Case Study 1:
Person in desert with limited water, concentrated yellow urine.
Identify the hormone.
Answer: ADH (Anti-Diuretic Hormone) or Vasopressin.
Target site of the hormone.
Answer: Distal Convoluted Tubule (DCT) and Collecting Duct.
Designing: Predict change after drinking water.
Answer: Urine will become dilute (hypotonic) and large in volume as ADH secretion decreases.
Analysis: Osmoregulation.
Answer: The process of maintaining the constant osmotic pressure/water-salt balance of the blood.
Why yellow?
Answer: Presence of Urochrome, a pigment formed from the breakdown of hemoglobin.
Case Study 2:
Patient undergoing Haemodialysis.
6. Principle of dialysis.
Answer: Diffusion/Osmosis across a semi-permeable (cellophane) membrane.
Why compose fluid like plasma without waste?
Answer: To create a concentration gradient so nitrogenous wastes (Urea) move from blood to fluid, while essential nutrients remain in the blood.
Creating: Dialysis diagram.
Answer: [Description: Blood pumped from artery through tubes in a tank of dialysing fluid, then returned to a vein].
Critical Thinking: Why not a permanent cure?
Answer: It only filters waste; it cannot perform other kidney functions like hormone production (Erythropoietin) or active regulation. Kidney transplant is the permanent solution.
Survive with one kidney?
Answer: Yes. The remaining kidney undergoes compensatory hypertrophy (increases in size and function) to handle the load.
Answer: [Description: Cup-like Bowman's capsule surrounding a tuft of capillaries].
Application: Drink water in summer.
Answer: To compensate for water lost through sweating (thermoregulation) and prevent dehydration/concentrated urine.
Creating: Glomerulus mimic.
Answer: A high-pressure pump pushing liquid through an ultra-fine mesh filter.
Analysis: Threshold Substance.
Answer: A substance reabsorbed efficiently by the kidney. Glucose is "high-threshold" because it's only excreted if its blood level exceeds a certain limit (Renal threshold).
Designing: Kidney stone diet.
Answer: Avoid spinach, tomatoes, and nuts (high in oxalates). Increase water intake.
Creating: Kidney-Brain dialogue.
Answer: Kidney: "Hey Brain, the blood is too salty!" Brain: "Copy that, releasing ADH now. Hold onto that water!"
Answer: Filtration under high pressure where almost all liquid components (except proteins/cells) are forced out.
Scenario: Blood in urine (Haematuria).
Answer: Possible kidney stone or infection causing damage to the urinary tract lining.
Critical Thinking: Ammonia vs Urea.
Answer: Ammonia is highly toxic and needs lots of water to flush; suitable for fish. Urea is less toxic and conserves water; suitable for land mammals.
Application: Gout.
Answer: Inflammation of joints due to accumulation of Uric acid crystals.
Excretion vs Egestion.
Answer: Excretion: Removal of metabolic waste from cells. Egestion: Removal of undigested food from the gut.
Diagram Based: Urinary system.
Answer: Sphincter muscles control the release of urine from the bladder (voluntary control).
Skin in excretion.
Answer: Sweat glands remove water, salts, and small amounts of urea.
Analysis: Right kidney lower.
Answer: Due to the large space occupied by the liver on the right side.
Competency: Counter-current mechanism.
Answer: The flow of filtrate in opposite directions in the two limbs of the Loop of Henle helps build an osmotic gradient in the medulla to concentrate urine.
Case: High protein effect.
Answer: More protein -> More deamination in liver -> More Urea in blood -> More Urea in urine.
Creating: Caffeine hypothesis.
Answer: Caffeine increases blood flow to kidneys and inhibits ADH, increasing urine output.