The Concept of Osmoregulation Presentation

A Balancing Act

• Physiological processes of organisms’ operation in environment.
• Relative concentrations of fluids and solutes maintained at optimal levels.
• Osmoregulation controls solute concentrations and balances the gain and loss of water.
• Freshwater animals have adaptations to limit water uptake and conserve solutes.
• Desert and marine animals are exposed to harsh environments that quickly deplete body fluids.
• Excretion leads to removal of nitrogenous wastes and other waste products.

Osmoregulation

• Active regulation of the osmotic pressure (osmoregulation).
• Maintain the homeostasis of water content.
• Prevents too diluted or too concentrated body fluids.
• Sustain right fluid concentration.
• Osmotic pressure is required.
• Osmosis is observed.
• Higher osmotic pressure causes more water movement.
• Aquatic and terrestrial organisms must sustain the right solute concentration.
• Osmoregulation is based mainly on controlled flow of solutes between internal fluids and the external environment.

Osmosis and Osmolarity

• Cells need stability between osmotic gain and water loss.
• Osmolarity refers to solute concentration.
• Osmolarity controls the flow of water across a selective permeable membrane.
• Isoosmotic solutions have equal movement of water particles.
• Differences in osmolarity lead to water movement from the hypoosmotic to the hyperosmotic solution.

Osmotic Challenges

• Osmoconformers (mainly consisting of certain marine animals) are isoosmotic with their environment and thus do not control osmolarity.
• Osmoregulators consume energy to regulate water absorption and loss in hyperosmotic or hypoosmotic environment.
• Many animals are stenohaline, i.e., they cannot withstand significant fluctuations in external osmolarity.
• Euryhaline organisms are able to survive major fluctuations in external osmolarity.

Osmoregulation & Excretion

• Kidney function:
  • Keep a balance of body salts at optimal:
    • A challenge with terrestrial organisms is water conservation;
    • There is a need to replace lost water;
    • Animals can conserve water;
    • Adaptation mechanisms are necessary for terrestrial organisms such as producing concentrated urine, being active at night and drinking among others.
  • Remove metabolic wastes;
  • The main challenge is nitrogenous wastes from protein;
  • Getting rid of nitrogenous wastes as:
    • Ammonia;
    • Urea;
    • Uric acid.

Excretory Processes

• Excretory systems release urine by refining filtrate fluids obtained from body fluids.
• Major roles of most excretory systems:
  • Filtration: pressure-filtering of body fluids;
  • Reabsorption: reabsorbing useful solutes;
  • Secretion: releasing toxins and other solutes from the body fluids to the filtrate;
  • Excretion: removing the filtrate from the system (Campbell & Reece, 2007).

Hormonal Relations

Antidiuretic Hormone:

• Nervous and hormonal control of water and salt reabsorption in the kidneys control osmolarity of the urine (Agrawal, Agarwal, Joshi, & Ghosh, 2008).
• Antidiuretic hormone (ADH) is responsible for increased water reabsorption in the distal tubules and collecting ducts of the kidney.
• An increase in osmolarity activates the release of ADH to assist in water conservation.
• Impair in ADH production causes serious water loss and results in diabetes insipidus.
• Alcohol is a diuretic and prevents the release of ADH.

Pathophysiology

• Disorders of salt and water balance may occur (Evbuomwan, 2013).
• There are clinical and biochemical changes resulting from this disorder of salt and water balance.
• Such changes result in adverse osmoregulation function.
• Disturbances of osmoregulation in humans are shown through a change in serum sodium concentrations (Sinke & Deen, 2011).
• Serum sodium concentrations cause hypernatremia or hyponatremia.
• Hypernatremia is an increased serum sodium concentration above 145 mM.
• Hyponatremia (serum sodium concentration below 136 mM).

Findings

• A disturbance in the water balance is an abnormality shown in the serum sodium concentration and causes hypernatremia or hyponatremia.
  • Resultant morbidity could be insignificant, serious, or even life-threatening.
• Research focuses on the management of hypernatremia, emphasizing a quantitative approach to the correction of the fluid imbalance (Adrogué & Madias, 2000).
• Patient-centered approach is required to determine underlying causes and effective interventions (Giddens, 2013).

Pharmacology Treatment Regimen

• The maintenance of enough body fluid volume and effective supply of this fluid between the body cells is a vital part of homeostasis (Lord, 1999).
• Osmosis determines water movement.
• Osmometry is an important part of the management of many patients (Lord, 1999).
• Osmotic process has a significant role in some therapeutic activities of drugs and its strength needs to be determined in fluids administered to patients.
• Effective treatment of hypernatremia needs a two-pronged approach (Adrogué & Madias, 2000):
  • Addressing the underlying cause.
  • Correcting the prevailing hypertonicity.

Conclusion

• Osmoregulation controls solute concentrations and balances the gain and loss of water.
• Organisms must adapt to their various environments to survive.
• In human, disturbances of osmoregulation in humans are shown through a change in serum sodium concentrations, which are responsible for hypernatremia or hyponatremia.
• Treatments should patient-centered and aim to:
  • Addressing the underlying cause.
  • Correcting the prevailing hypertonicity.

References

Adrogué, H. J., & Madias, N. E. (2000). Hypernatremia. New England Journal of Medicine, 342, 1493-1499. Web.

Agrawal, V., Agarwal, M., Joshi, S. R., & Ghosh, A. (2008). Hyponatremia and Hypernatremia : Disorders of Water Balance. Web.

Campbell, N. A., & Reece, J. B. (2007). Biology (8th ed.). San Francisco: Benjamin Cummings.

Evbuomwan, I. (2013). The role of osmoregulation in the pathophysiology and management of Severe Ovarian Hyperstimulation Syndrome. Human Fertility, 16(3), 162-167. Web.

Giddens, J. (2013). Concepts for Nursing Practice. St. Louis, MO: Mosby.

Lord, R. C. (1999). Osmosis, osmometry, and osmoregulation. Postgraduate Medical Journal, 75(880), 67-73. Web.

Sinke, A. P., & Deen, P. M. (2011). The physiological implication of novel proteins in systemic osmoregulation. The FASEB Journal, 25(10), 3279-3289. Web.