Medical brain notes 41

  Body Fluid Compartments   Did you know that an adult body contains approxi-mately 40 liters (84.5 pt) of water? Visualize the vol-ume of 40 1-liter milk containers in the dairy section of your grocery store. About 25 liters (52.8 pt) of this fluid is found inside the cells— intracellular fluid  (see Figure 9.1). The remaining 15 liters (31.7 pt) is  found outside the cells— extracellular fluid.   Of the extracellular fluid, about 12 liters (25.4 pt) are lo-cated between the cells ( interstitial fluid)  and 3 liters (6.3 pt) are located inside blood vessels as  plasma  or  intravascular fluid  (remember that theblood volume of about 5 liters (10.6 pt) is made up of this fluid, together with the blood cells). The fluid in the blood and the interstitial region is continuously being mixed as it diffuses in and out of the blood capillaries. Therefore, the waste products of the cells, which have diffused out into the space between the cells ...

  The Lymphatic System In general, the fluid moving out of the capillaries ex-ceeds that entering it from the interstitial fluid compartment. Also, large protein particles tend to accu-mulate in this compartment. These proteins may be particles that have leaked from the blood into the cap illaries, cell waste products, or remains of dead tissue.   Being large, these proteins cannot be easily removed by the capillaries, however, another mechanism—the lymphatic system —is in place to remove excessivefluid and proteins. FUNCTIONS OF THE LYMPHATIC SYSTEM The function of the lymphatic system is to return ex-cess fluid and protein from the interstitial fluid com-partment back into the blood circulation (see Figure 9.2). If the protein is not returned to the blood, the plasma colloid osmotic pressure will drop, and it will not be possible for fluid to stay inside the circulatory system. Defense is another important function of this sys-tem. Lymphoid tissue is responsible for the prod...

  FUNCTIONS OF THE LYMPHATIC SYSTEM The function of the lymphatic system is to return excess fluid and protein from the interstitial fluid compartment back into the blood circulation (see Figure 9.2). If the protein is not returned to the blood, the plasma colloid osmotic pressure will drop, and it will not be possible for fluid to stay inside the circulatory system. Defense is another important function of this sys-tem. Lymphoid tissue is responsible for the produc-tion, maintenance, and distribution of  lymphocytes,  a class of white blood cells that participates in de-fense. The white blood cells in the lymphatic system remove foreign agents that have entered the intersti-tial region. In the intestine, lymphatics help carry fat and large particles to the liver. In the kidney, adequate lymphatic flow is required for concentrating the urine.

  COMPONENTS OF THE LYMPHATIC SYSTEM The lymphatic system is an anatomic system consist-ing of  lymph vessels, lymph,  specialized cells called lymphocytes (described in the section on Immunity),  lymphoid organs,  and collections of  lymphoid tis-sue  in different parts of the body. Lymph Vessels The lymphatic system is similar to the cardiovascular system because it, too, has vessels, often called  lym-phatics.  Lymphatics are present in almost all the re-gions of the body; however, they are absent from the central nervous system and such regions as the cornea, lens, cartilage, and epithelium that lack a blood supply. The smallest vessels—the  lymphatic capillaries — arise as blind-ended tubes in the interstitial spaces (Figure 9.2). These capillaries have thinner walls, and they are larger than blood capillaries. The lymph cap-illaries are highly permeable and allow large particles to easily enter the vessel. The endothelial cells lin...

  DRAINAGE ROUTE OF LYMPH Knowledge of the direction and route of lymph drainage (Figure 9.3) is important for many reasons. Massage therapists can apply the massage strokes along the direction of lymph drainage and speed lymph movement. Surgeons can plan the extent of surgery or radiation in persons with cancer because cancer cells can be carried by lymph to the nodes draining the area. When treating some types of can-cer, the lymph nodes draining the area are removed or irradiated together with the cancerous tissue. Upper Limbs Lymphatic vessels in the arm (see Figure 9.7) consist of superficial and deep groups, which anastomose. The superficial vessels are present in the subcuta-neous tissue, while the deep vessels drain the muscle,  periosteum, and bone.   Each finger has one to two collecting ducts that join in the dorsum of the hand to form five or six larger trunks, joined with collect-ing ducts from the palm. In the forearm, three groups of drainage vessels are pr...

  Massage and the Lymphatic System Massage has positive effects on lymph drainage. It is believed that the effects of massage are equal to the circulatory effects produced by the contraction of muscles.  Appropriate strokes and drainage tech-niques can help with the movement of lymph and re-duce edema. 1,2  Passive exercise often used in con-junction with massage also encourages lymph drainage. Massage over lymph nodes can speed lymph drainage and hasten the resolution of swelling resulting from adhesions. Massage has been shown to be particularly effective in relieving postsurgical swelling and pain and for enhancing the rate and quality of healing. 3 The removal of edema fluid reduces the incidence of fibrosis in the location. In addition, pain can be re-lieved by removing those chemicals and waste prod-ucts dissolved in the fluid that stimulate pain receptors. MASSAGE AND LYMPHEDEMA Some studies 4,5  have proven the positive effects of  complex physical thera...

  Immunity Rapid progress has been made in the field of immunology. This section gives only a brief overview sufficient to help the massage therapist understand the relevant clinical conditions related to immunity. Immunity  is the ability of the body to resist infec-tion and disease by activation of specific defense mechanisms. The human body has many different defense mechanisms. Some of them are  nonspecific;  they do not differentiate one type of threat from an-other. Others are  specific,  developing defenses specifically against one particular type of threat. Both types of defense need to be functioning to provide ad-equate defense to the body (see Figure 9.9).

  NONSPECIFIC IMMUNITY Nonspecific defenses are present from birth, and they include physical barriers, phagocytic cells, immuno-logic surveillance, liberation of a variety of chemi-cals, inflammation, and fever. Physical Barriers Physical barriers prevent or make it difficult for for-eign organisms to enter the body. For example, the skin is multilayered, and the epithelial cells are inter-locked or held together by tight junctions that make it difficult for organisms to enter the body. The pres-ence of keratin in the epidermis provides resistance against bacterial enzymes, acids, and alkalis. Also, the skin’s accessory structures provide additional protection. The hair protects against mechanical abrasion. Secretions from sebaceous glands contain chemicals (lysozymes) that have antibiotic proper-ties. Even if microorganisms penetrate the epidermis, they are confined to one area by the fascia. Entry of organisms through the mucous membranes of the respiratory, gastrointestinal, ur...