🌱 Biology Notes: Excretion Beyond Kidneys
Here’s how different organs help remove waste from your body! 😊
💦 Urine Basics
- Micturition: The process of releasing urine
- Bladder muscles contract 🌀
- Urethral sphincter relaxes ⬇️
- Controlled by micturition reflex
- Daily urine output: 1-1.5 liters (adults)
- Urine properties:
- Light yellow, watery 💛
- Slightly acidic (pH ~6.0)
- Characteristic odor
- Contains ~25-30 g urea/day
- Urine analysis detects health issues:
- Glucose (Glycosuria) → Diabetes
- Ketone bodies (Ketonuria) → Diabetes
🌬️ Lungs in Excretion
- Removes:
- \( \text{CO}_2 \) (~200 mL/minute)
- Significant water daily 💧
Fun fact: You exhale waste gases all day!
🧴 Liver in Excretion
- Secretes bile containing:
- Bilirubin/biliverdin (from old red blood cells) 🩸
- Cholesterol
- Degraded steroid hormones
- Vitamins/drugs 💊
These exit with digestive waste (poop!)
🧖 Skin in Excretion
- Sweat glands:
- Sweat = Water + NaCl + Urea (tiny!) + Lactic acid
- Main job: Cools body ❄️
- Bonus: Removes some wastes!
- Sebaceous glands:
- Sebum (oily) removes sterols, hydrocarbons, waxes 🛢️
- Protects skin with oily layer
🦠 Disorders
- Uremia:
- Kidney malfunction → Urea buildup in blood ☠️
- Can cause kidney failure
- Treatment: Hemodialysis (artificial kidney)
- Blood from artery → Dialysing unit + Anticoagulant (heparin) 💉
- Waste filtered via cellophane tube
💡 NEET Must-Knows
- Micturition reflex: Neural control of urine release
- Urine traits: pH (~6.0), urea (25-30 g/day), volume (1-1.5 L/day)
- Organs & their wastes:
- Lungs → \( \text{CO}_2 \) + H₂O
- Liver → Bile pigments (bilirubin)
- Skin → Urea/salts (sweat), sterols (sebum)
- Uremia & hemodialysis: Blood filtration during kidney failure
Keep revising – you’re doing great! 🌟
