case 5 - storage functions of the liver Flashcards

1
Q

how much glycogen is stored in the liver

A

around 100g

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2
Q

describe the steps of the synthesis of glycogen

A

Glucose is converted to Glucose-6-P by glucokinase (hexokinase in skeletal muscle)

Glucose-6-P is converted to Glucose-1-P by phosphoglucomutase

Glucose-1-P is then converted to UDP-Glucose

Finally UDP-glucose is added to the glycogen chain within the liver either by glycogen synthase or branching enzyme

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3
Q

what are the lipid-soluble vitamins A,D,E,K stored in the liver as

A

vitamin b12

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4
Q

where is vitamin A stored in the liver and what as

A

stored in the stellate cells as retinyl ester

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5
Q

what is the active form of retinyl ester

A

retinol

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6
Q

how is retinol converted to retinyl ester

A

by lecithin:retinol acyltransferase

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7
Q

what is it called when vitamin D is produced by the body

A

cholecalciferol

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8
Q

what are the functions of vitamin D

A

Maintaining normal serum calcium and phosphate concentrations

Increased absorption of calcium in the kidneys and intestines

Increased mobilisation of calcium from bone , activating osteoclasts to release more calcium

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9
Q

where can vitamin E be stored

A

in the liver or adipose tissue

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10
Q

what are the function of vitamin E

A

antioxidant
preventing the propagation of free radicals
protects vitamin A

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11
Q

what are the function of vitamin K

A

Important for synthesis of clotting factors II, VII, IX and X.
Co-factor for enzymes

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12
Q

what is another name for vitamin B12

A

cobalamin

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13
Q

what are the functions of vitamin B12

A

Production of DNA and RNA
Maintaining healthy neurones
Red blood cell production – alongside Vitamin B9

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14
Q

what minerals are stored in the liver

A

iron and copper

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15
Q

what is most iron stored within the cells as

A

ferritin

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16
Q

where is the majority of iron stored

A

in the hepatocytes

17
Q

what happens in severe iron overload

A

the ferritin storage becomes saturated and so excess becomes stored within haemosiderin. However haemosiderin is a large, insoluble complex and iron stored within it is difficult to mobilise effectively.