Biology (Mader), 10th Edition

Chapter 5: Membrane Structure and Function

Hemolysis and Crenation

Why does cell volume change in response to the environment? The membranes of blood cells, like those of any other cells, are permeable to water. Water molecules are polar but they are small enough to pass through the lipid bilayer of a membrane. Ions are not able to cross membranes unaided. Ions are also in solution with water – in other words they interact with water molecules. As a result, when ions cannot move across a membrane, water molecules diffuse until the ionic concentration is equal. If the ion concentration is very different inside and outside of cell the movement of water can cause a major change in cell size, serious cell damage, and even destruction of the cell.

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

Red blood cells are also called
A)hemoglobin.
B)monocytes.
C)white blood cells.
D)erythrocytes.
2.

Red blood cells in an isotonic solution are
A)lozenge shaped.
B)shriveled.
C)empty membraned.
D)cube shaped.
3.

Red blood cells put in a hypertonic solution will
A)not be affected in any way.
B)form linear edges.
C)shrivel and become crenated.
D)be destroyed by hemolysis.
4.

Red blood cells put in a hypotonic solution will
A)not be affected in any way.
B)form linear edges.
C)shrivel and become crenated.
D)be destroyed by hemolysis.
5.

Human erythrocytes function best in a
A)hypertonic solution.
B)isotonic solution.
C)hypotonic solution.
D)bacterial solution.
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