The Mammalian urinary and excretory system

• Osmoregulation


  The active regulation of body fluids and ion balance in an organism
• Plants


  • Have no specific osmoregulatory organs
  • Have stomata below their leaves that regulate the amount of water loss
• Osmoconformers


  Animals that permit the osmolarity of their body fluids to fit that of the environment (e.g. Marine invertebrates)
• Osmoregulators


  Animals that keep the osmolarity of body fluids different from that of the environment (e.g most marine vertebrates, birds, mammals)
• Nitrogenous wastes expelled by animals

  • Ammonia
  • Urea
  • Uric acid
• Ammonia


  Very poisonous to cells and excreted by aquatic invertebrates, teleosts, and larval amphibians
• Urea


  Excreted down mainly in the urine of mammals
• Uric acid


  Nitrogenous wastes and water insoluble
• Kidneys


  • The main osmoregulatory and excretory organ in mammals
• Parts of the urinary system

  • Two kidneys
  • Ureters
  • Urinary bladder
  • Urethra
• Parts of the kidney

  • Renal capsule
  • Cortex
  • Medulla
  • Nephrons
  • Renal pelvis
  • ureter
• Components of nephrons

  • Bowman's capsule
  • Renal tubules
  • Peritubular capillaries
  • Collecting duct
• Bowman's capsule


  Cuplike capsule that completely surrounds the glumerulus and collects and directs the filtrate through the continuous renal tubules
• Glumerulus


  Made up of network of capillaries where initial filtration of the blood plasma occurs
• Parts of the renal tubules

  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
• Proximal convoluted tubule


  Reabsorbs ions, water and nutrients and removes toxins and adjust filtrate pH
• Loop of Henle


  Long U-shaped portion of the tubule that runs urine within each nephron of the kidney
• Distal convoluted tubule


  Selectively selects and absorbs different ions to maintain blood pH and electrolytes balance
• Components of peritubular capillaries

  • Afferent arteriole
  • Efferent arteriole
• Afferent arteriole


  Group of blood vessels that supply the nephron in many excretory system
• Efferent arteriole


  Blood vessels that carries blood out away from glomerulus
• Collecting duct


  Receives the urine from the renal tubule leading to the renal pelvis
• osmoregulation - active regulation of body fluids and ion balance in an organism. 
• The urethra is a tube leading to the body surface.
• Ureter is a tube directing to a urinary bladder
• Nephron is a functional unit of the kidneys responsible for filtering blood and producing urine.
• . Renal capsule - the outer coat of connective tissue that covers the surface of each kidney
• Cortex


  The zone near the capsule made up of blood vessels and nephrons
• Medulla


  Inner zone also made up of blood vessels and nephrons
• Nephrons


  The functional units of the kidney where urine is formed
• Renal pelvis


  Central cavity in the kidney where urine coming from the nephrons is stationed before going to the ureter
• Ureters


  Urine bearing tubes that withdraw from kidney and discharge into the urinary bladder
• Renal Tubules


  A long and convoluted structure that emerges from glumerulus that receive and modify the glomerular filtrate
• Peritubular Capillaries


  • Bring substances to and take substances away to the renal pelvis