5.1.2 (b) the Liver

Question 1

what are the 3 vessels connected to the liver?

Answer 1

hepatic artery
hepatic vein
hepatic portal vein

Question 2

which vessel removes blood from the liver?

Answer 2

hepatic vein

Question 3

which vessels bring blood to the liver?

Answer 3

hepatic artery and hepatic portal vein

Question 4

what is the composition of the blood in the hepatic artery?

Answer 4

this is oxygenated blood from the heart

Question 5

what is the composition of the blood in the hepatic portal vein?

Answer 5

this is blood containing high concentrations of nutrients from the intestines to allow for metabolic activity in the liver

Question 6

what cells make up the liver?

Answer 6

hepatocytes

Question 7

what are the features of a hepatocyte?

Answer 7

they have a large nucleus
they have a prominent golgi complex
they have LOTS of mitochondria

Question 8

why do hepatocytes have a lot of mitochondria?

Answer 8

they are very metabolically active cells

Question 9

why do hepatocytes have a prominent golgi?

Answer 9

they have to secrete lots of vesicles of bile

Question 10

what do hepatocytes do?

Answer 10

break down harmful substances in the blood
break down red blood cells into bile

Question 11

where is the blood from the hepatic artery and hepatic portal vein mixed in the liver?

Answer 11

spaces called sinusoids are surrounded by hepatocytes

Question 12

why is the blood mixed in the liver?

Answer 12

this increases the oxygen content of the blood

Question 13

what are Kuppfer cells?

Answer 13

they are found on hepatocytes and ingest pathogens and protect the liver from disease

Question 14

where does the bile secreted from the hepatocytes go to?

Answer 14

the Canaliculus which drains the bile into the bile ductiles and then into the gall bladder

Question 15

micrograph of a liver tissue

Answer 15

Question 16

what are the main functions of the liver?

Answer 16

carbohydrate metabolism
deamination of amino acids
detoxification

Question 17

how does the liver react to insulin?

Answer 17

when insulin levels rise due to a high blood glucose level, hepatocytes are stimulated to convert glucose into glycogen

GLYCOGENESIS

so the liver is a good store of glycogen

Question 18

how does the liver react to glucagon?

Answer 18

when glucagon levels rise due to a low blood glucose level, hepatocytes are stimulated to convert glycogen into glucose

GLYCOGENOLYSIS

Question 19

what is transamination?

Answer 19

the conversion of one amino acid into another

Question 20

why is transamination important?

Answer 20

allows diet to be balanced with different amino acids

Question 21

what is deamination?

Answer 21

the removal of an amine group from a molecule

Question 22

why must proteins and amino acids be deaminated?

Answer 22

proteins and amino acids cannot be stored in the body

Question 23

what do hepatocytes produce as a waste product of deamination?

Answer 23

they convert the amino group into ammonia and then into urea

Question 24

why can’t ammonia just be excreted instead of converting it to urea?

Answer 24

ammonia is too toxic to be excreted directly by mammals

Question 25

what happens to urea produced in deamination?

Answer 25

transported and excreted by the kidneys

Question 26

what happens to the rest of the amino acid?

Answer 26

it is used in cellular respiration or converted into lipids for storage

Question 27

what cycle converts ammonia into urea?

Answer 27

the ornithine cycle

Question 28

ammonia and carbon dioxide and ornithine

Answer 28

citruline and water

Question 29

citruline and ammonia

Answer 29

arginine and water

Question 30

arginine and water

Answer 30

urea and ornithine

Question 31

generalisation of ornithine cycle

Answer 31

ammonia + carbon dioxide forms urea + water

Question 32

what is detoxification?

Answer 32

when toxic substances are made harmless

Question 33

what two substances can the liver detoxify?

Answer 33

hydrogen peroxide ethanol

Question 34

what enzyme do hepatocytes contain to break down hydrogen peroxide?

Answer 34

catalase

Question 35

what does catalase split hydrogen peroxide into?

Answer 35

oxygen and water

Question 36

what enzyme do hepatocytes contain to detoxify ethanol?

Answer 36

alcohol dehydrogenase

Question 37

what is ethanol broken down into?

Answer 37

ethanal and then to ethanoate

Question 38

why is it important to detoxify ethanol?

Answer 38

excess ethanol can lead to cirrhosis of the liver liver cells end up dying

Question 39

what is wider the hepatic portal vein or hepatic artery?

Answer 39

hepatic portal vein

Question 40

which is branched hepatic portal vein or hepatic artery?

Answer 40

hepatic portal vein

Question 41

how are hormones excreted from the body?

Answer 41

hepatocytes remove the NH2 group (deamination) converts into ammonia ammonia enters ornthine cycle and urea is formed urea leaves via the kidney