Q1: Difference between Ammonotelism, Ureotelism, and Uricotelism.

Answer: This classification is based on "What" they excrete and "How much water" they need.

Feature Ammonotelism 🐟 Ureotelism 🦁 Uricotelism 🦅
Waste Ammonia Urea Uric Acid
Danger Most Toxic (Needs huge water to dilute) Less Toxic Least Toxic
Water Need Maximum Moderate Minimum (Paste/Pellet)
Who? Bony Fishes, Aquatic Insects Humans, Mammals, Frogs Birds, Reptiles, Insects

Q2: Structure and Function of the Malpighian Body.

Answer: The Malpighian Body (Renal Corpuscle) is the "Filtering Unit" at the start of the nephron. It has two parts:

  1. Glomerulus: A ball of capillaries. Think of it as the "Sieve". It filters blood under high pressure.
  2. Bowman's Capsule: A double-walled cup that holds the Glomerulus. The inner wall has special cells called Podocytes (foot cells) that create tiny filtration slits.
  • Function: Ultrafiltration. It filters out almost everything from the plasma (except big proteins) to form the filtrate.

Q3: Why does the PCT have a "Brush Border" epithelium?

Answer: Imagine trying to dry yourself with a smooth plastic sheet versus a fluffy towel. The towel works better because the loops increase surface area.

  • The PCT (Proximal Convoluted Tubule) has a Brush Border (Microvilli) to hugely increase the surface area.
  • Why? Because the PCT is the "Main Reabsorber". It needs to soak up 70-80% of electrolytes and water, plus 100% of nutrients like Glucose.

Q4: What is the role of the Counter Current Mechanism?

Answer: This mechanism acts like a "Salt Multiplier" to help us save water.

  • Who does it? The Loop of Henle and the Vasa Recta (blood vessels).
  • How? They flow in opposite directions (Counter Current) to trap NaCl and Urea deep in the kidney (Medulla).
  • Result: This makes the kidney tissue very salty (High Osmolarity: 1200 mOsmol/L). This saltiness pulls water out of the urine in the Collecting Duct, allowing us to produce Concentrated Urine.

Q5: How does the JGA regulate kidney function?

Answer: The JGA (Juxta Glomerular Apparatus) is the kidney's "Emergency Pressure System".

  • Trigger: Low Blood Pressure or Low GFR.
  • Action: JGA releases Renin.
  • Pathway (RAAS): Renin →\rightarrow Angiotensinogen →\rightarrow Angiotensin II.
  • Effect: Angiotensin II squeezes blood vessels (raises BP) and triggers Aldosterone (saves Salt & Water). This restores the GFR.

Q6: Define GFR and give its normal value.

Answer: GFR (Glomerular Filtration Rate) is the speed at which your kidneys filter blood. It is the amount of filtrate formed by both kidneys in one minute.

  • Normal Value: 125 ml/minute.
  • Fun Fact: That adds up to 180 Litres per day! (But we reabsorb 99% of it).

Q7: What is the function of ADH?

Answer: ADH (Antidiuretic Hormone) is the "Anti-Pee" hormone.

  • When? When you are thirsty or dehydrated (low body fluid).
  • Action: It tells the kidney tubules (DCT & Collecting Duct) to open their doors and absorb more water back into the blood.
  • Result: You pee less, and your urine becomes concentrated.

Q8: Difference between Cortical and Juxtamedullary nephrons.

Answer:

Feature Cortical Nephrons (The Majority - 85%) Juxtamedullary Nephrons (The Specialist - 15%)
Loop Length Short (Barely touches medulla) Very Long (Runs deep into medulla)
Vasa Recta Absent or reduced Prominent (Highly developed)
Function Normal filtration Concentrating Urine (Water conservation)

Q9: What is the role of the Liver in excretion?

Answer: The Liver is the body's "Detox Center".

  1. Urea Cycle: It converts highly toxic Ammonia into less toxic Urea so the kidneys can handle it.
  2. Waste Dumping: It filters out dead blood cell pigments (Bilirubin, Biliverdin), drugs, and excess vitamins, dumping them into the Bile to be pooped out.

Q10: Why is Tubular Secretion important?

Answer: Think of Filtration as "dumping the drawer" and Reabsorption as "picking up the good stuff". Secretion is the final check where we manually throw out specific trash.

  • The tubules actively dump H+H^+, K+K^+, and Ammonia into the urine.
  • Importance: This is crucial to maintain the Ionic Balance and pH Balance of the blood.

Q11: Describe the process of Hemodialysis.

Answer: This is the "Artificial Kidney" for patients with Uremia.

  1. Take Out: Blood is taken from an Artery and mixed with Heparin (to stop clotting).
  2. Filter: It goes into a machine with a cellophane tube surrounded by fluid. The fluid has NO waste. So, waste from the blood diffuses OUT into the fluid.
  3. Put Back: The clean blood is mixed with Anti-heparin and put back into a Vein.

Q12: What is Micturition?

Answer: Micturition is the scientific term for urination (emptying the bladder).

  • Mechanism: It's a reflex. Bladder Fills →\rightarrow Stretch Receptors Fire →\rightarrow Signal to CNS →\rightarrow CNS commands Bladder to Squeeze & Sphincter to Open.

Q13: Constituents of Sweat and Sebum.

Answer:

  • Sweat (The Cooler): Watery fluid + Salt (NaClNaCl) + Small amounts of Urea & Lactic Acid.
  • Sebum (The Oiler): Oily/Waxy fluid + Sterols + Hydrocarbons + Waxes.

Q14: Glycosuria vs. Ketonuria.

Answer:

  • Glycosuria: Glucose (Sugar) in the urine.
  • Ketonuria: Ketone bodies in the urine.
  • Significance: If a doctor sees both of these in your urine report, it is a classic sign of Diabetes Mellitus.

Q15: Why is human urine slightly acidic?

Answer: Our urine usually has a pH of 6.0 (Acidic). This is because our kidneys actively secrete Hydrogen ions (H+H^+) from the blood into the urine to keep our blood pH neutral. Basically, we dump the acid out to stay balanced.