Effects of Osmosis on Life Osmosis- diffusion of water

through a selectively permeable membrane.

There are 3 types of solutions:IsotonicHypertonicHypotonic

Isotonic Solution Solutions that contain the same

concentration of solutes as the cytoplasm are called isotonic (or normal saline) solutions.

There is no net movement of water either into or out of the cell.

Cells maintain their normal shape.

WATCH VIDEO OF BLOOD IN AN ISOTONIC SOLUTION

Isotonic Solution

Isotonic: The concentration of solutes in the external solution is equal to the concentration of solutes inside the cell.

Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

Hypertonic Solution A hypertonic solution is a solution that

contains more (hyper) solutes than the cytoplasm of the cell.

Has less water than the cell and water moves out of the cell. The cells shrink.

WATCH VIDEO OF NORMAL RBCs SUBJECTED TO A HYPERTONIC SOLUTION

Hypertonic Solution

Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)

Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis/crenation)!

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

shrinks

Hypotonic Solution A hypotonic solution contains

less solute (thus, more water) than the cytoplasm of the cells.

The water will move into the cells resulting in the swelling and lysis of the cells. 

WATCH VIDEO OF CRENATED RBCs SUBJECTED TO A HYPOTONIC SOLUTION

Hypotonic Solution

Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)

Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

Let’s take a closer look!

http://www.coolschool.ca/lor/BI12/unit4/U04L06/rbc.html

What type of solution are these cells in?

A CB

Hypertonic Isotonic Hypotonic