Regulation of Body Fluids

• Homeostasis

  • it refers to the relatively stable state inside the body of an animal.
  • it maintains the equilibrium around a specific value of some aspect of the body or its cells called a set point.
• Stimulus

  • a change in the internal or external environment, and it is detected by a receptor.
• Osmoregulation

  • the active regulation of osmotic pressure to maintain the balance of water and electrolytes in an organism.
  • it is vital since it is needed to perform biochemical reactions and preserve homeostasis.
• Osmosis

  • the movement of solvent molecules through a semi-permeable membrane into an are that has a higher concentration (low to high).
• Osmotic Pressure

  • the external pressure needed to prevent the solvent from crossing the membrane.
  • depends on the concentration of solute particles.
• Regulators and Conformers

  • Two major types:
  • Osmoconformers
  • Osmoregulators
• Osmoconformers

  • uses active or passive processes to match their internal osmolarity to that of the environment.
  • Evident in marine invertebrates where the internal osmotic pressure inside the cell is the same as the outside water.
• Osmoregulators

  • controls internal osmotic pressure so that conditions are maintained within a tightly-regulated range.
  • Vertebrates (Humans) are osmoregulators.
• Osmoregulation Strategy of Bacterias

  • bacterias use transport mechanisms to absorb electrolytes or small organic molecules, this activates genes in certain bacteria that lead to the synthesis of osmoprotectant molecules.
• Osmoregulation Strategies of Protozoas

  • uses contractile vacuoles to transport ammonia and other wastes from the cytoplasm to the cell membrane.
  • Osmotic pressure forces water into the cytoplasm, while diffusion and active transport control the water and electrolytes.
• Osmoregulation Strategy of Plants

  • Higher plants use the stomata to control water loss; plant cells rely on vacuoles to regulate cytoplasm osmolarity.
• Osmoregulation Strategy of Plants (Mesophytes)

  • Plants in hydrated soil (mesophytes) absorb more water to compensate for water loss.
  • its leaves and stem are protected by a waxy outer coating called the cuticle.
• Osmoregulation Strategy of Plants (Xerophytes)

  • Plants in dry habitats (xerophytes) store water in vacuoles, thick cuticles, and structural modifications to prevent water loss.
• Osmoregulation Strategy of Plants (Halophytes)

  • Plants in salty environments (halophytes) store salts in their roots so that the low water potential will draw the solvent in via osmosis; salt may be excreted onto leaves to trap water molecules.
• Osmoregulation Strategy of Plants (Hydrophytes)

  • plants that live in water or damp environments (hydrophytes) can absorb water across their entire surface.
• Osmoregulation Strategy of Animals

  • animals utilizes the excretory system to control the amount of water that is lost and to maintain osmotic pressure.
  • Protein metabolism also generates waste molecules that could disrupt the osmotic pressure.
• Osmoregulation Strategy of Animals (Human)

  • Water, glucose, and amino acids may be re-absorbed from the glomerular filtrate in the kidneys; it may also continue to the ureters to the bladder for excretion in urine.
  • The Kidneys maintain the electrolyte balance and regulate blood pressure; however, humans lose water and electrolytes via perspiration.
• Osmoregulation Strategy of Animals (Human)

  • Osmoreceptors in the hypothalamus change in water potential, controlling thirst and secreting ADH (antidiuretic hormone).
  • These ADHs target the endothelial cells in the nephrons of the kidneys; they are unique because they have aquaporins.
  • ADH opens the water channels of the aquaporins, allowing water to flow.