Total osmolarity of blood? Curious about water weight vs. biological

In summary, plasma osmolality is the concentration of electrolytes in the "plasma solvent". This measurement is used to determine the health of a person, as well as the rate of recovery after a blood donation.
  • #1
pa5tabear
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Total "osmolarity" of blood? Curious about water weight vs. biological

I've seen plasma osmolality described on wikipedia:

http://en.wikipedia.org/wiki/Plasma_osmolality

This looks at the concentration of electrolytes in the "plasma solvent". However, plasma is the liquid of the blood, with cells removed.

I'm curious about the concentration of blood cells AND electrolytes in the "plasma solvent". Has anyone seen information on this?
 
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  • #2


In what units do you want blood cells concentration? Electrolytes are listed as molarity oir equivalents, these don't make much sense for erythrocytes or white blood cells.
 
  • #3


Borek said:
In what units do you want blood cells concentration? Electrolytes are listed as molarity oir equivalents, these don't make much sense for erythrocytes or white blood cells.

I suppose units of cells/liter, or gram/liter.

I gave blood recently and I'm curious how that would affect my whole body's blood concentrations, the rate of recovery, and the amount of food energy required to make that recovery. I suspected that my cardiovascular performance was affected 24 hours later, but I want to see if there's a basis for that suspicion.
 
  • #4


Back of the envelope approach would be that you have around 5L of blood, assuming you donated 0.4 L and blood was immediately diluted back to 5L, new concentrations would be [itex]\frac{5-0.4}{5}=0.92[/itex] or 92% of the original. But it doesn't work this way - I suppose electrolytes are replaced almost instantly, as their concentration (just like pH) must be kept in a very narrow range. However, erythrocytes need weeks to be replenished and their amount is variable, so the 92% number can be reasonably accurate.
 
  • #5


Borek said:
Back of the envelope approach would be that you have around 5L of blood, assuming you donated 0.4 L and blood was immediately diluted back to 5L, new concentrations would be [itex]\frac{5-0.4}{5}=0.92[/itex] or 92% of the original. But it doesn't work this way - I suppose electrolytes are replaced almost instantly, as their concentration (just like pH) must be kept in a very narrow range. However, erythrocytes need weeks to be replenished and their amount is variable, so the 92% number can be reasonably accurate.

Do you know about the energy required to replenish? I assume we'd calculate the concentration of erythrocytes and other molecules the body produces, then calculate the enthalpy of formation for the total cell growth, then figure out the conversion factor to attain that amount of energy from chemical energy of food.

I'm not sure how to calculate these things, though.
 
  • #6


You don't need concentrations, you can easily calculate number of erythrocytes. And I doubt anyone will calculate "enthalpy of formation" for a cell. They are not identical.
 

1. What is osmolarity?

Osmolarity is a measure of the concentration of solute particles in a solution. It is expressed as the number of osmoles (Osm) of solute per liter (L) of solution.

2. How is the total osmolarity of blood calculated?

The total osmolarity of blood is calculated by adding up the concentrations of all solutes present in the blood, including electrolytes, proteins, and other molecules. This measurement is important for maintaining the proper balance of fluids in the body and ensuring proper cell function.

3. What is the significance of the total osmolarity of blood?

The total osmolarity of blood is essential for maintaining the proper distribution of water and nutrients throughout the body. It also helps regulate blood pressure and ensures that cells maintain their shape and function correctly. Deviations from the normal range of osmolarity can lead to health problems such as dehydration or overhydration.

4. How does water weight affect total osmolarity of blood?

Water weight, or the amount of water in the body, can significantly impact the total osmolarity of blood. When there is an imbalance in the amount of water in the body, it can cause changes in the concentration of solutes and alter the osmolarity of blood. This can lead to health issues such as edema or electrolyte imbalances.

5. What is the difference between water weight and biological osmolarity?

Water weight refers to the amount of water in the body, while biological osmolarity refers to the total concentration of solutes in the body. While water weight can affect the osmolarity of blood, biological osmolarity takes into account all solutes present in the body, including proteins, ions, and other molecules. Maintaining a balance between water weight and biological osmolarity is crucial for proper bodily functions.

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