the renal system

• anuria


  non-passage of urine
• oliguria 


  low output of urine (less than 400ml/day or 2 cups)
• diuresis


  increase in urination rate
• diuretic


  drugs that can increase urine production
• electrolytes


  charged particle ion that conducts an electrical current in an aqueous solution
• electrolytes


  charged particle ion that conducts an electrical current in an aqueous solution
• blood chemistry


  urea and electrolytes
• dysuria


  pain or discomfort when passing urine
• nocturia


  need to wake and pass urine at night
• urgency and frequency


  need to increase urination rate due to conditions such as infection, drinking too much liquid, drinking caffeinated or alcoholic beverages, diabetes, pregnancy
• micturition 


  process of urination (also called urination or voiding)
• pyelitis


  infection of renal pelvis and calices
• Pyelonephritis


  infection of the whole kidney
• urology 


  study of urinary system
• renal anatomy

  • Two kidneys – retroperitoneal (behind the parietal peritoneum – i.e. separated from the abdominal cavity)
  • Position – posterior abdominal wall just under the ribcage
  • At the top of the kidney is an adrenal gland (unrelated)
  • Protected by fat (cushioning from mechanical trauma)
  • Has a fibrous capsule (prevents infections reaching the kidney from surrounding regions) and fascia (anchors the kidney and adrenal glands to surrounding tissues)
  • The functional unit is the nephron
• blood flow

  • Aorta – renal artery – smaller branching arteries – afferent arteriole – glomerular
  • capillaries – efferent arteriole – smaller branching veins – renal vein – inferior vena cava
  • Efferent arteriole also supplies branches to:
  • Peritubular capillaries – for reabsorption and secretion between nephron and blood
  • Vasa recta – capillaries around the Loop of Henle to allow urine to be concentrated
• function of the kidney

  • Mainly formation of urine and excretion of waste products and toxins
  • Other functions are to maintain homeostasis by:
  • Help regulate fluid balance electrolytes and acid- base balance (e.g. reabsorb Ca2+ and excretes phosphate)
  • Produce renin – to help regulate blood pressure
  • Produces erythropoetin (stimulates red bone marrow to produce red blood cells – production stimulated by hypoxaemia)
  • Metabolism of vitamin D
• the nephron

  • Functional unit of the kidney
  • Approx. 1 million per kidney
  • Consists of:
  • Glomerus
  • Bowman’s capsule (glomerular)
  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
  • Collecting duct
  • The glomerulus (network of capillaries) sits inside the glomerular capsule
• What is the first stage of urine formation?

  Glomerular filtration
• What occurs during glomerular filtration?

  Movements of H2O and solutes from blood into filtrate under pressure
• What is the second stage of urine formation?

  Tubular reabsorption
• What happens during tubular reabsorption?

  Return of useful substances and water from filtrate into the blood
• What is the third stage of urine formation?

  Tubular secretion and urine production
• What occurs during tubular secretion?

  Active removal of unwanted substances/wastes from the blood into the filtrate
• What is the chemical composition of urine?

  • Water: 95%
  • Solutes: 5%
  • Urea
  • Sodium
  • Potassium
  • Phosphate
  • Sulphate
  • Creatinine
  • Uric acid
• What does GFR stand for?

  Glomerular filtration rate
• What is the approximate GFR value?

  125 ml/min
• How is GFR maintained?

  By autoregulation
• When might a doctor order a GFR test?

  If there are signs that the kidneys are not working well
• What is the role of antidiuretic hormone (ADH) in urine formation?

  It influences the permeability of the collecting duct
• What do aquaporin channels allow?

  Movement of water
• How is plasma osmolality detected?

  By osmo-receptors in the hypothalamus
• How does ADH secretion change in response to high osmolality?

  ADH secretion is increased
• What happens when ADH levels increase?

  Greater reabsorption leading to less urine
• What happens when ADH levels decrease?

  Less reabsorption leading to more urine
• What are the stages of urine formation?

  1. Glomerular filtration
  2. Tubular reabsorption
  3. Tubular secretion and urine production
• What is a red flag symptom indicating a serious renal issue?

  Anuria
• What symptoms accompany dysuria that are considered red flags?

  Fever, flank pain, back pain, or weakness of legs
• Why is haematuria concerning in patients over 50 years old?

  It may indicate serious conditions like hypertension and oedema
• What sudden onset symptom in a young child, accompanied by night sweats and weight loss, is a red flag?

  Polyuria