An industrial glassblower works long shifts near high-temperature kilns, during which their body must actively regulate water potential, electrolyte concentrations, and blood glucose levels.
Identify the specific part of the nephron where the selective reabsorption of glucose and amino acids normally takes place.
During a shift, the worker loses a significant volume of body water through thermoregulatory sweating.
State how the concentration of antidiuretic hormone (ADH) in the worker's blood changes in response to this dehydration.
Explain how this change in ADH concentration affects the cells of the collecting duct and describe the subsequent effect on both the volume and concentration of the urine produced.
The table below shows information about three types of hydration and energy recovery fluids recommended for industrial workers:
| Hydration fluid | Osmotic concentration relative to blood | Carbohydrate concentration | Absorption rate |
|---|---|---|---|
| Solution Alpha (Hypotonic) | Lower | < 2.5% | Extremely rapid |
| Solution Beta (Isotonic) | Equal | 4%−7%4\% - 7\%4%−7% | Rapid |
| Solution Gamma (Hypertonic) | Higher | > 9% | Slow |
Occupational health guidelines recommend that glassblowers drink Solution Gamma 1 hour before starting their strenuous shift, and consume Solution Beta rather than pure water during and immediately after completing their shift.
Explain the biological reasons behind these recommendations and their timing.
22 exam-style questions on OCR GCSE Biology 3.3 Maintaining internal environments, covering 3.3.1 Importance of a constant internal environment, 3.3.2 The skin and body temperature, 3.3.3 Insulin and blood sugar, 3.3.4 Glucagon and blood sugar, 3.3.5 Type 1 and type 2 diabetes, 3.3.6 Osmotic changes in body fluids, 3.3.7 Kidneys and water balance, 3.3.8 Structure of the kidney and tubule, 3.3.9 ADH and kidney tubule permeability, and 3.3.10 Responses to temperature and osmotic challenges. Each one has a worked solution and a mark scheme showing where the marks go.