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81 Cards in this Set
- Front
- Back
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Osmotic forces determine the?
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distribution of water between extracellular and intracellular fluid.
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By simple diffusion, water will tend to move from?
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regions of higher concentration to regions of lower concentration – from the regions in which the solutes are in low concentration, to the region in which the solutes are in high concentration.
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water _____ solute
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follows
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Osmolality effect is?
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The dissociation of molecules has on the concentration of solutes in body fluid
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Osmole/L formula is?
( ?? * ??) |
molar concentration * number of dissociable particles
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NaCl dissociates into Na+ and Cl- in solution, so 150 mM/L NaCl =
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300 mosm/L
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a higher osmolality represents?
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a higher solute concentration and, as a result, a lower water concentration
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Van’t hoff’s law is?
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(pie) -> π= nRTΔC
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Water will move passively from region of ____ solute concentration to region of ____ solute concentration
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low
high |
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Osmolality ISF & ICF = ? mOsm/L
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280-315 mOsm/L
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Osmolality is the same for ISF and ICF, but ?
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the concentrations of particular solutes are quite different.
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Isotonic is determined by
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effective osmolality
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Tonicity is
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defined with respect to a cell (the RBC), for which effective osmoles are solutes that are impermeable in that cell
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Isotonic solution formula:
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no gradient for water, and the RBC does not shrink
300 in and 300 out |
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Hypotonic solution formula:
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Solution has lower affective osmolarity than RBC
450 in and 150 out |
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hypertonic solution formula:
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Solution has greater affective osmolarity than RBC
150 in and 450 out |
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What are the 4 physical electrolytes and water disturbances of body fluids:
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Sweat
Water vapor (lungs) Fecal Obligate urine |
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What are the 4 pathological disturbances of body fluids:
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Blood pressure
Large fluid volume loss (i.e. hemorrhage) Cardiac output Vomiting, diarrhea |
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4 Daily disturbances of body fluids:
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Variable intake of water (drinking and from food)
Variable intake of electrolytes Loss of electrolytes and water Pathological disturbances |
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Homeostasis means ?
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We must excrete amount of solute that is taken in
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All disturbances initially change the ECF such as ?
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Overhydration = change that resulted in increased ECF
Dehydration = change that resulted in decreased ECF |
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Overhydration is the
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change that resulted in increased ECF
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Dehydration is the
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change that resulted in decreased ECF
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Disturbances which are isoosmotic _____________ effect on ICF volume
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will have no
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any disturbance that is hypoosmotic, or hyperosmotic will?
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change ICF volume (which will change concentration of things)
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Amount of solute is _________ as the concentration.
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is not the same
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Amount of solute formula is?
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concentration (osmolarity) * volume
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If the total volume of ICF = 25L and the osmolarity = 300mOsm, the
Total solute content of intracellular fluid can be found by what equation? |
volume X osmolarity
**If the cell volume decreased by 10%,( and no compensation occurred), the concentration of Na+ would increase by 10%. *** |
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Total solute Concentration formula is ??/??
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amount( moles) / volume
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Three important rules of daily disturbances:
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1. All disturbances initially change the ECF
2. Disturbances which are isoosmotic will have no effect on ICF volume; any disturbance that is hypoosmotic, or hyperosmotic must change ICF volume 3. Amount of solute is not the same as concentration. |
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If the cell volume decreased by 10%,( and no compensation occurred), the concentration of Na+ would increase by 10%. Why?
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The amount of Na (number of moles) is not changed, but the volume is, and therefore the concentration is changed
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Bodily fluid Disturbances resulting in volume changes will also change the osmolarity;but may or may not change
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the total amount of solute.
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Generally, the total amount of solute in the ____ can change, but the total amount of solute in the ____ does not change.
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ECF
ICF |
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A major role of the kidneys is to maintain ..... by regulating both __________ & __________ in the body.
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the normal concentrations of electrolytes
the amount of NaCl excreted in the urine, and the fluid volumes |
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Give the changes in bodily fluids and volumes:
Example 1. Drinking pure water ( Hypo-osmotic Over hydration) Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: Increase
Total body solute: No change Total body fluid osmolarity: Decrease ECF volume: Increase ICF volume : Increase Immediately drinking adds pure water to the ECF, making it more dilute Than the ICF, so water from ECF will now diffuse into the ICF Equilibrium: the added water is distributed to both ECF and ICF |
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Give the changes in bodily fluids and volumes:
Example 2: Blood loss (Plasma= isoosmotic) : Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: Decrease
Total body solute: Decrease Total body fluid osmolarity: No change ECF volume: Major Decrease ICF volume : No change Blood= mostly plasma, which is ECF (the cells lost are a tiny fraction of the total cell number, and therefore, a tiny fraction of the total ICF). Plasma= isoosmotic This decrease excretion of sodium which will be indicated by thirst if low enough |
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Give the changes in bodily fluids and volumes:
Example 3: adding intravenous isotonic saline Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: Increase
Total body solute: Increase Total body fluid osmolarity: No change ECF volume: Huge Increase ICF volume : No change |
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Is it possible to lose just water from the ECF?
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No, but we can do something close : Sweat
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Example 4: sweating without fluid replacement (Hyperosmotic & dehydration)
Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: Major Decrease
Total body solute: Decrease Total body fluid osmolarity: Increase ECF volume: Decrease ICF volume : Decrease |
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During sweating without fluid replacement (Hyperosmotic & dehydration), the kidneys will excrete?
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Less H2O & Na+
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Example 5:– sweating, followed by drinking pure water (Hypo-osmotic & dehydration)
Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: No change
Total body solute: Decrease Total body fluid osmolarity: Decrease (mainly salt) ECF volume: Decrease ICF volume : Increase |
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Sweat is ____tonic (about 100mOsm)
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hypo
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During sweating, followed by drinking pure water (Hypo-osmotic & dehydration), the kidneys will excrete?
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More H2O & Na+
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Sweating produces a loss of ?
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hypotonic fluid (loss of water, and some salt)
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Drinking water after sweating replaces the water lost, but not the salt, so the outcome isas if you?
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had removed some of the salt from the ECF then the water shifts into the ICF
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Example 6: Infusion of large volume of hypertonic saline solution:
Total body fluid volume Total body solute Total body fluid osmolarity ECF volume ICF volume |
Total body fluid volume: Increase
Total body solute: Major Increase Total body fluid osmolarity: Increase ECF volume: Increase ICF volume : Decrease |
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Adding a hypertonic solution (like saline) to the ECF results in
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fluid shift from the ICF into the ECF
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ECF vol. 30 minutes after intravenous infusion of 1000mL hypertonic NaCl in water
<G /S/ L> ECF vol. 30 minutes after ingestion of 1000mL of water |
Greater than:
Because ECF is increased ASAP intravenously. ECF increases a little when ingested |
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Calculate estimates to fill in the following table:
Initial / Final / Change An 80 Kg man loses 4L of sweat during a tennis match. He replaces his water loss by drinking 4 L of water but takes no salt Make the following assumptions: Initially, TBW (total body water)= 60% body weight ECF volume = 1/3 TBW Initially, ECF osmolality= 290 mOsm Osmolality of sweat= 100mOsm, and NaCl is the only solute in sweat Total body fluid |
Total body fluid
.60 TBW * 80 kg = 48 L Initial 48 L / Final 48 L/ Change: none |
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Calculate estimates to fill in the following table:
Initial / Final / Change An 80 Kg man loses 4L of sweat during a tennis match. He replaces his water loss by drinking 4 L of water but takes no salt Make the following assumptions: Initially, TBW (total body water)= 60% body weight ECF volume = 1/3 TBW Initially, ECF osmolality= 290 mOsm Osmolality of sweat= 100mOsm, and NaCl is the only solute in sweat total body solutes? |
Total body solutes
Initial: 290 mOsm * 48 L = 13920 mOsm Loss of 4 L of salt 4 L * 100 mOsm = 400 mOsm 13920 mOsm – 400 mOsm = 13520 Initial 13920 mOsm / Final 13520 mOsm / Change: - 400 mOsm loss |
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Calculate estimates to fill in the following table:
Initial/Final/Change An 80 Kg man loses 4L of sweat during a tennis match. He replaces his water loss by drinking 4 L of water but takes no salt Make the following assumptions: Initially, TBW (total body water)= 60% body weight ECF volume = 1/3 TBW Initially, ECF osmolality= 290 mOsm Osmolality of sweat= 100mOsm, and NaCl is the only solute in sweat Osmolarity |
Final: 13520mOsm /48 L = 281 mOsm
Initial 290 mOsm / Final 281 mOsm / Change: - 9 mOsm loss |
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Calculate estimates to fill in the following table:
Initial/Final/Change An 80 Kg man loses 4L of sweat during a tennis match. He replaces his water loss by drinking 4 L of water but takes no salt Make the following assumptions: Initially, TBW (total body water)= 60% body weight ECF volume = 1/3 TBW Initially, ECF osmolality= 290 mOsm Osmolality of sweat= 100mOsm, and NaCl is the only solute in sweat ICF volume |
Initial = 2/3 (67%) of TBW= 48 * .67 = 32 L
Final = 2/3 (67%) of initial TBW = 13920 * .6667 = 9280 9280 / 281 mOsm (final Osmolarity) = 33.02 L Initial 32 L / Final 33 L/ Change: 1 L |
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Kidney can excrete (in urine) water and salt (NaCl) in response to changes in
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ECF volume, and systemic osmolality
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Kidneys do what? (F,R,E)
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remove some plasma (filtration), then return most of the fluid and solutes back to the plasma (reabsorption), and excrete the rest.
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Kidney alters Na+ (in plasma) excretion to regulate?
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ECF Volume
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Kidney can also help increase or decrease systemic blood pressure (in the face of changes in ECF volume). How?
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Produces rennin which activates angiotension 2
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What can’t the Kidneys do?
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Can’t measure total solute, or ICF volume
Can’t replace H2O or salt |
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How body fluids are measured?
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Indicator – dilution technique:
Conservation of mass =: Amount in = amount out This is an application of the conservation of mass, an important principle in understanding kidney function. |
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Mass is conserved, but we are often measuring volumes and concentration
Concentration = |
Amount (mass) of solute * Volume
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ICF volume 30 minutes after a
Hemorrhage (lost volume not replaced) G S L ICF volume 30 minutes after substantial sweat loss (lost volume not replaced) |
G. left = isotonic loss of volume in ECF, and would produce no change in ICF. Right = loss of free water, and some salt, but not isotonic (hypoosmotic loss). The salt is lost from the ECF, so water will move from the ICF into the ECF, and the ICF volume will be reduced compared to the unchanged ICF volume in the left column
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ECF osmolarity 30 minutes after substantial sweat loss (lost volume not replaced)
G S L ECF osmolarity 30 minutes after substantial sweat loss (lost volume replaced by drinking pure water. |
G. The sweat that is lost is hypoosmotic: loss of water and some solute. In the case on the left, the result is that the remaining fluid in both ECF and ICF is more concentrated, meaning that the fluid has an increased osmolarity. In the case on the right, the water has been replaced, but the salt has not. The added water will dilute the solutes, and the osmolarity will be lower than in the case on the left
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ECF volume 30 minutes after a
hemorrhage (lost volume not replaced) G S L ECF volume 30 minutes after ingestion of salt (NaCl) tablets |
L. hemorrhage is an isoosmotic volume loss from the ECF. On the other hand, eating salt tablets will lead to an increased solute content in the ECF, and create an osmotic gradient for water to leave the ICF and enter the ECF. ECF volume will increase.
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ICF volume 30 minutes after
intravenous infusion of 1000mL of normal saline (isotonic solution of 0.9% NaCl in water) G S L ICF volume 30 minutes after intravenous infusion of 1000mL isotonic glucose or dextrose (5% dextrose in water)* |
L Left: isotonic saline enters the ECF compartment, with no effect on the ICF volume; Right: adding 5% glucose is equivalent, after a short time (i.e. 30 minutes) to adding pure water. Pure water is distributed to both ECF and ICF, and will therefore increase ICF volume.
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ECF osmolarity 30 minutes after intravenous infusion of 1000mL isotonic glucose or dextrose in water
G S L ECF osmolarity 30 minutes after intravenous infusion of 1000mL isotonic NaCl in water |
L Left: adding isotonic glucose or dextrose is equivalent, after a short time, to adding pure water, and this will decrease osmolarity in all compartments. Right: isotonic saline will have no effect on body osmolarity.
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ECF volume 30 minutes after
intravenous infusion of 1000mL isotonic glucose or dextrose in water G S L ECF volume 30 minutes after intravenous infusion of 1000mL isotonic NaCl in water |
L Left: Left: adding isotonic glucose or dextrose is equivalent, after a short time, to adding pure water. The pure water is distributed to both ECF and ICF, but in proportion, so most of the added volume ends up in the ICF. Right: All of the 1L IV saline enters and stays in the ECF compartment.
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ICF volume 30 minutes after
intravenous infusion of 1000mL isotonic NaCl in water G S L ICF volume 30 minutes after intravenous infusion of 1000mL hypertonic NaCl in water |
G Left: ICF volume is unchanged when isotonic NaCl is added to the ECF in the IV;. Right: hypertonic saline will create an osmotic gradient for water to leave the ICF and enter the ECF, so the ICF volume will be reduced.
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ECF osmolarity 30 minutes after intravenous infusion of 1000mL hypertonic NaCl in water
G S L ECF osmolarity 30 minutes after intravenous infusion of 1000mL isotonic glucose or dextrose in water |
G Left: addition of hypertonic NaCl will increase the osmolarity in all compartments, ECF and ICF. Right: isotonic glucose/dextrose is equivalent to pure water, and will decrease the osmolarity in all compartments.
Remember that in intravenous solutions, glucose or dextrose (dextro-rotary form of glucose) is rapidly taken up by cells and metabolized to CO2 and H20. Therefore, administering isotonic glucose or dextrose solution in physiologically equivalent to administering distilled water. |
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All of the following are characteristics of hyperosmotic overhydration except
A. increase in ECF osmolarity B. no change in ICF osmolarity C. expansion of ECF volume D. contraction of ICF volume |
B. make sure that you understand that hydration (overhydration or dehydration) refers to the ECF, while the osmolarity applies to all compartments after equilibrium has been achieved.
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In the body fluid rectangle which is ECF 7, ICF 14, 280 oMsm , determine:
Total ECF volume ___________ Total ICF volume ___________ Osmolarity of ECF ___________ Total body solute content ___________ If 1L of pure water were ingested, which of the above measurements would increase, decrease or stay the same? |
The ECF volume is 7L and the ICF volume is 14L. Osmolarity is the same for both ECF and ICF(osmolarity disturbances are always transient, and compensated for by the movement of water). The osmolarity in this figure is 280mOsm. The total solute content is the area of the rectangle, and is (osmolarity)*volume, or
280mOsm * 21L = 5,880mosm. |
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A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L.
23. Assuming a total body water of 60%, of which 1/3 is ECF, calculate the following: Before the illness Total body water (L) ECF volume (L) ICF volume (L) Total body solute (mOsm) Total ECF solute (mOsm) Total ICF solute (mOsm) |
Total body water (L) = .60 * 35kg = 21 L
ECF volume (L) = TBW/3 = 21L / 3L = 7 L ICF volume (L) = TBW – ECF = 21L – 7L = 14 L Total body solute = Initial conc. Of Na+ * TBW = 280 mOsm * 21 L = 5880 mOsm Total ECF solute = Initial conc. Of Na+ * ECF vol. = 280 mOsm * 7 L = 1960 mOsm Total ICF solute = TBS – ECFS = 5880 – 1960 = 3920 mOsm |
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A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L.
The child has lost 2L of fluid during his illness. If you could analyze this fluid (the fluid that he lost) would it be hyperosmotic, isoosmotic or hypoosmotic? (With respect to his plasma prior to the illness). |
Due to the illness, the child has a plasma [Na+] of 130. We can estimate the plasma osmolarity as 2*130 or 260 mOsm, which is much lower than the osmolarity before the illness (280mOsm). The child is now hypoosmotic. The fluid that he lost must have been hyperosmotic – he lost proportionally more solutes than water. By losing proportionally more solutes than water, the fluid than remains will have proportionally less solutes than water (compared to the state before the illness), and will be hypoosmotic.
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A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L.
A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L. As a result of the illness, what has happened to the solutes in the body fluid compartments? Increased, decreased, stayed the same? Total body solute ECF total solute ICF total solute |
ECF volume (L) - Decreased
ICF volume (L) -increased We know that the initial loss of fluid was from the ECF –fluid loss or gain is always initially with respect to the extracellular fluid. The diagram shows the ECF volume during the illness is less than it was before the illness. However, the diagram also shows that there has been an increase in the ICF volume. This increase is due to a shift of water from the ECF, to the ICF. Water follows an osmotic gradient and this shift means that the ECF was hypoosmotic due to the illness. This results in an osmotic gradient that results in water moving into the cells, and therefore the total ICF volume increases. |
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A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L.
The child has lost fluid, and needs some type of fluid replacement. If you gave the child 2L of water, what would happen to the following measurements ICF volume (increase, decrease or stay the same) ECF volume (increase, decrease or stay the same) Plasma osmolarity (increase, decrease or stay the same) |
ICF volume (increase,)
ECF volume (increase,) Plasma osmolarity (decrease) The child has lost fluid, but is also hypotonic. Pure water will be distributed to both ECF and ICF, in proportion to the volumes after 2 days – ECF is approximately 1/5 of the total fluid, so only 1/5 of the 2L will enter the ECF. This is clearly inadequate, given the huge loss of fluid from vomiting and diarrhea. In addition, the pure water will depress the osmolarity even more. |
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A child (body weight = 35Kg) develops gastroenteritis with vomiting and diarrhea. Over a 2 day period he also loses 2Kg of weight (assume this is a fluid volume loss of 2L, and not a tissue mass loss). However, his plasma [Na+] is 130mm/L, down from his initial value of 140mm/L.
Instead of giving the child water, what would happen to the same measurements if you gave the child 2L of .9% saline? ICF volume (I/D/S) ECF volume (I/D/S) Plasma osmolarity (I/D/S) |
ICF volume - decrease
ECF volume - increase Plasma osmolarity - increase? 0.9% saline has an osmolarity of about 290mOsm. This is slightly greater than the osmolarity of this child after the 2 days of illness (his plasma osmolarity is about 260, or 2* plasma [Na+] ). The 2L will be distributed in the ECF, plus some water will also be drawn from the intracellular fluid into the extracellular fluid, due to the slightly higher osmolarity of the saline. One could in theory give an even more hypertonic solution to help correct the fluid and sodium loss, but in most cases normal saline is sufficient when coupled with normal renal compensation |
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You dissolve 10g of glucose in enough pure water to make 250 ml of solution (“solution #1”). After stirring well, you take 20mL of solution #1 and add 980 ml of pure water to make solution #2.
What is the glucose concentration in solution #1? Solution #2? |
Remember, amount/volume = concentration
solution #1: amount = 10g volume =250ml, concentration = 10g/ 250ml = .040g/ml you could also convert the grams to mg, = .040g/ml * 1mg/1000g = 40mg/ml solution #2, amount of glucose = 20ml * concentration of glucose in solution 1 = 20 ml * 40mg/ml = 800mg of glucose Since you will now add 980ml of water, the new volume for solution #2 will be 1000ml And the new concentration is 800mg/ 1000ml = 0.8mg/ml Glucose concentrations are often given in dL 1dL= 100ml Solution 2 in dl would be .8mg/ml * 100ml/dl or 80mg/dl |
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During a body fluid compartment measurement experiment, Evans blue dye is injected into a vein. Evans blue dye has the following characteristics: it mixes evenly through all of the plasma, but does not enter blood cells, and does not escape from the blood. However, in this case, but some of the Evans blue indicator dye is accidentally injected subcutaneously into the interstitial space.
As a result of this mistake the ________ volume you calculate will _______ the true value A. ICF underestimate B. plasma underestimate C. plasma overestimate |
C. The Evans blue dye is normally used to measure plasma volume, because the dye is soluble in the plasma, but does not enter the cells (such as the red blood cells), and does not exit the blood vessels.
Normally, plasma volume would be calculated by : (amount of dye added )/ (concentration in plasma) In this experiment, however, some of the dye was lost be entering the interstitium, so the concentration in the plasma will be reduced. The volume calculated will then be an overestimate of the true volume |
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Mannitol is a non-toxic monosaccharide that readily crosses the vascular endothelium but does not cross plasma membranes. Mannitol does not occur naturally in the body and it is metabolized very slowly. These properties make mannitol a suitable indicator to measure:
A. total body water volume B. extracellular fluid volume C. plasma volume D. interstitial fluid volume E. blood volume |
B. Since mannitol crosses the vascular endothelium, it will be distributed throughout the interstitial fluid in addition to plasma, and can therefore be used to measure ECF volume
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One gram of mannitol was dissolved in a small volume of isotonic saline and the solution administered intravenously into a patient. Thirty minutes later, a sample of the patient’s plasma is obtained and is found to contain mannitol in a concentration of 80 micrograms per mL. From this information, it can be calculated that the patient’s:
A. ECF volume is 12.5L B. Total body water (TBW) is 25L C. ICF volume is 6.25L D. plasma volume is 2.5L E. hematocrit is 35% |
A
Amount in (mass of mannitol) = 1g Final concentration = 80μg/mL Volume = (amount in )/ (concentration) = 1 g / ( 8x10-5 g/ml) = 12.5L (make sure that you pay careful attention to unit conversions) What fluid compartment was measured? From the question above, you know that mannitol is measuring the ECF volume. |
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You have a sample of a fluorescently tagged plasma protein and you wish to estimate total blood volume of a patient. The plasma protein is confined to plasma, does not enter blood cells, and the fluorescent tag allows you to measure the concentration of this protein. You inject 60mg of this protein into a vein. After an appropriate time to allow compete mixing, you take a sample of the blood, and find that the plasma concentration of the protein is 0.02mg/ml. Assuming that the hematocrit of this patient is 45%, what is the blood volume?
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Calculating total blood volume from plasma volume:
Blood volume = plasma volume/ (1-hematocrit) Blood volume = 3L / (.55) =5.4L Since the protein remains within the plasma and does not enter into any of the blood cells, the protein will be distributed only within the plasma volume, and so the volume measured will be plasma volume. The amount in (mass) = 60mg Volume = (amount in)/ (concentration) =60mg/(0.02mg/ml) = 3000ml, or 3L, of plasma Blood consists of plasma, plus the cellular portions of blood. These cellular portions of blood are measured as the hematocrit, the fraction of total blood volume taken up by cells (non plasma). The hematocrit in this case is 45%, so that means that 45% of the blood volume is cellular, and 55% of the blood volume is plasma |
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Kidney alters water excretion to regulate?
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osmolarity
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Kidney can also help increase or decrease ______in the face of changes in ECF volume
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systemic blood pressure
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