Читать книгу Your Key to Good Health - Elaine Hruska - Страница 15

We exist within our bodies in a wet world, water comprising 70-80 percent of our being. Flowing between all the cells, interstitial fluid bathes these cells with life-giving substances. Its clear, colorless liquid carries such microscopic particles as white blood cells, proteins, and other substances vital to the life of the cell. Blood capillaries also exude fluid into tissues, but not all this fluid returns to the blood, thus creating an accumulation, or excess, of tissue fluid. Collecting this excess fluid from between the cells and eventually returning it to the body’s circulation is the purpose for this vast lymphatic network, with its miles of tubes and channels of interconnected vessels. When too much of the interstitial fluid accumulates, the lymphatic vessels, as stated previously, channel it through a series of closed-end tubules. Now it is called lymph, a word derived from the Latin lympha, meaning “clear water” or “spring water.”

Figure 3

Drainage of lymphatic fluid

Figure 4

Lymphatic capillaries and vessel wall musculature.

According to Webster’s New World Dictionary (3rd college edition), the word lymph is also influenced etymologically by the Greek nymphē, our English word nymph. In Roman and Greek mythology, nymphs were a group of minor nature goddesses, usually represented as young and beautiful, who inhabited rivers, springs, seas, or lakes: that is, places of clear water. The word limpid, with similar origin, means “perfectly clear; transparent; not cloudy or turbid.”

Owing to its transparent quality, lymph is difficult to see during dissections, so its discovery as part of an integrated system in the body developed slowly over time and arrived late on the medical scene.

Some ancient civilizations—such as China, India, and Egypt—had elementary notions of a “white blood,” possibly referring to the milky, intestinal lymph fluid that follows digestion of a fatty meal. Traditional Chinese medicine speaks of a water element connected with the bladder and kidney meridians; it differentiated between liquids of the body and blood. Ancient India’s Ayurvedic medicine had knowledge of “interstitial liquid,” which represented one of the seven systems of the body. According to the ancient Egyptians, the heart contained liquid; vessels existed that transported organic substances throughout the body.

The Greek physician Hippocrates (c. 460-c. 377 B.C.), often referred to as the Father of Medicine, noted and recognized a milky-white material being drained from the intestines and conjectured that this substance resulted from digested fatty material. This was later shown to be an accurate assessment. He was the first to use the word chyle (a milky fluid formed in the small intestine, composed of lymph and emulsified fats) and also listed a “lymphatic (phlegmatic) temperament” as one of the four main temperaments of the human being. Other ancient physicians did not clearly differentiate blood from lymph, yet they traced the lymph channels in the same geographic pattern as veins (vessels which return blood back to the heart). The actual pathway of these lymph vessels flowing into the bloodstream was not properly mapped until centuries later.

Aristotle (384-322 B.C.) spoke about structures with transparent fluid, while Herophilus (335-280 B.C.) noted the presence of mesenteric lymph nodes and “milky veins” (lacteals). During the course of the centuries following further observations and speculations, there was a surge in the seventeenth century that offered more insights and clarity into the nature of the lymphatic system. Just a few years before William Harvey (1578-1657) presented the physiology of the cardiovascular system in his published works (1628), Gasparo Asselli (1581-1626) noted the “white and milky veins” of a dog in 1622, the first documented discovery of the lymphatic vessels. In 1653 Johann Vesling (1598-1649) followed with the first illustrations of human lymphatics, but it was Olof Rudbeck (1630-1708), a Swedish anatomist and “Renaissance man,” who first recognized the lymphatic system as a complete system and as a part of the circulation. Using the ligature technique, he dissected more than four hundred animals to substantiate his ideas. Other scientists followed and built upon these discoveries and observations with their own theories of the flow of lymph and its function and role in the human body.