osmoregulation

• Osmoregulation


  Animals' ways of maintaining water (and solute) balance
• Excretory system


  • Regulates and maintains homeostasis in regards to water and solute levels
  • Balances expelling nitrogenous waste with retaining water and important solutes
• Excretory system


  1. Filtration

  2. Reabsorption

  3. Secretion

  4. Excretion
• Nephrons


  Functional excretory units in the kidney

  
• Filtrate includes water, ions, urea, glucose, amino acids, drugs/toxins
• Reabsorption


  Active and passive transport
• Solute concentration (osmolarity) of the interstitial fluid increases towards the center of the kidney</b>

  
• Overall the filtrate is highly reduced in volume, highly reduced in important solute concentrations, and highly concentrated in waste solutes
• Antidiuretic hormone (ADH) or vasopressin (AVP)

  Triggered by increase in blood osmolarity, makes collecting duct of nephrons more permeable to water, increases water retention

  
• In a hypotonic environment, the body removes water and retains salt. In a hypertonic environment, the body retains water and removes salt.
• A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that it operates an extensive set of active-transport ion pumps.