Maintenance of homeostasis is important to the survival of an organism. In this lesson, you will learn what mechanisms allow the cell membrane to play a major part in maintaining homeostasis for the cell and the organism.
Definition of Homeostasis
Have you ever been really hot or really cold? What about very hungry or extremely full? Are either of those conditions comfortable for you? Of course they aren't. Most organisms want to maintain conditions that are somewhere in between the extremes. This ideal set of conditions is called homeostasis.
Homeostasis is the set of internal conditions in which an organism functions at its best. Every organism is in a constant fight to maintain homeostasis, and every single cell in the organism is a part of the battle. Every organelle in each cell is working to maintain homeostasis, including the cell membrane. The question is, how does the cell membrane aid the cell, and ultimately the overall organism, in maintaining homeostasis?
Purpose of the Cell Membrane
The job of the cell membrane is to regulate the passage of materials into and out of the cell. In order for any materials to go in or out of the cell, they must cross through the cell's membrane. The membrane decides whether that material will be allowed passage based on what is considered the optimum concentration level for that material. The cell membrane most often works specifically on the concentration of water and different types of ions. The type of cell it is will determine what the ideal concentration is for a specific material.
Structure of the Cell Membrane
The cell membrane resembles an ice cream sandwich. The outer portion, or cookie layer, is made up of a double layer of molecules called phospholipids. A phospholipid is a molecule that has a head region that carries an electric charge attached to a lipid tail portion. It resembles a balloon with a string tied to it. The lipid (tail) portion repels water and keeps it either inside or outside the cell.
The cell membrane also has molecules of cholesterol dotted at different points in the phospholipid layer. The presence of the cholesterol and short lipid tails keeps the cell membrane fluid, allowing the passage of necessary materials across its layer. This one major mechanism helps the cell with the maintenance of homeostasis.
Osmosis of Water Across the Membrane
Osmosis is the tendency for water molecules to move from where there is a higher concentration to where there is a lower one. Since cells have many other molecules inside of them, the tendency is for water to want to flow into the cell. The water wants to flow from the higher concentration, which is outside of the cell, to the lower concentration, which is inside of the cell. The cell membrane helps to regulate and slow down the flow of water into the cell. This is yet another way that the cell membrane helps maintain homeostasis.
Regulation of Ion Flow
The cell requires specific concentrations of different charged ions, such as sodium and potassium, to function properly. The cell membrane works to control the flow of ions into and out of the cell. This makes sure that the cell maintains the optimum level of ions necessary for the cell to function properly.
All of the information that we've listed details the ways in which the cell membrane helps organisms maintain optimum conditions. If these methods were not in place, the cell and the organism as a whole would have a hard time maintaining homeostasis.
This set of ideal conditions for an organism is called homeostasis. Homeostasis is the set of internal conditions in which an organism functions best. The cell membrane helps the organism in its fight to maintain homeostasis. The cell membrane assists in the maintenance of homeostasis by:
- Maintaining a fluid phospholipid structure. Phospholipids are molecules that have a head region that carries an electric charge attached to a lipid tail portion.
- Regulating osmosis, which is the tendency for water molecules to move from where there is a higher concentration to where there is a lower one.
- Maintaining specific concentrations of ions inside and outside of the cell (potassium, sodium, and others).