1. Concentration gradient is the difference in the concentration of a chemical between one
side of the plasma membrane and the other. (eg. Inside and outside the membrane)
2. Electrical gradient is the difference in concentration of ions between one side of the plasma
membrane and the other.
3. Together, these gradients make up an Electrochemical gradient
Plasma Membrane
Relevant to hematology, the membrane is also the location of cell surface glycoprotein and glycolipid
molecules (surface markers or antigens) used for blood cell identity.
Each type of blood cell expresses a unique array of surface markers at different stages of differentiation.
Monoclonal antibodies are used to identify a blood cell’s surface antigens using flow cytometry. An
international nomenclature was developed, called the cluster of differentiation, or CD, system, in which
a CD number was assigned to each identified blood cell surface antigen.
Over 350 CD antigens have been identified on blood cells.
The CD nomenclature allows scientists, clinicians, and laboratory practitioners to communicate in a
universal language for hematology research and diagnostic and therapeutic practice. The red blood cell
membrane has been the most widely studied and serves as an example of a cell membrane.