Kidney & Nephron Structure
Cortex, Medulla, Pelvis — and the microscopic nephron that filters your blood
Think of your kidneys as water treatment plants. Dirty water (blood with waste) comes in, gets filtered, and clean water (filtered blood) goes back out. The waste (urine) is sent away through pipes (ureters) to a storage tank (bladder).
Metabolic reactions produce toxic waste. Urea is formed in the liver from excess amino acids (deamination). If urea builds up in the blood, it becomes toxic. The kidneys remove urea, excess water, and excess ions to keep your internal environment stable.
Core: What You Must Know
• CO₂ is excreted through the lungs
• Kidneys excrete urea and excess water and ions
• Identify: Kidneys, Ureters, Bladder, Urethra
⚠️ Excretion ≠ Egestion. Excretion = removing metabolic waste. Egestion = removing undigested food. Urea is excreted; faeces are egested.
⚠️ The kidney does NOT make urea. Urea is made in the LIVER by deamination. The kidney only removes it from blood.
⚠️ Renal artery vs Renal vein: Don't mix them up. Artery = blood IN, Vein = blood OUT. The renal vein carries cleaned blood.
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