Membranes III: Significance of the State of Membrane for the Specific Cell Functions

Overview

Plasma membrane is usually considered to be an important supporting system; however, its role in the control and modulation of membrane functional units (e.g., ion channels, receptors) and therefore in the determination of characteristic cellular features is frequently neglected. Membrane has to be understood as a dynamic structural and functional system.

Flow of water across the plasma membrane is one of the essential homeostatic mechanisms. Water can cross the membrane by diffusion across the lipid bilayer or it can move via selective channels.

Existence of those channels (aquaporins) was identified only in the eighties of the twentieth century.

Intercellular communication in the vertebrate CNS is provided mainly by specialized intercellular contacts - chemical synapses. Beside them, electrical synapses, which are derivates of gap junctions, play an important role. Electrical synapses participate in the synchronization of large neuronal populations and they mediate communication between neurons and glial cells and thus they help to regulate electrical and metabolic activity of the nervous tissue.

Key words:
variability membrane, aquaporin, apoptosis, mitochondria, presynaptic element, gap junctions, electrical synapse.