Excretion and the Liver

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Define Excretion
A process of expelling waste matter
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What are the 2 main products that are excreted?
Carbon Dioxide and Nitrogenous waste (urea) and bile pigments (formed in the breakdown of haemoglobin)
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What 2 things happen when you have a high concentration of CO2 in your blood?
1) Haemoglobin has a higher affinity for CO2 than for O2 so less O2 is transferred around the body, 2) Respiratory Acidosis- When the blood becomes too acidic
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What is Respiratory Acidosis?
The blood transports CO2 by binding it to hydrogen ions, the increase in CO2 means more hydrogen ions in the blood which increases the acidity of the blood, it affects the activity of enzymes and you feel weak, nauseous, lightheaded
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What is the livers main functions?
Homeostatic control (blood glucose regulation) and break down of excess amino acids and toxic substances
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What is transamination and why does it happen?
The conversion of one amino acid to another, we need this because the diet doesn't always contain a balance of amino acids that we need
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Briefly describe what deamination is
The removal of an amine group from a molecule
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Why do we need deamination?
The body can't store protein or amino acids, so by removing amino acids you can use part of the molecule for respiration and the other part can be excreted so there is minimal waste
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Describe the process of deamination
Excess amino acids go to the liver, they are split from the amine group which goes to be excreted and the rest of the molecule (keto acid) is used in respiration
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What is Keto Acid?
A by-product produced from deamination
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What happens to Keto Acid after deamination?
It enters the mitochondria where it is respired
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Briefly describe what the ornithine cycle is
A set of enzyme-controlled reactions to convert ammonia to urea to be excreted
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Describe the process of the ornithine cycle
Ammonia is toxic so it is converted into citrulline by combining it with CO2 and ornithine, giving off H2O, this is then converted to arginine by the addition of more ammonia, urea is removed as water added & arginine is converted back to ornithine
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How is hydrogen peroxide broken down in the liver?
The enzyme catalase breaks down HO into hydrogen and oxygen
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How does the liver break down alcohol?
The enzyme alcohol dehydrogenase in hepatocytes breaks down ethanol into ethanal, ethanal is then converted to ethanoate which can be used to build up fatty acids or used in cellular respiration
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Card 2

Front

What are the 2 main products that are excreted?

Back

Carbon Dioxide and Nitrogenous waste (urea) and bile pigments (formed in the breakdown of haemoglobin)

Card 3

Front

What 2 things happen when you have a high concentration of CO2 in your blood?

Back

Preview of the front of card 3

Card 4

Front

What is Respiratory Acidosis?

Back

Preview of the front of card 4

Card 5

Front

What is the livers main functions?

Back

Preview of the front of card 5
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