by Steve Christensen

Created on: July 20, 2010

It’s one of those biological hierarchies we all learned in high school science class: Complex molecules aggregate to form cells; cells cooperate to form tissues; tissues organize to form organs; a group of organs comprises an organ system; and an assemblage of organ systems constitutes an organism.

So it is with humans, who are, of course, organisms. The conglomeration and interplay of various organ systems is what makes Homo sapiens the fascinating beings we are…and the tendency for these organ systems to malfunction is what justifies the existence of physicians, medicine men, shamans, and others of their ilk.

In fact, there are those within the healers’ realm whose lifelong attentions are focused on the function – and the malfunction – of a specific organ system, or even a single organ or tissue within an organ system.

Anatomy and physiology – two fields of knowledge that partially encompass the nature of organ systems – are complex and fluid disciplines. Practitioners of the healing arts spend their entire lives plumbing the depths of these sciences; therefore, while the uninformed or casual reader can gain a basic understanding of organ systems relatively quickly, extensive understanding only comes from dedicated study.

With that in mind, what follows is a primer on human organ systems and their basic functions.

The Integumentary System (Skin and Associated Structures)

The skin is the largest organ in the body. It separates us from a hostile environment, helps to provide recognizable form (important for attracting mates and expediting other social interactions), aids in excretion of certain toxins and wastes, and helps to stabilize internal temperatures.

Normal skin is composed of two layers: the outer layer, or epidermis, which has four or five layers depending on the skin’s location; and the dermis, a two-tiered layer of connective tissue, elastic fibers, blood vessels, and cells.

The epidermis is a layer of skin cell maturation and renewal; it is also responsible for the various shades of pigmentation that are typical of human skin. The dermis contains the hair follicles and the sebaceous and sweat glands, along with their ducts.

Skin can be thick or thin and hairy or hairless. Skin appendages (sweat and oil glands, nails, and hairs) and sensory glands (for detecting pressure, temperature, pain, etc.) vary in their concentrations throughout the integument, depending on where the skin is located on the

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