Biology Chapter on Tonicity

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Questions and Answers

What is tonicity primarily determined by?

pH level and concentration

Temperature and pressure

Volume and solute type

Concentration and permeability of solute (correct)

What happens to red blood cells in a hypotonic solution?

They become crenated

They remain unchanged

They shrivel and lose water

They absorb water and may burst (correct)

Which solution would have the same solute concentration as the cytosol?

Supersaturated solution

Hypertonic solution

Isotonic solution (correct)

Hypotonic solution

What is hemolysis?

The bursting of cells and release of hemoglobin Signup and view all the answers

Why must pharmaceutical solutions for delicate membranes be isotonic?

To prevent irritation and damage to tissues Signup and view all the answers

What is the freezing point depression of isotonic solutions in comparison to lachrymal secretion?

-0.52°C Signup and view all the answers

What is the result of a cell being placed in a hypertonic solution?

The cell loses water and becomes crenated Signup and view all the answers

Which method can be used to render a drug solution isotonic?

Cryoscopic method Signup and view all the answers

What is the primary purpose of adjusting tonicity in pharmaceutical solutions?

To ensure the solution is isotonic with blood serum Signup and view all the answers

In the freezing point lowering method, how much sodium chloride is needed if the freezing point lowering of a 1% solution of apomorphine hydrochloride is known to be 0.08°?

0.76 g Signup and view all the answers

When using the sodium chloride equivalent method, what is the contribution of atropine sulfate to the NaCl equivalent in a solution of 30 ml containing 0.6 g of atropine sulfate?

0.072 g Signup and view all the answers

What freezing point lowering is necessary to render the apomorphine hydrochloride solution isotonic with blood serum, given a current freezing point lowering of 0.08°?

0.44° Signup and view all the answers

How is the amount of sodium chloride equivalent determined for a drug?

It is calculated based on the osmotic effect of the drug Signup and view all the answers

In the example presented, what was the total amount of sodium chloride needed to make the solution isotonic after accounting for the contribution of atropine sulfate?

0.198 g Signup and view all the answers

What is the freezing point lowering of a 1% sodium chloride solution?

0.58° Signup and view all the answers

Which method for tonicity adjustment is based on calculating the sodium chloride equivalent of a drug?

Sodium chloride equivalent method Signup and view all the answers

Study Notes

Tonicity

Tonicity is a solution's ability to affect fluid volume and pressure within a cell.
It depends on solute concentration and permeability.

Isotonic Solution

An isotonic solution has the same solute concentration as the cytosol.
Normal saline is an example of an isotonic solution.

Paratonic Solutions

Paratonic solutions are further categorized as either hypotonic or hypertonic.

Hypotonic Solution

A hypotonic solution has a lower concentration of non-penetrating solutes than the cytosol.
Cells placed in a hypotonic solution absorb water, causing them to swell and potentially burst (lyse).

Hypertonic Solution

A hypertonic solution has a higher concentration of non-penetrating solutes than the cytosol.
Cells placed in a hypertonic solution lose water, causing them to shrink and shrivel (crenate).

Red Blood Cells in Different Solutions

If red blood cells are placed in a hypertonic solution, water moves out of the cells, causing them to shrink.
If red blood cells are placed in a hypotonic solution, water moves into the cells, causing them to swell and potentially burst (hemolysis).

Pharmaceutical Solutions

Pharmaceutical solutions used in eyes or nose should be isotonic to avoid irritation, especially with large volumes.
Solutions should also be buffered at the desired pH.

Methods of Adjusting Tonicity

Methods exist to calculate the amounts of specific substances (like sodium chloride or dextrose)
This adjustment is to make solutions isotonic.

Cryoscopic Method

Sodium chloride or another substance may be added to a solution to lower the freezing point to be isotonic to body fluids (-0.52°C).
Lachrymal fluid serves as a reference point during this method.

Example Calculation (using Sodium Chloride and Apomorphine Hydrochloride)

Specific calculations use proportions to determine necessary amounts of sodium chloride.
Additional considerations using 1% solutions are used in these types of calculations.

B - Sodium Chloride Equivalent Method

A method to determine the quantity of sodium chloride to balance another solution by matching the osmotic effect.
Sodium chloride equivalents are calculated for comparison for different drugs.

Detailed tables providing molecular weights, ions, and equivalents are available to assist in complex calculations of adjusting tonicity.

Example Calculation (using Atropine Sulfate and NaCl)

Calculations are presented using atropine sulfate and sodium chloride to demonstrate the process of balancing tonicity.

Additional substances (Alternative to NaCl)

Other substances may also be used, such as boric acid to adjust isotonicity, specifically in ophthalmic solutions.
This choice is often made for their buffering and anti-infective properties.

Example Calculation (using phenacaine hydrochloride, chlorobutanol, and boric acid)

Complex calculations demonstrating the process of adjusting ophthalmic prescriptions using different solutions and the equivalent quantities for matching tonicity.

Determining Tonicity of Commercial Products

Guidance is given to determine if commercial products (like ophthalmic solutions, infusions, etc.) are hypotonic, hypertonic or isotonic.

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Description

Explore the concepts of tonicity, including isotonic, hypotonic, and hypertonic solutions. Understand how these solutions affect red blood cells and their behaviors in different environments. This quiz will test your knowledge on fluid dynamics in biological systems.