The body has over 75 trillion cells, each as individual as you are. They
each perform a specific function, while all working together in harmony to
form a social (body) consciousness. In other words, all your cells depend
upon each other and work together for the life and functioning of the body.
As the microcosm is a reflection of the macrocosm, a body is a reflection
of each of its cells, each being a society unto itself. Each cell is actually like a
completely self-sustaining city, taking care of all its own functions, with two
exceptions. All cells need an external source of energy (or connection) to this
world, and they all need to eliminate their wastes. Let’s examine the “city” or
“universe” of the cell.
There are many different systems or structures within a city (like the
highway department, for instance) that perform specific functions aimed at
the survival and productivity of that city. The same is true within each cell. It
has a courthouse (nucleus) where all the records (genetic information) are
kept. Within the courthouse (nucleus) you have government employees
(nucleoli) who carry out the daily activities and needs that are required for the
“men in the field” (ribosomes). All of the above determine the individuality
of the cells and their functions.
The atmosphere and the living substance of a cell is called cytoplasm.
The city (or cell) is surrounded and protected by a wall and gate system called
the plasma membrane or cell wall membrane. This “cellular wall” has
gatekeepers that allow or disallow substances into the cell.
The courthouse (nucleus) is also surrounded by a protective and
functional wall called the nuclear envelope. There are workers that carry
information (substances) from the courthouse (nucleus) to the city and from
the city (body or cytoplasm) to the nucleus. These workers are called the
endoplasmic reticulum (ER for short).
Extra-cellular substances = substances outside the cells
Intra-cellular substances = substances inside the cells
The Golgi apparatus is named for Camillo Golgi (individuals who
discover things like to put their names on them). Golgi was an Italian
histologist who uncovered the function of these curved stacks of membrane-
bound sacs within cells, which act as factories. They collect, modify, package
and distribute the proteins and lipids that are manufactured by the ER. These
proteins are present in large amounts in the pancreas, salivary glands, liver,
and other organs.