAL dehydrogenated by ethanAL dehydrogenase to form ethanoate
3) combined with coenzyme A to form acetyl coenzyme A which enters aerobic respiration.
4) h atoms from alcohol released and combined with NAD to form NADH

Question 11

Fatty liver

Answer 11

If liver needs to detoxify too much alcohol , it uses up all its NAD so cannot oxidise and break down fatty acids

So fatty acids converted to lips and stored as fats in hepatocytes to liver becomes enlarged