In multicellular organisms, growth factors, hormones, neurotransmitters, and extracellular matrix components are ... too charged to cross a cell's plasma membrane (Figure 1).

Unlike prokaryotes, eukaryotic cells also possess internal membranes that encase their organelles and control the exchange of essential cell components. Both types of membranes have a specialized ...

There are four components - or parts - of the blood: red blood cells, white blood cells, plasma and platelets. Blood carries things you need, like oxygen and glucose, and waste products ...