Maintaining Equilibrium

Besides protecting the cell, the cell membrane plays a large role in maintaining equilibrium.


© Biezl, via Wikimedia Commons 
A6.6 A cell moving toward equilibrium
Equilibrium is the idea that everything is balanced inside and outside the cell. This means the cell membrane works toward keeping all the materials, elements, particles, and compounds at the same concentration inside and outside of the cell.

The cell membrane also needs to maintain homeostasis. Homeostasis means staying the same or not changing. This means the cell membrane is trying to keep the concentration of everything inside the cell the same at all times. Some particles have a higher concentration inside of the cell due to what they are used for. For example, root cells in plants will have a larger nutrient concentration on the inside of the cell than outside the cell. Keeping this higher concentration inside the cell is the cell membrane maintaining homeostasis but not equilibrium.

The cell membrane is trying to keep both equilibrium and homeostasis. It wants to have the same concentration of most particles on either side of the membrane, but it also wants to stay the same. The particles that are needed more on the inside are brought inside despite equilibrium.

A6.7 Root vegetables have a high concentration of nutrients.

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. What is the difference between equilibrium and homeostasis?
Equilibrium means keeping the concentrations of particles the same on either side of the cell membrane. Homeostasis means keeping the concentrations the same as they always are, even if that means they are not equal. For example, a cell membrane will keep the concentration of salt equal on both sides (equilibrium) but will keep a higher concentration of nutrients inside the cell (homeostasis).