osmotic pressure

Examples of osmotic pressure in the following topics:

• Osmotic Pressure

  • The height difference between the two sides can be be converted into pressure to find the osmotic pressure exerted on the solution by the pure solvent.
  • The osmotic pressure is the pressure required to achieve osmotic equilibrium.
  • The osmotic pressure (II) of an ideal solution can be approximated by the Morse equation:
  • What is the osmotic pressure of a 1.35 M solution of NaCl at 25 oC?
  • Discuss the effects of a solute on the osmotic pressure of a solution

• Capillary Dynamics

  • Hydrostatic and osmotic pressure are opposing factors that drive capillary dynamics.
  • Oncotic or colloid osmotic pressure is a form of osmotic pressure exerted by proteins in the blood plasma or interstitial fluid.
  • Hydrostatic pressure is the force generated by the pressure of fluid within or outside of capillary on the capillary wall.
  • However, because large plasma proteins, especially albumin, cannot easily cross through the capillary walls, their effect on the osmotic pressure of the capillary interiors will to some extent balance the tendency for fluid to leak from the capillaries.
  • Describe hydrostatic pressure and osmotic pressure, the factors of capillary dynamics

• Osmotic Pressure

  • The correct osmotic pressure in the culture medium is essential for the survival of the cells.
  • Osmotic pressure is an important factor that affects cells.
  • Osmoregulation is the homeostasis mechanism of an organism to reach balance in osmotic pressure.
  • Having the correct osmotic pressure in the culture medium is essential.

• Introduction to Osmoregulation

  • Osmosis is the diffusion of water across a membrane in response to osmotic pressure caused by an imbalance of molecules on either side of the membrane.
  • Isotonic cells have an equal concentration of solutes inside and outside the cell; this equalizes the osmotic pressure on either side of the semi-permeable membrane.
  • When disease or injury damage the mechanisms that regulate osmotic pressure, toxic waste or water may accumulate, with potentially dire consequences.
  • Water movement due to osmotic pressure across membranes may change the volume of these fluid compartments.
  • Because blood plasma is one of the fluid components, osmotic pressure can directly influence blood pressure and other medical indicators.

• Regulation of Glomerular Filtration Rate

  • The filtration constant is based on the surface area of the glomerular capillaries, and the hydrostatic pressure is a pushing force exerted from the flow of a fluid itself; osmotic pressure is the pulling force exerted by proteins.
  • Changes in either the hydrostatic or osmotic pressure in the glomerulus or Bowman's capsule will change GFR.
  • Increased osmotic pressure in the glomerulus is due to increased serum albumin in the bloodstream and decreases GFR, and vice versa.
  • Under normal conditions, albumins cannot be filtered into the Bowman's capsule, so the osmotic pressure in the Bowman's space is generally not present, and is removed from the GFR equation.
  • In certain kidney diseases, the basement membrane may be damaged (becoming leaky to proteins), which results in decreased GFR due to the increased Bowman's capsule osmotic pressure.

• Osmoregulators and Osmoconformers

  • Persons lost at sea without any fresh water to drink are at risk of severe dehydration because the human body cannot adapt to drinking seawater, which is hypertonic (having higher osmotic pressure) in comparison to body fluids.
  • These fish are incapable of osmotic regulation in the alternate habitat.
  • In relatively hypotonic (low osmotic pressure) fresh water, their skin absorbs water (see [a] in ).
  • Sharks are "ureotelic" animals that secrete urea to maintain osmotic balance.
  • Salmon physiology responds to freshwater and seawater to maintain osmotic balance

• Osmotic Pressure

  • Osmotic pressure is the pressure which must be applied to a solution to prevent the inward flow of water across a semipermeable membrane.
  • Osmotic pressure is the pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.
  • It is also defined as the minimum pressure needed to nullify osmosis.The phenomenon of osmotic pressure arises from the tendency of a pure solvent to move through a semi-permeable membrane and into a solution containing a solute to which the membrane is impermeable.
  • Removal of water and addition of salt to meat creates a solute-rich environment where osmotic pressure draws water out of microorganisms, thereby retarding their growth.

• Movement of Fluid Among Compartments

  • Hydrostatic pressure is generated by the contractions of the heart during systole.
  • The osmotic pressure drives water back into the vessels.
  • At the arterial end of a vessel, the hydrostatic pressure is greater than the osmotic pressure, so the net movement favors water and other solutes being passed into the tissue fluid.
  • At the venous end, the osmotic pressure is greater, so the net movement favors substances being passed back into the capillary.
  • Oncotic pressure exerted by proteins in blood plasma tends to pull water into the circulatory system.

• Bulk Flow: Filtration and Reabsorption

  • Capillary fluid movement occurs as a result of diffusion (colloid osmotic pressure), transcytosis, and filtration.
  • The movement of materials across the capillary wall is dependent on pressure and is bidirectional depending on the net filtration pressure derived from the four Starling forces.
  • When moving from the bloodstream into the interstitium, bulk flow is termed filtration, which is favored by blood hydrostatic pressure and interstitial fluid oncotic pressure.
  • When moving from the interstitium into the bloodstream, the process is termed reabsorption and is favored by blood oncotic pressure and interstitial fluid hydrostatic pressure.
  • Modern evidence shows that in most cases, venular blood pressure exceeds the opposing pressure, thus maintaining a positive outward force.

• Other Hormonal Controls for Osmoregulation

  • Thus, via the RAAS, the kidneys control blood pressure and volume directly.
  • Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance.
  • As sodium is always reabsorbed by active transport and water follows sodium to maintain osmotic balance, aldosterone manages not only sodium levels, but also the water levels in body fluids.
  • ANP affects salt release; because water passively follows salt to maintain osmotic balance, it also has a diuretic effect.
  • The renin-angiotensin-aldosterone system increases blood pressure and volume.