Renal System (Part of)

Renal System (Part of)

1. Anatomy

   • Kidney
     • Function
       • Regulating
         • blood electrolyte composition by excreting excessive ions into urine
         • blood pH be excreting/conserving H+ or bicarbonate ions
         • Blood volume by conserving/eliminating water
         • blood pressure via blood volume and by RAAS and ANP
       • Mantaining
         • blood osmolarity by excreting excessive ions into urine
       • Excreting
         • Waste products e.g urea, ammonia
       • Producing
         • Hormones e.g. EPO , calcitriol = producing enzyme renin = production of angiotensin and aldosterone

2. Physiology

3. Components

   • Nephron
     • Renal Corpscle
       • Glomerulus
       • glomerular capsule
     • Renal tubule

4. Hormones and its effect

   • Aldosterone
     • Promotes tubular reabsorption of Na+ = increased water reabsorption
     • Decreased urine output
   • Antidiuretic hormone
     • Increases water permeability in nephron = increased water reabsorption
     • decreased urine output
   • Atrial natriuretic peptide
     • Inhibits tubular reabsorption of Na+ = decreased water reabsorption
     • Increased urine output

5. Urine formation

   • Glomerular formation ; filtration/movement of water and small solutes from Glomerulus to the Glomerular Capsule due to blood pressure
   • Tubular reabsorption ; process of selectively returning back useful substances from the filtrate back to the blood
     • e..g. Glucose , amino acids , water , Na+ , Cl- , Ca2+ , H+ , HCO3-
   • Tubular secretion = selective removal of additional wastes from blood to the filtrate
     • e.g. H+ and K +

6. Full cycle from blood to excretion

7. Ageing

   • Kidney shrink
     • nephrons decrease in size and number
   • Glomerular filtration rate decreases
     • inability to compensate for fluid overload
   • Tubule cells become less effeicient
     • inability to compensate for dehydration
   • Bladder capacity decreases
   • Urinary retention
     • commonly in elderly men due to prostate enlargement