Army medical examiners were suspicious about the close proximity of the three bullet holes in Pat Tillmanâs forehead and tried without success to get authorities to investigate whether the former NFL playerâs death amounted to a crime, according to documents obtained by The Associated Press.
Membrane. Definition. noun, plural: membranes. (1) (biology) A thin layer of tissue covering a surface or lining a cavity, space or organ. (2) (biology) A cell membrane. (3) (chemistry) A thin pliable sheet of material that is permeable to substances in solution.Supplement. A biological membrane functions by protecting the surface or bodily organ.1) (biology) A thin layer of tissue covering a surface or lining a cavity, space or organ. (2) (biology) A cell membrane. (3) (chemistry) A thin pliable sheet of material that is permeable to substances in solution. Supplement. A biological membrane functions by protecting the surface or bodily organ.
In all cellular organisms, the plasma membrane is the outermost layer of a cell. It serves to separate the cell from the external environment. In prokaryotes, it is the only membrane. Eukaryotes have membrane-bound organelles. In all cases of membranes they are made of the same basic phospholipid bilayer.