kidneyfxnpd2

8/3/2019 KidneyFxnPD2

1/8


2/8

Baxter PD Nurse Education

Participant Guide: PD Basics Course

Module 2: Basic Fluid Transport Principles

2007 by Baxter International 2

Movement of Fluid and Solute

Removal of fluid and solute occurs:

When fluid and solute are filtered through a semipermeable

membrane

When the blood is ultrafiltered in the glomerulus, largesubstances such as blood proteins and blood cells are keptinside the blood vessels, while the filtrate containing waterand small solutes passes through the semipermeablevessel wall into the tubules

Terminology used in filtration of fluid and solute:

Ultrafiltration fluid removal across a semipermeable membrane under pressure

Convection removing solute along with the solution's fluid (the solvent), referred to

as solvent dragHydrostatic Pressure pressure of the bloodagainst the walls of the capillaries

Glomerular filtration

Movement of fluid and solute:

Solution concentration the amount of solute and water molecules in a given solution

More water = lesssolute concentration

More solute = lesswater concentration

Random molecularmovement: high tolow concentration

Semipermeable Membrane

Semipermeable membranes have an important role:

Separates fluid spaces

Allow solutes and water to pass from theblood to the interstitial fluid to theintracellular fluid and back againdepending on two characteristics

Size of molecule

Size of pores


3/8





Key Transport Principles

The movement of solutes and water between the cellsand the extracellular fluid (ECF) are governed by thesame laws of physics that caused the dye and water tomove down the concentration gradient until theyreached equilibrium.

There exists several key transport principle:

Diffusion - solute moves from a higherto a lower solute concentration

Some solutes are not permittedto pass, and remain on their

own side of the membrane

Osmosis - movement of water across asemipermeable membrane from an area of lowersolute concentration to an area of higher soluteconcentration

Due to the unequal number of solutes pervolume of water on each side of themembrane

Osmotic pressure - the pulling pressure exerted bysolutes that are able to cross the semipermeablemembrane

The higher the concentration of solutes, thehigher the osmotic pressure exerted,resulting in osmosis

Oncotic pressure - the pullingpressure exerted by solutes that are

too large to cross thesemipermeable membrane

Results in osmosis that maybe sustained for a longerperiod of time


4/8





Fluid Management

Fluid balance is critical during peritoneal dialysis:

If placed in too concentrated an environment, the cell willshrink and die

If placed in too dilute an environment, the cell will burst anddie

Internal balance is key to survival


5/8





Check Your Learning

Match the correct term to the corresponding diagram.

Fill in the blanks:

1. Size of and size of control the movement of water and

solute.

2. More water = solute concentration while more solute =

water concentration.

3. Cell will shrink and die in too an environment.

4. Cell will burst and die in too an environment.


6/8





Crossword: This game provides a review of basic fluid transport principles.

Across

3. The combination of a solute and a solvent.7. Any substance that is dissolved in fluid.9. Removing solute along with the solution's fluid (the solvent), referred to as solvent drag."10. Fluid removal across a semipermeable membrane under pressure.11. ________ pressure of the blood against the walls of the capillaries.13. Waste product which comes from the breakdown of the protein we ingest in our diets.14. Solute moves from a higher to a lower solute concentration.15. ________ pressure is the pulling pressure exerted by solutes that are too large to cross the

semipermeable membrane.

Down1. Separation of substances through the use of a filter or membrane.2. Electrically charged molecule, like sodium or potassium.4. Movement of water across a semipermeable membrane from an area of lower solute

concentration to an area of higher solute concentration.5. Solution ________ is the amount of solute and water molecules in a given solution.6. ________ pressure is the pulling pressure exerted by solutes that are able to cross the

semipermeable membrane.8. Waste product that is formed when our muscles are used.12. The fluid in which the solute is dissolved.


7/8





Answer Key

Match the correct term its corresponding diagram.

Fill in the blanks:

1. Size of_molecule_and size of_pores_control the movement of water and solute.

2. More water = less solute concentration while more solute = less water concentration.

3. Cell will shrink and die in too concentrated an environment.

4. Cell will burst and die in too_dilute_an environment.


8/8





Crossword: This game provides a review of basic fluid transport principle.

Across3. Solution7. Solute9. Convection10. Ultrafiltration11. Hydrostatic13. Urea14. Diffusion15. Oncotic

Down1. Filtration

2. Electrolyte4. Osmosis5. Concentration6. Osmotic8. Creatinine12. Solvent

kidneyfxnpd2

Documents