the liver

Question 1

what makes glycogen a good storage molecule?

Answer 1

• insoluble
• compact
• branched

Question 2

glycogen is an important polyasaccharide found in the cytoplasm of …….. and …… cells

Answer 2

hepatocytes
muscle

Question 3

what is detoxification?

Answer 3

removal of toxic products

Question 4

how is detoxification made possible?

Answer 4

due to the numerous enzymes found in hepatocytes

Question 5

how is ethanol broken down?

Answer 5

ethanol dehydrogenase found in hepatocytes catalyses the removal of 2 hydrogen atoms from each ethanol molecule

Question 6

what happens to the hydrogen atoms removed from the ethanol molecules?

Answer 6

picked up by NAD (a coenzyme) which becomes reduced NAD when it picks up released hydrogen atoms

Question 7

what is deamination?

Answer 7

removal of amino groups because these make amino acids toxic and explain why monomers cannot be stored when in excess

Question 8

why is the amino group removed?

Answer 8

amino acid molecules contain a lot of energy so would be wasteful to excrete a whole molecule

Question 9

what happens to ammonia after production by deamination?

Answer 9

due to high toxicity and solubility it is immediately converted into a less soluble substance

Question 10

how are erythrocytes disposed?

Answer 10

• become fragile with age
• removed by phagocytic cells in spleen, liver and bone marrow
• may rupture and release Hb into plasma

Question 11

where does the liver receive blood from?

Answer 11

hepatic artery
hepatic portal vein

Question 12

what type of blood enters the liver via the hepatic artery?

Answer 12

oxygenated

Question 13

what type of blood enters the liver via the hepatic portal vein?

Answer 13

deoxygenated

Question 14

where does blood leave the liver?

Answer 14

hepatic central vein

Question 15

state the 3 functions of the liver

Answer 15

• deamination
• glycogen storage
• detoxification of ethanol and hydrogen peroxide

Question 16

describe deamination

Answer 16

conversion of amino acids to keto acids which can be respired, and to ammonia which immediately reacts with CO2 to produce urea in the orithinine cycle

Question 17

what is the importance of removing urea?

Answer 17

it is toxic

Question 18

what is the importance of removing CO2?

Answer 18

excess CO2 in blood is toxic due to decreasing blood pH & reducing oxygen transport as binds to Hb

Question 19

define excretion

Answer 19

the removal of toxic metabolic waste (unwanted substances/byproduct of cellular processes) from the body

Question 20

what are kupffer cells?

Answer 20

macrophages which engulf foreign particles and protect against disease

Question 21

what are hepatocytes?

Answer 21

liver cells which produce bile using old blood/blood cells which is secreted into the canaliculi, into the bile duct and into the gall bladder