renal system

• Renal system


  The system responsible for controlling the composition, volume and pressure of blood (homeostasis)
• Kidneys


  • Bean-shaped organs located on the posterior wall of the abdomen, partly protected by the lower rib cage
  • The right kidney is slightly lower than the left, due to the space taken up by the liver
  • Each kidney has over a million nephrons (filtration units) and numerous collecting ducts to transport urine
• Functions of the kidneys


  1. Filtration of waste products and toxins from the blood

  2. Formation of urine

  3. Regulation of water and salt balance in the body

  4. Regulation of blood pressure and blood volume

  5. Maintenance of the normal pH balance in the blood
• Ureters


  Carry urine from the kidneys to the bladder
• Bladder


  A pear-shaped sac in the pelvic cavity which stores urine until it is expelled via the urethra
• Urethra


  • The tube that carries urine from the bladder out of the body
  • In females it is about 4 cm long, in males it is 18-20 cm long
• Urinary tract infections (UTIs)


  • Common, especially in females
  • Symptoms: pain or burning sensation when urinating, frequent urination, lower abdominal pain, cloudy or dark, strong smelling urine
  • Treatment: Most UTIs do not require treatment, but a short course of antibiotics may be prescribed
  • Long-term complications are rare, but may include kidney damage
  • Good personal hygiene and drinking cranberry juice regularly can help prevent UTIs
• Micturition (urination)


  1. Urethral sphincter muscle relaxes

  2. Muscular contractions occur in the bladder wall, forcing the urine out through the urethra
• Renal failure


  Occurs when the kidneys' ability to carry out their normal functions are impaired
• Acute renal failure


  • Rapid onset (less than two days)
  • Symptoms: fatigue, oedema (swelling due to fluid retention in tissues), kidney pain, hand tremor, decreased appetite and changes in urination habits
  • Treatment: diuretic drugs, intravenous fluids and electrolytes, and possible short-term dialysis
• Chronic renal failure


  • Asymptomatic (symptomless) in the early stages
  • Symptoms: tiredness, oedema, nausea, blood in the urine and confusion, developing as the disease progresses
  • Treatment: diagnosis is usually by blood or urine testing, no cure but can sometimes be controlled by medication, dialysis or kidney transplant may be considered
• Why oedema may be a symptom of kidney failure

  If the kidneys stop working properly, blood and tissue fluid cannot be regulated properly, leading to fluid retention and oedema