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Flashcards by molly.rowland1, updated more than 1 year ago
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Created by molly.rowland1
almost 8 years ago
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| Question | Answer |
| Why is the colon not an example of an excretory organ? | Excretion is the removal of METABOLIC waste, the colon removes bulk/fibre that has never been inside cells and is therefore not metabolic waste. |
| In general, why is it important that carbon dioxide and nitrogenous wastes are excreted from the body? | Because they can accumulate to toxic levels. |
| What will happen if carbon dioxide is allowed to accumulate? | It will bind with water to produce carbonic acid, this will dissociate to produce hydrogen ions and hydrogen carbonate ions. This will reduce the pH of the blood. If the pH reduces to below 7.35 then it can cause respiratory acidosis. Carbon dioxide can also bind with haemoglobin to form carbaminohaemoglobin, this reduces the haemoglobins affinity for oxygen, therefore, less oxygen is transported around the body. |
| What are the symptoms of respiratory acidosis? | Slowed breathing. Headache. Drowsiness. Tremors. Confusion. |
| How does the body respond to increased carbon dioxide concentration? | High levels of carbon dioxide are detected by chemoreceptors. The respiratory centre in the medulla oblongata then increases breathing rate so that the carbon dioxide is excreted by the lungs. The H+ ions will be removed by the kidneys to maintain blood pH. |
| The Western diet is high in protein meaning we consume more than necessary, what happens to the excess protein we consume? | The amine group is removed and the rest is broken down into fats or carbohydrates for storage or use in respiration. |
| Why is the amino group removed? | Because it is toxic. |
| Describe the process in which the amino acid is removed. | Deamination: Amino acid + oxygen --> Ammonia + Keto Acid. |
| What is the use of the products of deamination? | The ammonia is of no use, it is soluble and toxic so it is converted into urea before being excreted. However, the keto acid is used as a respiratory substrate. |
| Describe the process where ammonia converted into urea? | The ornithine cycle: Ornithine is converted into citrulline by the use of CO2 and NH3, water is also released, (ATP-ADP). The citrulline is then converted into arginine with the use of more ammonia, more water is released. Arginine then uses water to release urea, then ornithine is formed again and the cycle continues. |
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