STRUCTURE

Anatomical, Physiological and Chemical Basis of the Structure

Anatomical, Physiological and Chemical Basis of the Structure

Q.1.

Ans.

The term cell is used to refer to the point at which, in any contingency table, a row and a column intersect. Thus, a contingency table relating to two binary variables will have four cells. The cell is the structural and functional unit of all living organisms (Fawcett, 1994). In the study of cells, its classification is of prime importance. Cells can be broadly classified into two types: prokaryotic (Greek: before the nucleus) cells and eukaryotic cells (Greek: new nucleus). The prokaryotic cell differs from the eukaryotic cell by the absence of a true nucleus (double membrane bound structure containing genetic information), membraned organelles (subcellular structures having a distinct function), and has a 70 S ribosome.

The human cell is a typical animal cell and is partitioned into two major components: protoplasm and nucleus enclosed within a cell membrane. Although different human cells have specific functional and structural characteristics, their basic structure is similar. The cell membrane is made up of lipids (phospholipids, gly—colipids, and steroids) and different membrane proteins.

Q.2

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Homeostasis is a concept used to describe the tendency of living entities to maintain a stable, steady internal state despite change, disturbances, and variations in their external environments. Although its roots are found in the natural sciences, the concept has been used by social scientists to describe the tendency of social collectives—social systems, formal and informal organizations—to maintain their identities, in whole or in part, in the face of planned or unplanned change forces. The word homeostasis is derived from two Greek words (homo: “same” and stasis: “state”). Its literal meaning is “same” or “steady state of being.” Both the idea and nominal concept have their roots in the field of physiology. The Frenchman Claude Bernard (1813-1878) was the first to articulate the idea of homeostasis.

The term itself was later coined by Walter Cannon in 1932. Physiologists used homeostasis to describe the ability of the body to maintain a stable internal state despite environmental variations and disturbances (e.g., temperature changes in the environment). It is argued that this tendency toward the maintenance of a homeostatic or “steady state” of equilibrium is attributed to an ability of the human body to sense and adjust to environmental changes. Working in conjunction with the brain, the body is endowed with multiple feedback inhibition mechanisms that enable it to counteract those influences that would lead it toward disequilibrium. As a result, these mechanisms create for the body what is known as homeostatic stability. (Herlihy and Maebius, 2002)

With its reference to system change, stability, and maintenance, homeostasis is one of many concepts associated with systems theory. A system is any set or group of interrelated elements that when considered together constitute an identifiable entity in which a change in one part of the elements affects some or all of the elements of the system. Such systems may be natural (human body, the cell, the solar system, ...