Crenation
Encyclopedia
Crenation is the contraction of a cell after exposure to a hypertonic solution, due to the loss of water through osmosis
. The word is from the Latin "crenatus" meaning scalloped or notched, and is named for the scalloped-edged shape the cells take on when crenated.
Crenation occurs because in a hypertonic environment, (that is, the cell has a lower concentration of solutes and, therefore, higher water potential than the surrounding extracellular fluid), osmosis
(the diffusion
of water
) causes a net movement of water out of the cell, causing the cytoplasm to decrease in its volume. As a result the cell shrinks and forms abnormal notchings around its edges.
The effects of crenation are especially visible in red blood cells, or erythrocytes, as they become distorted in shape rather than maintaining the usual disc-like shape with the dimple that the blood cell normally has. Instead, the red blood cell looks as if it has legs extending from a smaller central area, like a spiked ball.
Plasmolysis
is the term which describes plant cells when the cytoplasm shrinks from the cell wall in a hypertonic environment. In plasmolysis, the cell wall stays intact, but the plasma membrane shrinks and the chloroplasts of the plant cell concentrate in the center of the cell.
In an isotonic solution, the concentration of the solute in the solution outside of the cell equals the concentration of the solute inside of the cell so there is no net change in the concentrations of either solution.
Osmosis
Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides...
. The word is from the Latin "crenatus" meaning scalloped or notched, and is named for the scalloped-edged shape the cells take on when crenated.
Crenation occurs because in a hypertonic environment, (that is, the cell has a lower concentration of solutes and, therefore, higher water potential than the surrounding extracellular fluid), osmosis
Osmosis
Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides...
(the diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
of water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
) causes a net movement of water out of the cell, causing the cytoplasm to decrease in its volume. As a result the cell shrinks and forms abnormal notchings around its edges.
The effects of crenation are especially visible in red blood cells, or erythrocytes, as they become distorted in shape rather than maintaining the usual disc-like shape with the dimple that the blood cell normally has. Instead, the red blood cell looks as if it has legs extending from a smaller central area, like a spiked ball.
Plasmolysis
Plasmolysis
Plasmolysis is the process in plant cells where the cytoplasm pulls away from the cell wall due to the loss of water through osmosis. The reverse process, cytolysis, can occur if the cell is in a hypotonic solution resulting in a higher external osmotic pressure and a net flow of water into the cell...
is the term which describes plant cells when the cytoplasm shrinks from the cell wall in a hypertonic environment. In plasmolysis, the cell wall stays intact, but the plasma membrane shrinks and the chloroplasts of the plant cell concentrate in the center of the cell.
In an isotonic solution, the concentration of the solute in the solution outside of the cell equals the concentration of the solute inside of the cell so there is no net change in the concentrations of either solution.
External links
- Image from Cornell.edu
- Crenation at medical-dictionary.thefreedictionary.com