Higher Tier: ADH and nitrogen waste
| English | 中文 | Pinyin |
|---|---|---|
| ADH/ˌeɪ diː ˈeɪtʃ/ | 抗利尿激素 | kàng lì niào jī sù |
| deamination/ˌdiːmɪˈneɪʃn/ | 脱氨基作用 | tuō ān jī zuò yòng |
What would explain this observation?
- Higher Tier: The liver processes excess amino acids, while the kidneys remove the resulting waste. Water balance additionally needs a hormone-controlled adjustment of reabsorption.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Digestion produces amino acids. Excess amino acids are deaminated in the liver, forming ammonia; because ammonia is toxic it is immediately converted to urea for safe excretion. The kidneys remove urea in urine. This separates waste formation in the liver from removal by the kidneys.
- ADH 抗利尿激素: A hormone increasing kidney-tubule water permeability and reabsorption; deamination 脱氨基作用: Removal of the amino group from excess amino acids in the liver.
Which response fits blood that is too concentrated?
When blood is too concentrated, the pituitary releases more ADH. ADH increases the permeability of kidney tubules to water, so more water is reabsorbed into blood. Less water remains in urine. As blood returns towards suitable concentration, the stimulus for ADH release decreases: negative feedback opposes the original disturbance.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- When blood is too concentrated, the pituitary releases more ADH. ADH increases the permeability of kidney tubules to water, so more water is reabsorbed into blood. Less water remains in urine. As blood returns towards suitable concentration, the stimulus for ADH release decreases: negative feedback opposes the original disturbance.
- Trace two labelled models: amino acids → liver processing → urea → kidney excretion, and concentrated blood → ADH → permeability → water return. Interpret supplied amounts without confusing hormone concentration with urine volume. Use model evidence only; never investigate dehydration or hormone dosing in participants.
Which two habits make the investigation or model in this case more defensible?
Trace two labelled models: amino acids → liver processing → urea → kidney excretion, and concentrated blood → ADH → permeability → water return. Interpret supplied amounts without confusing hormone concentration with urine volume. Use model evidence only; never investigate dehydration or hormone dosing in participants.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a fictional filtration model has 100 water units. Reabsorption changes from 90 to 96 units under a stated ADH response. Water remaining falls from 10 to 4 units, a 60% decrease. The calculation applies to this fixed filtered amount; it does not give an ADH dose or a universal human urine volume.
A model filters 80 water units and reabsorbs 74. Calculate units remaining. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A model filters 80 water units and reabsorbs 74. Calculate units remaining.
The result is 6 units. Known: a fictional filtration model has 100 water units. Reabsorption changes from 90 to 96 units under a stated ADH response. Water remaining falls from 10 to 4 units, a 60% decrease. The calculation applies to this fixed filtered amount; it does not give an ADH dose or a universal human urine volume.
Check the conclusion and its limits
- ADH changes permeability rather than directly turning water into glucose. More water reabsorption generally means a smaller water volume in urine in the stated model. Ammonia and urea are different, and the liver—not the kidney—is the specified site of deamination and urea formation.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
The kidneys are the specified site of amino-acid deamination. This claim is false: ADH changes permeability rather than directly turning water into glucose. More water reabsorption generally means a smaller water volume in urine in the stated model. Ammonia and urea are different, and the liver—not the kidney—is the specified site of deamination and urea formation.
Higher Tier: ADH and nitrogen waste: When blood is too concentrated, the pituitary releases more ADH. ADH increases the permeability of kidney tubules to water, so more water is reabsorbed into blood. Less water remains in urine. As blood returns towards suitable concentration, the stimulus for ADH release decreases: negative feedback opposes the original disturbance.
The kidneys are the specified site of amino-acid deamination.
ADH changes permeability rather than directly turning water into glucose. More water reabsorption generally means a smaller water volume in urine in the stated model. Ammonia and urea are different, and the liver—not the kidney—is the specified site of deamination and urea formation.
A hormone increasing kidney-tubule water permeability and reabsorption: write the technical term.
ADH means A hormone increasing kidney-tubule water permeability and reabsorption.